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An open source initiative to share and compare heat pump performance data

_spduchamp
76 replies
5h4m

We moved to heat-pump a few years ago and disconnected from gas. It's been working great. Our biggest expense was insulating our house. It is an old house and the 2nd floor was very drafty. You could feel a breeze coming through cracks in the wall. When we opened the wall there were just a few newspapers in there and no insulation.

We had the 2nd floor siding removed, an extra layer of insulated wall added to the outside and then cladded with siding. It was like putting a big insulated hat on our house. Now the temperature is very consistent and absolute no drafts.

The architect said to me that we'll never fully recoup our costs of putting the hat on the house. To which I replied that we don't always to things for economic reasons, and just do them because they are the right thing to do.

My only regret was going with a Rheem heat-pump water heater in this mix. It does not perform well at all. With hindsight I would have looked for a way to perhaps have water heating integrated with our air heat-pump system. There is a company called Arctic that has those systems.

Also with regard to heat-pump water heater, out big problem is that a hydronic floor heating system (installed when we were on gas) is now constantly drawing off heat from our tank. I'd like to find a small standalone unit to handle floor hydronic heating separate from my main water heating.

mecameron
29 replies
4h37m

The architect said to me that we'll never fully recoup our costs of putting the hat on the house. To which I replied that we don't always to things for economic reasons, and just do them because they are the right thing to do.

I am so frustrated with this analysis and sentiment when it comes to environmental investment. I understand that looking at it with a financial lens can and should be done to inform what we do, and it would be great if a project just paid for itself, but you look at all the other things we spend money on and the same calculus is not used.

People don't buy the cheapest car, house, clothing, or food they could possibly get by with, or analyze the marginal cost of moving up or down the possible price tiers available to them with only the financial payback as a guide. Yet we constantly hear the refrain that you shouldn't spend a given amount of money on solar, house improvements, appliances, etc. that might be better for the environment if the payback isn't somehow positive with a 10-20 year payback period.

I've constantly had to work with contractors to let them know that I still want to pay for the marginal costs associated with investment even knowing that the marginal financial benefit is smaller. For instance, with solar panels in less than ideal locations, tri-pane windows, etc. I have disposable income, and I think the world is trouble for the 8+ billion humans inhabiting it, so I think it's worthwhile that I would spend some of that to make it marginally better even if that means I don't have a positive financial return.

jancsika
10 replies
3h59m

so I think it's worthwhile that I would spend some of that to make it marginally better even if that means I don't have a positive financial return.

Your action is going to make close to 0% difference for the 8+ billion humans inhabiting the planet. So from a practical standpoint, you've failed, but that practical failure makes it clear that the gesture has pure symbolic value for you.

And since that symbolic value stands in stark contrast to incessantly chasing positive financial returns: task failed successfully. Congratulations!

toomuchtodo
6 replies
3h56m

From a practical standpoint, they have valued their energy savings closer to what the true cost of carbon emissions are (remember, most carbon emitters are in no way paying the true cost of their emissions [1]; this externality dumping continues with wild abandon).

You're arguing systems and scale. This person is simply early in the adoption curve. Consider what will happen when this happens more broadly. As the climate situation becomes more dire [2], the price of carbon emissions per ton will rise and the willingness to prioritize energy savings and carbon emission reductions should increase regardless of fiat return. Physical system outcomes are distinct from magic number in database goes up.

But sure, if you're already poor and have nothing [3], this won't matter to you and your life trajectory is already mostly locked in today. As nullstyle mentions, we need to compound in the positive outcome direction, and those decisions are being made today.

[1] https://www.nature.com/articles/s41586-022-05224-9

[2] https://www.npr.org/2024/04/09/1243595924/march-world-hottes...

[3] https://ourworldindata.org/poverty

taeric
2 replies
2h47m

This is a tough one, honestly. For one, being at the early adoption curve also has you on the low side of efficiency. If things aren't being done at scale, they are likely fairly low on that score.

More, though, moving to something that gets you a more climate controlled home in the name of efficiency is odd. You could almost certainly use smaller scale solutions to get more comfortable living that does not involve such a drastic change to the home. Clothing and lifestyle changes are things you can do, for one. For two, though, if the place was so drafty you could feel a breeze, it almost certainly did not have active heating/cooling to the level that they built up to. Such that is seems odd to justify how efficient you could do something that was just not getting done before?

No reason not to do it, of course. But insulation is an expensive thing to add to a house. Not just in raw costs, mind. Most insulation materials are of dubious carbon neutrality. And nothing lasts forever, least of all housing.

toomuchtodo
1 replies
1h53m

Insulation is one of the cheapest improvements than can be done to improve energy efficiency of a structure. Once insulated, those energy efficiency gains persist for the life of the structure. Nothing lasts forever, but homes have a 100+ year service life.

https://www.whitehouse.gov/briefing-room/statements-releases... (control-F insulation)

https://www.energy.gov/energysaver/types-insulation

https://www.energystar.gov/saveathome/seal_insulate/methodol...

taeric
0 replies
1h29m

Homes have a 100+ year service life? Where? I see the median age of housing stock varies heavily in the US. Quickly scanning other markets, I see EU has older housing, in general. Even there, though, they don't talk of 100+ year old houses as being that common.

Scanning websites on this claim, I see that "properly installed, with no damage" some types claim up to 100 years of service for insulation. I strongly suspect that that is a claim that will not hold for the vast majority of homes. More reading also strongly suggests that if your house was built prior to 2005, you probably need to get the insulation redone.

Worse, from my experience, the older the home the less likely you are to have subfloor/walls to actually install insulation. Heaven help you if you do one of those container homes. And if you live in an environment where you have heavy rains or hail, expect damage to creep in rather quickly.

Don't get me wrong, I support the idea that adding insulation is almost certainly a good idea where you can. I just can't bring myself to trust claims of 100 year service life.

wahnfrieden
1 replies
2h30m

There's no consumer-led revolution to come from early adopters accruing over time. It's fringe and luxury activity.

barbazoo
0 replies
57m

As the climate situation becomes more dire [2], the price of carbon emissions per ton will rise

Looking at what's happening here in Canada, where it looks like what has high chances to be the next government is campaigning on getting rid of the carbon tax, these days I'm somewhat pessimistic that carbon pricing will actually be implemented by the top contributors to global emissions. I hope I'm wrong.

zackmorris
0 replies
2h56m

I don't know, I've always dreamed of a world where influential people like yourself saw the value in leading by example.

nullstyle
0 replies
3h51m

“Close to 0% difference”, compounding over time was how we got here. I’m not saying personal responsibility is the only factor, but youre the wrong person in the exchange above, and OP has the proper attitude.

Better is always good

burkaman
0 replies
1h52m

Literally every single accomplishment in human history was built upon millions of small "symbolic" individual actions. Good things don't just magically happen on their own.

ApolloFortyNine
6 replies
2h58m

It's a much more complicated equation, but it's very possible the emissions from simply producing the insulation and having the install done are more than the saved future emissions.

wizzwizz4
1 replies
2h14m

It is possible. You can't measure that in currency, though.

malfist
0 replies
2h1m

If there was a carbon tax you might be able too.

slashdev
0 replies
1h52m

Is not impossible. It’s not likely either.

mrspuratic
0 replies
1h31m

I absolutely agree this kind of nontrivial work can be done in a way that is woefully inefficient/impractical. My EWI, approx 85m2 of graphite polystyrene with an embedded CO2[1] of ~15kg/m2 is equivalent to approximately 1.5 years of CO2 emissions (combined electricity & gas), or ~9 months of CO2 emissions before I replaced windows and old kerosene boiler that came with the house.

Actual installation and other materials excluded (adhesives, mesh, silicone render, 450 hot beverages, getting the neighbour's car repaired after the scaffolders hit it, etc.) excluded.

I don't have a full year of data yet, but all in it's looking like CO2 emissions are going to come in at well under 40%. This is in line with the independent assessment I needed to clear a grant for some of the costs[2]. It seems to me "carbon ROI" is about 1/4 the financial ROI (est 8+ years).

Now if it was PU instead of EPS that would be a different cost (10x the CO2 of polystyrene). Sadly I also ended up with some PU (PIR) in a small area of low-pitched roof void, I don't know if there were better choices there.

There's also a hidden cost in living in a cold, damp building - now there are winter days when I don't even turn the heat on at all.

[1] https://www.greenspec.co.uk/building-design/embodied-carbon-... [2] https://www.seai.ie/publications/Your-Guide-to-Building-Ener...

gregwebs
0 replies
1h57m

Insulation pays back over a long enough time horizon (economically or CO2 wise). Although spray foam at the moment does have a large CO2 impact. If someone is putting in way too much insulation then we could say that the last 30% of insulation wasn't worth it. When people say something won't payback economically on a home, they are usually looking at a time frame of 10 years or less.

In this case the insulation itself will probably payback quickly. The problem is the cost of re-siding the house to get the insulation in- likely similar for CO2 impact.

adrianN
0 replies
1h57m

That’s very unlikely. Insulation lasts decades and is not that difficult to produce.

adrianN
4 replies
1h55m

Imo you recoup the cost via the value of the building. Who wants to buy a drafty house with an oil furnace after 2030 or so?

mortify
3 replies
1h48m

No one will pay more for a house with a higher R-value. If this were a determining factor, it would be part of real estate listings. It's a secondary or even tertiary concern for most people.

toomuchtodo
0 replies
1h33m

If you're buying a house without asking for the trailing twelve month energy bills, you are an unsophisticated real estate market participant and will pay for the ignorance over time.

adrianN
0 replies
1h37m

Where I live you even get better conditions on your loan if you buy a house with better insulation, it’s that important.

flightster
2 replies
2h37m

People don't buy the cheapest car, house, clothing, or food they could possibly get by with... Yet we constantly hear the refrain that you shouldn't spend a given amount of money on solar, house improvements, appliances, etc. that might be better for the environment if the payback isn't somehow positive with a 10-20 year payback period.

I think the key thing here is that energy is 100% fungible unlike your examples. A kWH is a kWH.

dap
0 replies
1h53m

But you’re not buying kWh in this example. You’re buying home energy systems. They have many tradeoffs, pro and con. Besides that, for many people, a kWh produced by a renewable energy source or that’s available to them when the grid is down is worth more than one produced by a coal plant that might be unavailable during an outage.

Scoundreller
0 replies
2h15m

Sorta, around here, a bucket of kWh at 2PM sells for more than the same sized bucket at 2AM.

dfxm12
1 replies
1h34m

It shouldn't be a surprise. Our economic system and even economics-related media puts individual short term gains above all else. Everything is viewed through the lens of "what makes me the most money today?" Long term positions are not valued. Positions that might benefit others are not even considered.

rahimnathwani
0 replies
55m

  Long term positions are not valued.
Stock market?

  Positions that might benefit others are not even considered.
ESG?

zardo
0 replies
42m

The architect said to me that we'll never fully recoup our costs of putting the hat on the house. To which I replied that we don't always to things for economic reasons, and just do them because they are the right thing to do.

I agree, what kind of hat is your house wearing?

belter
10 replies
4h58m

How noisy is it? I heard of people installing them, and getting complaints from the neighbors.

WirelessGigabit
7 replies
4h51m

They're as noisy as an AC. So here in Arizona no one cares. But in Belgium this was an issue as they run more in winter and in winter sound travels further.

triceratops
2 replies
3h40m

In the winter everyone has their triple-paned windows closed. Is noise that much of a problem?

wussboy
1 replies
2h23m

Is triple pane common in Belgium? It’s not in the UK (as far as I recollect) and they’re colder than Belgium

WirelessGigabit
0 replies
1h56m

I built a house in 2014 there. Triple pane. Pointless. You never recoup the cost.

belter
2 replies
4h48m

Uhmm...I see a problem for countries where you have wall to wall connected urban environments...If all 60 connected houses on a street, install external heat pumps, it will add up.

toothrot
1 replies
4h20m

Turns out cities are loud! In NYC, at least, heat pumps are far more quiet than the endless window unit A/C's, or larger traditional A/C's, in my experience.

Outdoor noise is less of an issue in the winter in big cities because windows are closed.

wussboy
0 replies
2h22m

Most of the noise in cities is cars. One idiot on a Harley drowns out a warehouse of heat pumps

cduzz
0 replies
4h28m

Just installed heat pump systems (daikin) this december.

The exterior unit is basically silent even when there was a cold snap (below freezing but not northern alaska cold).

I suspect an interior air source heat pump hot water heater, being smaller, will be noisier, and likely less efficient.

I'd love to switch my 240v/30a water heater to use a 120v/20a service, but will wait a bit longer for the technology to mature. Ideally it'd have the heat collection part outside.

switch007
0 replies
2h22m

Also, when talking about noise it's important to talk about frequency. If they produce low frequency noise, that can be far more irritating. Shutting the windows won't help much

jillesvangurp
0 replies
4h8m

Depends on the installer. A lot of noise results from units that are not properly mounted or mounted at a slight engine. The fan then starts getting more noisy and wears out earlier. There are other problems to not installing units properly.

Aurornis
9 replies
4h52m

The architect said to me that we'll never fully recoup our costs of putting the hat on the house.

Your architect is almost certainly right. I would bet that most of your improvements came from fixing the drafts, with the insulation providing a marginal improvement on top of that.

I’ve also dealt with insulating old homes, but I did draft fixes, wall insulation, and attic/roof insulation at different stages. The draft fixes provided the most improvement, followed by attic/roof insulation. Insulating walls had much less effect than I anticipated.

In friends’ houses I’ve used my thermal camera (which I didn’t have back then) and it’s easy to see where the heat or cold is coming in during weather extremes. These days I’d recommend anyone start with the thermal camera view before deciding where to spend money on insulation.

tstrimple
3 replies
3h47m

Insulating walls had much less effect than I anticipated.

I wonder if that's due to air already being a decent insulator and walls have sizeable air voids. As long as you cut out the drafts, the air in the walls should remain a decent insulator. It's also my understanding that the draft treatments are at least as important as the insulation work which is done when retro-fitting insulation. One reason attic insulation would make a much larger difference is most homes with attics use vented soffits designed to encourage airflow. They are built to be drafty and you can't seal up those drafts without redesigning things.

MarkMarine
2 replies
3h21m

Depends what your walls look like inside. If it’s balloon framed with no blocking, you’ll have a good convection current inside the wall.

The moisture concerns when trying to add insulation to an old uninsulated house are real, in service of saving a few thousand dollars of heating costs you could literally destroy your house and your health with mold.

zer00eyz
1 replies
1h51m

Someone is going to come by and look at your comment and raise an eyebrow.

The building trade and construction is filled with nerds, amazing products, cheats and snake oil... so just like tech but less VC'c.

https://en.wikipedia.org/wiki/Building_science building nerds are on point and doing all kinds of cool stuff. If you want the modern version of bob villa this old house is probably this: https://www.youtube.com/@buildshow . It will give you some clues as to what is going on in modern construction.

MarkMarine
0 replies
50m

Oh I’ve seen buildshow. I have also seen him talking about mistakes he made in the older designs he had. I would be real cautious about letting a builder at a lower tier than him beta test their ideas on moisture control inside my walls when I’m the test dummy inside.

mpaepper
2 replies
4h34m

What kind of thermal camera do you recommend and what price range?

andrewblossom
1 replies
4h7m

I bought a Topdon TC001 a year ago that in my experience is significantly more responsive and higher resolution than similarly priced FLIR or other name brand options at that price point. It appears there are even more low cost options now.

MobiusHorizons
0 replies
1h21m

I find it rather interesting that companies like FLIR are limited by regulation (I believe US export bans) from selling IR cameras with greater than 9fps. there is also a resolution cap but I forget what it is off-hand. Strangely enough this doesn't stop US citizens from purchasing higher performing cameras from non-US companies. I think technology has come down significantly in price over the last few years and you can now get smartphone attached versions like infiray for a few hundred bucks.

pjc50
0 replies
4h41m

Thermal cameras have got really cheap: I found one on Aliexpress for less than £150, that plugs into a smartphone.

dylan604
0 replies
3h21m

Even if you don't use a thermal camera, just the thermal thermometers work as well. Sure, you have to take more readings, but the result is the same. A lot of people probably have one of these now after Covid, and can at least test things out before going to the step of a full thermal camera.

I have a bedroom that has a shared wall with a water heater which causes this room to be hotter than the rest of the house. Using the thermometer showed the temps after I added a barrier to the inside of the utility closest dropped significantly.

Merad
6 replies
2h13m

I think the biggest hurdle to heat pump adoption (at least in North America) is likely to be that it provides an experience that simply isn't as good as a gas furnace. On a chilly morning the air coming out of the vents just isn't that warm and it may take hours to bring the house up to temp, whereas gas puts out pleasantly warm air immediately and can quickly warm the house even on the coldest days. When it's truly cold (like < 20F) the heat pump will run continuously and struggle to maintain temp. Don't misunderstand, the heat pump is certainly _good enough_, but people typically don't pick the "good enough" experience over the "better" experience when the better option is available and they can afford it.

For reference I've lived in NC and TN near the mountains where heat pumps are pretty standard. I imagine we don't get the ultra high efficiency cold weather heat pump units that would be used up north, but they also get much colder temps than us. Several of the houses I've lived in have been recent construction (2008 and 2018), so well insulated and reasonably new & efficient heat pumps. For the last 2 years I've been in a house with gas, and it's just so damned pleasant... I know on paper that heat pump is better, but I really don't want to give up that furnace.

antisthenes
1 replies
2h3m

I think the biggest hurdle to heat pump adoption (at least in North America)

When it's truly cold (like < 20F) the heat pump will run continuously and struggle to maintain temp.

Luckily, pretty much the entire Western and Eastern Coastal areas, it doesn't actually get that cold on a regular basis, except a few days in the winter. The US is actually in an incredibly advantageous geographical position for at least 60% of households to be on heatpumps, as opposed to, say, Finland/Canada/Russia etc.

napoleongl
0 replies
50m

Meanwhile it was estimated that half of Swedish houses were equipped with heat pumps in 2016. That number has certainly not gone down since given the steep rise in electricity costs we’ve had since. Many houses have been converted from horribly inefficient direct electric heating to heat pumps.

Ataraxic
1 replies
1h47m

It doesn't have to be all heat pump. You can have a backup gas heat for the coldest days, or even resistive heat. I'd bet there are heat pumps that integrate those technologies to ensure a nice experience.

mholm
0 replies
1h39m

When I got a quote to upgrade my resistive heater to a heat pump, the added cost to get a backup resistive heater (with the same capacity as my existing one) was only $500. Seems like as long as you're wired for it, it's very cheap.

SECProto
0 replies
1h37m

A relative recently upgraded their 120yr old house with heat pumps, and the warmth is so much better than where I currently live (a 40 year old home with a new gas furnace). In my experience you can't generalize about heat source.

Mvandenbergh
0 replies
1h51m

Part of the problem is that heat pumps aren't really well suited to a use case where you frequently have to bring a house up to temp in the way you're describing. If you have a big overnight set-back and then the heating comes on in the morning, that will require much more heat output than constantly putting out enough heat to maintain temperature.

In a well insulated property, the greater efficiency from operating at low output temperatures outweighs the additional heat loss from no / a low overnight set-back. In a poorly insulated property, the optimum set-back is higher and the efficiency at that optimum point is also much lower because the heat pump has to operate at higher temperature in order to ramp up the temperature.

I don't know if they are available in North America, but in the UK we have hybrid systems available that use heat pumps for 80% of the annual heat load and gas for peaking / ramping. OpenTherm gas boilers can be retrofitted to be controlled in this way so you only add the heat pump. An air source heat pump driving a hydronic / radiator system in this climate can serve 80% of the annual load with a unit sized at 55% of peak heat load. Different climates will have slightly different numbers but it shows the power of a hybrid system as you save a lot on HP capex and also maintain redundancy.

The advantage of this system is that the failure-mode of an incorrectly sized system is an efficiency penalty rather than not being warm enough, the same as an incorrectly commissioned or sized gas system. (Most gas systems are not optimally sized or configured and are delivering 5% to 10% less efficiency than they could).

I don't know if these systems are available in ducted air configuration for the US market though.

loceng
3 replies
4h9m

Have you ever monitored the air quality levels in various rooms?

Curious if getting rid of those drafts may be unknowingly affecting your health in other areas.

doctorhandshake
2 replies
3h56m

My understanding is that any house that isn’t built ‘tight’ by today’s standards will have a fast enough ACH that you don’t need to worry about ventilation as you would with a tight house. And only a ‘deep energy retrofit’ of an older house would result in tightness like that, so ERV and MUA etc are not necessary. Local code, build detail, and age of house are factors, YMMV, but this isn’t a problem you’d cause by accident with anything but a very invasive retrofit.

amluto
1 replies
3h27m

Mechanical ventilation is not necessary in a drafty house, but it’s still very nice to have. Bonus points for a well-filtered system. (None of the major brands will sell you a system that is well filtered out of the box. But it’s straightforward, if rather space consuming, to put a monstrous filter with effectively zero pressure loss in series with the system.)

Bonus points for taking advantage of a balanced ventilation system’s ability to continuously extract air from stinky areas, e.g. bathrooms.

Even more bonus points for avoiding negative pressure due to conventional bathroom exhaust, which can defeat stack effect-based exhaust from non-power-vented combustion appliances, which are, for some reason, still legal.

(Seriously, WTF. There’s a straightforward design that could safely created a forced draft even with legacy leaky ductwork: put the fan on the exterior vent terminal, so the duct is under negative pressure. The wiring could be fished through the existing duct using class 2 / SELV wiring with high-temperature insulation. A pressure or airflow-sensing interlock in the appliance could prevent gas flow if the fan stops working. Sadly, I’ve never heard of a system remotely resembling this. The choices appear to be stack effect (category I or II) but basically crossing fingers and hoping the pressure works out) or positive-pressure sealed but not tested “category III” or “category IV” pipes and crossing fingers and hoping that the pipes are actually airtight.)

doctorhandshake
0 replies
1h19m

Yeah I believe GOLogic’s designs have the ERV exhaust in the kitchen, bathroom, and laundry, and the fresh air return in the living spaces and bedrooms. I definitely like the idea of that, especially with filtration.

mataug
2 replies
4h16m

My only regret was going with a Rheem heat-pump water heater in this mix. It does not perform well at all.

Heat-pump water heater's performance depends a lot on where its installed and the airflow+heat available. If the water heater is undersized or if there isn't enough heat in the air, it would perform worse than a standard gas/electric water heater.

Mine is installed in a closet under the stairs, which is not ideal, but as long as I keep the water heater in eco mode, and keep closet door slightly open, it works good enough for our usecase. Our annual water heating costs went down from ~$500 to ~$100 after switching to the heat pump water heater.

usrusr
1 replies
3h49m

As in the cold end of the heat pump is inside the heated area of the house? That feels very weird. On the other hand with heat pumps, stacking multiple stages strategy isn't necessarily a bad thing! All inefficiencies are not really losses but merely resistive heating contributions (unless their heat escapes to the final cold sink aka outside) and in the end the real question is which configuration is good in terms of capex and maintenance.

In an environment where getting rid of humidity is a concern (mold!), a "cold end inside" heat pump for water might even double as a dehumidifier, with water condensing on the cold end sent to the sewers, contributing a little energy in the process.

sf_rob
0 replies
1h39m

That's not uncommon and is even beneficial in warmer climates. It will be parasitic in winter (even if externally vented) and symbiotic in summer.

rayiner
1 replies
3h31m

There’s a couple of big problems with the heat-pump industry in the U.S. First, people get their advice about HVAC from the tradespeople, who are way behind the curve on heat-pump technology. Second, and relatedly, the trusted American HVAC brands are far behind China and Japan and Europe on heat pump technology, especially cold-weather capable inverter units.

I had our heat pumps replaced here in Maryland in 2019-2020 with mid-range Amana (rebranded Daikin) units. Decent efficiency, but output drops to half at 10F. The guys who recommended the system, a trusted local business, didn’t even tell me about that. Even in Maryland that means waking up to a cold house several weeks out of the year. That means we needed to keep our oil-based backup heat in place, which is a huge expense to maintain. (Also, our HVAC guys didn’t know that the communicating Daikin units can’t control external auxiliary heat, so they just left things with no backup heat whatsoever.)

After educating myself about this, I wish we had installed one of those Chinese inverter based units, like the Gree Flexx. But if I asked my HVAC guy about that they’d stare back blankly. And the folks who do know what they’re doing can charge whatever they want. The price of getting a mini-split installed here is several times the price of the unit. The $16,000 we spent just a few years ago for two condensers and air handlers looks downright cheap compared to what it would cost today.

Regarding your floor, we have a similar situation with radiant heat in our basement slab. I’ve been looking to ditch our oil boiler, but there’s basically no heat pump options that are widely available. (I don’t want to install some imported Chinese air to water heat pump that the local guys can’t fix.) With heating oil prices being over $4, though, I’m looking at just biting the bullet and installing an electric boiler, which is at least something I could probably fix myself.

mrb
0 replies
2h4m

I feel you. The lack of knowledge among American tradespeople is infuriating. As soon as you deviate slightly from the brands of furnaces they have been installing for decades, they don't know anything.

jbjbjbjb
1 replies
4h46m

On the payback period, that’s probably just outlay divided by energy savings. I’m sure you’d get more enjoyment from a more comfortable house and the next owner will appreciate the modernisation too so those need to be factored into the investment appraisal.

I doubt the architect puts such a miserly lens on the other projects they’re involved in.

jillesvangurp
0 replies
4h11m

This is actually becoming an important point. In parts of the world where energy ratings matter, they have an impact on house value as well. They unlock incentives, etc. A house that is up to modern standards is simply worth more because any new owner does not have to do expensive renovations to modernize. In the Netherlands house flipping is pretty common. Buy something old, modernize it, live in it a few years and make a profit. The lower energy cost is both a nice bonus and a key selling point.

ip26
1 replies
3h35m

Drain water heat recovery seems like the best efficiency boost for water heating. Completely passive, 60% extra heat energy. At least for cold climates. Heat pump water heater might be phenomenal in a Phoenix garage.

_JamesA_
0 replies
3h29m

A heat pump water heater seems phenomenal to me in an Austin attic. And I use the cold air generated to cool a wiring/server closet. Win/win.

mechagodzilla
0 replies
2h27m

Wait - you have a HPWH connected to a hydronic floor system? That's an extremely inappropriate setup - the heatpump on a rheem is probably like ~4000 BTU/hr, and it's pulling the heat from the conditioned space, then you're drawing it off and pumping it back into the space via the floor. If you don't have an air-to-water heatpump and don't want fossil fuels, just use an electric boiler.

kingnothing
0 replies
4h54m

What problems are you seeing with your water heater? I’ve had one for about a year and have been pretty happy with it after learning I needed to schedule high demand times of day. It is a bit louder than I’d like but it’s not horrible.

danans
0 replies
3h24m

The architect said to me that we'll never fully recoup our costs of putting the hat on the house.

That's only true if value your added comfort at a very low price. The problem is that it is hard to put a value on the comfort of a house, either while living in it, or while selling it. Hotels, however, do it all the time, but it's easier since they are in the business of selling comfort at various levels.

GenerWork
0 replies
2h31m

My only regret was going with a Rheem heat-pump water heater in this mix. It does not perform well at all.

Sorry to hear that. My Rheem heat-pump water heater works fantastically, although I do live in a hot climate so that could be why.

1123581321
0 replies
2h53m

That's a shame about the Rheem. Ours has been overperforming my financial model in the standard eco mode. We do have an advantage in that it sits out in the open in the unfinished part of the basement, which runs slightly warm in the winter due to a ductwork problem. No venting was necessary.

It's definitely challenging to find trades who have both the knowledge and interest to innovate relative to standard HVAC installations in the area.

Faaak
51 replies
7h32m

Heat pumps _are_ amazing! The power of physics at play: spend 1 unit of energy to gain 4.

Some naysayers will say that it doesn't work the 3 days of the year where it's -15°C outside, without talking about the other 100+ days where it's not that cold and where the heat pump is amazing.

Disclaimer: I self installed one for my house (13kWth) and I'm very glad I did

verelo
22 replies
6h48m

So, i have a house in Haliburton Ontario. Historically we drop a cool $3k a year on propane.

Last year we installed a Mitsubishi hyper heat ductless system.

We used zero gas this year. Read it again, zero.

It’s lakefront, very remote, and the largest electricity bill i got was around $450 for a month and then they dropped back to something more like $250. The savings are huge, I’m no longer stressed about running out of gas…and the heat pump performed well beyond its advertised specifications. We had a few -25C days and it was humming hard, but the house stayed a comfortable 20C inside. The house is around 3000sqft and we didn’t even get the largest unit, i can’t stress enough that they actually operate better than advertised.

We would run a fire from time to time but we did that with propane too, it’s mostly ornamental.

https://photos.app.goo.gl/FCwLJQAtoG67g9y86

https://photos.app.goo.gl/TwiMaSAj9hGxYqby6

https://photos.app.goo.gl/gYVYvVEB3whLCv1dA

https://photos.app.goo.gl/49RcBdBuUZ2jVN3J7

jefftk
12 replies
6h8m

It's worth running the numbers based on your particular utility costs, though. In our case, with somewhat expensive gas and very expensive electricity, the heat pump would have cost quite a bit more to run: https://www.jefftk.com/p/running-the-numbers-on-a-heat-pump

stephen_g
4 replies
5h35m

With an air-to-water system like a Vaillant aroTHERM plus you could possibly achieve your break-even COP of 4.5 (the 12kW unit costs about US$7,200 in Europe, although from what I hear about the US heat pump market you'd probably pay like $20K for the unit alone for some reason).

(Also, how do you guys function with those strange units? Therms, BTU/hr, etc. - all so confusing. Surely electrification and the shift to heat pumps could be a convenient excuse to start using watts (kW in this magnitude) for heat and joules (usually MJ) for gas!)

jefftk
3 replies
5h26m

I do think an air-to-water could make sense for us, though it wouldn't be able to handle the coldest days because our radiators aren't sized to keep the house warm at the lower water temperatures it puts out. The main problem is figuring out who can install one, since it's a pretty unusual product here.

(You get used to whatever units you're using, and the US units make some calculations easier and others harder. If I could switch it all over to the SI system without massive transition costs I would, though!)

sokoloff
2 replies
5h0m

You might be surprised at how well cast iron rads can provide comfort at low outside air temps and low flow temps. (I'm in neighboring Cambridge in an old, poorly/non-insulated house.)

https://news.ycombinator.com/item?id=39144329 has a bit of details on the experiment I ran back in 2022 to prove 135°F flow would work for us. (If you have a condensing boiler, you can run this experiment safely; if you have a non-condensing boiler, you can run it, but not for very long as you'll be damaging the flue and boiler with condensation at these lower temps.)

My outdoor reset curve (sadly, on a gas combi boiler because of the "pretty unusual product" factors) is now set to 105°F at 55°F OAT and 154°F at 0°F OAT (which is lower than the design temperature here, but it gave me more resolution to tweak the line to fit the loss just right; it's spot-on on the lower end, with the system running 22-24 hours per day when it's cold out and stays that way up until around freezing, where the utilization falls off).

Matching the gain to the loss quite closely has resulted in a house that's the most comfortable since we moved in in 2007 and gas bills with the combi went down about 46% (versus a 1990s oil-to-gas conversion of a 1950s boiler, so not a realistic comparison for anything that wasn't built by General Motors [not a typo]).

jefftk
1 replies
4h48m

We have one loop with cast iron radiators, but the other two loops are modern baseboard. When we installed a condensing boiler in 2015 I needed to adjust the outdoor reset curve up so the loop that serves the first floor wouldn't leave it under temp on cold days.

Even our cast iron radiators are smaller than you might expect for the age of the house, because they were designed for water above its normal boiling point (using mercury pressure: https://www.jefftk.com/p/mercury-spill).

sokoloff
0 replies
4h22m

I also have one loop of modern baseboard. Fortunately, it's in the attic conversion where they did insulate the rafters while doing the conversion, so it works even at that lower temp. I did do something slightly unconventional in plumbing that zone in a primary/secondary and it gets the water from the boiler "first" and returns it to the primary loop ahead of the main zone which is all cast iron rads. That means the baseboard gets the hottest water possible and the full potential flow from the boiler if it "needs" it. In practice, that zone tends to only run 4-5 hours per day while the main zone is running 22-24 hours, so either what I did works really well and/or I didn't need to do it in the first place.

But, you've already discovered your reset curve with modern equipment, so you know the right answer for your place.

Thanks for the story on mercury pressurization! Fascinating. I learned a lot about our old house (originally gravity circulated as well, but near as I can tell, pressurized only to the typical 12-15 psi and with an in-ceiling green steel expansion tank: https://structuretech.com/wp-content/uploads/2020/03/Old-sch... )

(And of course, sorry to hear about your contamination inconvenience and expense!)

davidw
3 replies
3h30m

We got a heat pump installed alongside the gas system, since it's still working.

I would love it if there were a service or some code to look at 1) gas prices 2) electricity prices 3) how efficient the two systems are and switch back and forth depending. Like... if it's -10C out, run the gas. As it gets closer to 0C, switch over at some point.

If gas is flat out always cheaper, you could still put a cutoff point where you're willing to spend a bit more because it's better for the environment.

verelo
2 replies
2h39m

Depends where you are. Gas is certainly not cheaper for us. I did the math based on cost per KWH of fuel consumed v's the efficiency of the unit producing it. Natural gas would be slightly more expensive (marginal though...2% or so) but propane is around 3x more expensive, and with many people on oil the math is even worse.

In many regions electricity isn't as cheap as ours though, so that changes the game.

davidw
1 replies
28m

Right - it feels like a pretty dynamic calculation and it'd be cool if there were a service to do it for you.

verelo
0 replies
7m

The number of times I've almost started making that service...maybe when I get a free moment, I really want it to exist too.

verelo
2 replies
2h45m

100% agree. Our electricity costs are fairly low, and its a very low carbon source (mostly hydro electric + nuclear), so for us it makes a huge amount of sense. If you're in Alberta, where most of the electricity comes from coal...theres no logic in switching to electricity.

I'd argue that's politically motivated and very deliberate however...

stormbrew
1 replies
29m

Almost all coal plants in Alberta have been shut down and it's a small minority of net generation now. Natural gas has taken up most of the slack, but there's actually quite a lot of solar and wind generation in Alberta considering the politics (though that's likely to slow down now).

http://ets.aeso.ca/ets_web/ip/Market/Reports/CSDReportServle...

verelo
0 replies
8m

Ah i didn't realize the coal plants were retired! That's good to see. I was looking at the carbon impact per kwh in Alberta earlier in the year for a project I was working on, and was surprised how high it was. I guess other areas of the country just have a lot of other sources diluting the impact.

Siecje
3 replies
6h16m

That's a lot of lines going to the outdoor unit.

Is there two per indoor head?

matthiaswh
2 replies
6h5m

It looks like that unit may have 3 indoor heads. Two lines per head. Power to each head. Power to the outdoor unit.

bluGill
1 replies
5h35m

Looks like it. I'd suggest anyone looking at a system like that install at least 2 separate outdoor units. That way if one breaks the other can still work - and most of the year it will be powerful enough to handle the whole house (some rooms will be a little uncomfortable but bearable)

verelo
0 replies
2h45m

This is correct, 3 heads. One on each level of the house.

itsoktocry
2 replies
5h32m

Historically we drop a cool $3k a year on propane.

Similar to our situation, also in Canada; we cut our fuel bill by 3/4 after getting a heat pump. I still run the furnace on the coldest days, because it's hard to beat. But 9 days out of 10 the heat pump is all we need. The fact that it doubles as an AC unit (and is even more efficient) is gravy.

I also bought a heat pump hot water tank, and so far so good.

verelo
0 replies
2h43m

Yeah! The AC bonus is amazing. The summer gets so sticky, not anymore. We got it in around July I think, made for an amazingly comfortable August.

sentrysapper
0 replies
4h24m

Can I ask what model did you get and what part of Canada are you in?

More to the point, I'm looking for a recommendation for a smaller unit to heat 750 sq ft. in Quebec.

bregma
1 replies
4h38m

I live a few 100 km east of there and just had a heat pump installed last fall. I still have to spend $800 a year on wood but now my home is 20 C all day every day and I no longer have to break the ice on the dog's water bowl in the mornings. I still fire up the stoves to keep hydro costs down and so far the hydro bills haven't been particularly different from previous years when I had to use supplementary electric resistive heat. Then again, it's been a particularly mild winter with zero days below -30.

I had a Moovair with three heads installed.

verelo
0 replies
2h41m

This winter was really mild. I was curious if we'd spend more or less, and honestly i wasn't super concerned. My napkin math suggested it would be comparable, but come with the benefit of reducing the risk we'd run out of gas. The propane truck cant make it up our road from late November early April, and last year we got down to around 20% remaining (which is around the point where the tank stops working due to there not being enough pressure).

Huge bonus that its been cheaper, and substantially...but I just love relaxing about the reduced risk of the house running out of fuel.

gjm11
17 replies
7h16m

In fairness, the days when it's -15°C outside are exactly the days when you really want your heating to work well...

derkoe
14 replies
6h59m

Most heat pumps fall back to electric heating when it's too cold. So, on these few days you will need the same amount of electricity a typical electric heating will need.

tomohawk
9 replies
6h26m

which spikes the electricity demand from the grid and puts it under the most strain when its most critical for the grid to stay up, which means the grid has to be overdesigned, which means that the air based heat pumps are a poor choice for a reliable grid.

beejiu
3 replies
4h56m

The UK is rolling out smart meters to every property. In the past 2 winters (following on the Russian gas crisis), they have run programs that pay £3 per kWh reduced demand. This is a nice way to balance the grid during extreme demand.

michaelt
2 replies
4h12m

> programs that pay £3 per kWh reduced demand.

That much? How do I get in on that?

My energy supplier's demand reduction scheme only pays £10/month total.

beejiu
0 replies
1h40m

It's called the National Grid ESO scheme and you sign up through your supplier when it's open. However, some suppliers take a cut of the ESO payment. Alternatively, you can sign up to Uswitch Utrack (https://www.uswitch.com/mobile-app/), which passes 100% onto the customer. (Disclaimer: I used to work at Uswitch.)

yurishimo
1 replies
6h21m

It depends on where you are. In many places worldwide, extreme cold is also generally quite clear from clouds unless you're literally in a storm, in which case, the high winds are just as likely to cause problems. Rooftop solar should be more than enough to offset your own usage.

bluGill
0 replies
5h13m

In nearly all places extreme code means dark! Sure there are less clouds, but the latitude is high and so there are not only few hours of daylight, the earth's angle is also working against solar.

sanderjd
0 replies
6h13m

I don't think this conclusion follows. It is true that variability is a challenge for grids, but it is not clear that it is better to trade more total energy usage (per useful unit of work) for less variability. Variability is certainly a challenge, but not an insurmountable one, and also one that must be faced regardless nearly everywhere, as solar power has become too cost-effective to be ignored.

rssoconnor
0 replies
6h15m

The demand comes at the coldest part of the day, which is typically overnight, which is far off peek demand times.

jtbayly
0 replies
5h57m

Isn’t electricity demand always going to be highest on the coldest days?

thehappypm
3 replies
6h12m

This is untrue. Mitsubishi hyper heat units do not have this feature, and they’re the gold standard. I wish they did, though

sokoloff
2 replies
5h27m

Hyper Heat is a tech that is on multiple different models of Mitsubishi. All of the SVZ (ducted air handlers attachable to Hyper Heat or H2i mini-splits) do support (optional) electric resistance heater kits.

thehappypm
1 replies
4h16m

That’s correct, air handlers for ducted systems can absolutely have heat strips. That’s actually pretty standard. I have never seen one for a mini split though — can you share a link?

sokoloff
0 replies
3h58m

https://ces.mitsubishielectric.com/wp-content/themes/melco/a... documents the SVZ indoor unit's ability to have electric resistance heat and be connected to Hyper Heat SUZ outdoor units.

Whether you call that mini-split or not is up to you, but it's definitely a heat pump system that is Hyper Heat and supplemental electric heat capable, and getting down to one-ton units seems "mini" to me.

Mini-split means "smaller than conventional system ["mini"], condensor and evaporator are connected by long refrigerant lines ["split"]". It doesn't necessarily mean "wall/floor/ceiling indoor unit that has no ducts", though a "ductless mini-split" is the most common configuration of mini-split (because of the cheapness and ease of installation). https://zeroenergyproject.com/2022/03/09/what-is-a-mini-spli...

magicalhippo
0 replies
6h39m

We have a air-to-air heat pump (minisplit). We also have heat foil in the floors. We've had weeks around -20C and below most winters.

I do hear the minisplit working hard those weeks, but we just needed a bit of extra help from the floor heating to have a comfortable 20C indoor.

Mountain_Skies
0 replies
5h15m

Depends on how many of those days there are. If it's only half a dozen or so, I can deal with putting on an extra layer of clothing in the house for a handful of days per year. As long as it's warm enough inside to prevent damage like pipes freezing, a small amount of personal discomfort for a few days is acceptable.

wernerb
3 replies
7h10m

This needs far more attention. Combi boiler installers tend to massively oversize the CV. But with heat-pumps you need to be far more accurate. And it does not make sense to design for a temperature that occurs only a couple of days in the year. You can just have the backup heater kick in which is far more efficient for a couple of days than having a heavier heatpump for the rest of the year that can not modulate back as much as a smaller heatpump.

rssoconnor
1 replies
6h17m

than having a heavier heatpump for the rest of the year that can not modulate back as much as a smaller heatpump.

Aren't basically all modern heatpump variable speed, and thus can modulate back?

That said, I totally agree with your overall point about right-sizing your heat pump, but it is more about saving money on the unit rather than worrying about cycle times.

bluGill
0 replies
5h32m

Modern heatpumps can modulate, though it isn't 100%. I recommend people consider two smaller heat pumps in many cases - it costs more upfront but can modulate down more and if one system breaks the other can handle everything most days of the year (some rooms will be a bit uncomfortable)

thechao
2 replies
5h28m

Disclaimer: I self installed one for my house (13kWth) and I'm very glad I did

My HVAC guy keeps telling me to install a couple of heat pumps (he doesn't like driving out to me), solar panels, and an in-house battery; what sort of complexity was this job? Are there online sources you used?

sumtechguy
0 replies
4h9m

With this sort of work let the HVAC guys do the research for you. Call 3 of them get quotes. Then research what they are offering. Pick the one you like. Last time I did this around 2008 it was about 5k-15k I was quoted. I asked all 3 for a small, medium and large systems. For me it was mostly an in place replacement. The ducts were already there. The refrigerant lines were all ready in place. The biggest cost was the unit themselves and some change out of the controllers. The labor was about 1 days worth of work for 4 guys.

You can also gain quite a bit by just fixing drafts and putting in proper insulation. Which can be much cheaper to do. I also had the guys go thru and fix an leaks in the duct system. That way the air was coming out where it should. It is amazing how badly that is installed many times. I also had them put in an attic fan which vented the attic when it got to about 110F. Insulation would have helped more there and I screwed up and put it off. If your house is older than 2000. I say go thru and review the existing insulation and look for drafts first.

It trimmed my bill from about 350 a month to 200. My new house has excellent insulation the house is slightly bigger and the power bill is in the 80-150 range (less because I got solar, but I figured out the actual cost anyway). It has one unit and an air valve to switch between the floors. So the total cost is lower but the one unit will run longer. That savings I am getting is mostly because of better insulation.

matthiaswh
0 replies
4h38m

Installing heat pumps doesn't require a ton of domain knowledge (assuming you're already a handy person), but it's a lot of work. It took 3 guys who do it for a living 160+ man hours to install our mini-splits. They had to drill through walls, attach channels to the siding, crawl into a tight crawlspace, do some plumbing when they hit a water pipe with their drill, wire up electrical, and add breakers to the panel.

The only thing that might catch you up is designing the system and ensuring you right size it for your heat load requirements. I'm sure you could research this pretty well, but your HVAC guy might also be happy to consult on that portion.

switch007
0 replies
2h36m

Just to be clear, it works perfectly at -14c and above? Or is there some disappointing performance in an intermediate range?

I'm in Northern England and it's not uncommon for weeks of -5c to 5c in winter, some snowy days, plus serious damp making it feel even colder. So I'm curious if a similar system would be similarly amazing here.

I've read many people say they work perfectly because it won't hit -20c (a nice Strawman...)

dghughes
0 replies
3h16m

Some naysayers will say that it doesn't work the 3 days of the year where it's -15°C outside,

That used to be true but modern air-source heat pumps are better. But even so the efficiency drops it's just physics. Even if a heat pump can grab heat at -15C it will need to run longer when it's very cold, reducing lifespan of the unit. At some point it will just switch over to pure electric so your power to heat 1:4 is now 1:1.

Ground source heat pumps are far better and even more efficient that air source but quite expensive to install.

corbet
0 replies
4h50m

-18°F here (-28°C) here this winter. The heat pump (Mitsubishi) definitely worked hard and burned through our net-metering credit, but it did what we needed it to do. -15°C is just not even remotely a problem.

RedShift1
25 replies
8h35m

A world map and efficiency/consumption would be nice, so we can see where in the world heat pumps are most effective.

akira2501
24 replies
8h18m

so we can see where in the world heat pumps are most effective.

They're not efficient when the temperature drops below a certain point. This is predictable and based on system design criteria. It doesn't mean it's not effective, it's just that it wouldn't be a reliable source of heating year round. It may still make a worthwhile addition to another system, or combined with several other upgrades, may become an acceptable single solution.

brnt
12 replies
8h12m

Reliable and efficient are different things.

A solution that is inefficient two week a year but efficient the rest can still be cheaper than some hybrid setup.

If it is expected it simply won't work a few weeks a year, sure, that's clearly not effective.

akira2501
11 replies
8h10m

You've summed my points exactly while missing the major one. You don't need monitoring to determine any of this. You can just look at the construction of the building and the weather charts and you're done with the "will a heat pump be effective?" question.

sokoloff
9 replies
7h22m

Sort of. My house is 100 years old and was built without insulation (some rooms were insulated through remodels over the years). It uses water circulation and cast iron radiators and stays comfortable with my ancient cast iron boiler and 180°F water.

To know whether a heat pump (air-to-water) can replace that boiler effectively and maintain comfort, I had to find out whether the house would be comfortable with water temps of 135°F or so. Is there an amount of “that’s just looking at the building construction” to make that analysis? I think maybe technically yes, but practically no.

As it was, to get an answer, I abused my old boiler by turning the water temps down (causing condensation and slow damage [planning to replace it anyway]) and seeing what happened on cold days.

wenebego
4 replies
6h44m

You didnt need to do that, though. It peobably wouldve been easier to use manual j (or some software) to estimate the heat loads in the house, with given set points, using weather station data.

sokoloff
3 replies
5h45m

I can find/closely estimate the heat loss easily. What is much harder to find is the heat gain/transfer into the room from 1920s cast iron radiators at 135°F flow and the balance of the system flow temperatures at those 45°F lower flow temps than originally designed.

Then, because the answer is almost always going to be "yeah, it's going to be really close...", I felt well-advised to prove it via experimentation rather than commit to changing the heating plant to a system that could not provide 150°F flow temperature.

rainbowzootsuit
2 replies
5h8m

If you are ok with IP units the formula is 500 * GPM * delta-T for water as the fluid.

sokoloff
1 replies
4h17m

The question is not about the general hydronic heating formula [nor manual J heat loss estimations], but rather "what will the delta T of the rad in this particular room, in this piping network [it's a converted gravity feed system, now being a pumped], using 69°F room temp and 135°F leaving water temp from the heat source?"

brnt
0 replies
3h51m

For the, for lack of a better word, standard radiators there is a formula with a dT^4. But I totally agree, this isnt all that straighforward, given that for the dozons of installers, experts and home owners I have spoken, Ive heard dozens+1 methods for estimating. Estimating heat loss from a given building and estimating power output of a given installation of radiators, very few people seem to be able to calculate that.

If your heater can go low (mine bottoms out at 50 unfortunately), by far the easiest is to just test.

hojdra
1 replies
3h54m

What was the answer you came to? I'm in a very similar situation

sokoloff
0 replies
3h21m

Ref: https://news.ycombinator.com/item?id=39144329

A two-part answer:

From the Mechanical Engineering/Thermodynamic angle:

Ultimately, I proved to myself that a heat pump could work down to an outside air temp of about 18°F [which is slightly above our 99th percentile design temp] with flow temps of 135°F, so an air source heat pump could work with slightly reduced comfort on about 2% of days or could work all the time with supplementation with a 9kW [30K BTU/hr] electric boiler.

From the commercial angle:

What killed the project is no heat pump installer was interested in doing the work (as reflected by outright declining to bid, while bidding a 4-hour gas boiler swap, or by bidding so high that they might as well not have bid, while also cheerfully bidding a 4-hour gas boiler swap). So my house still burns gas for heat.

On the engineering front: I think the answer is often going to "<hissing inhale> It's going to be close; we should probably test it..."

ClumsyPilot
1 replies
6h36m

Don’t you want to replace the radiators with large vertical floor to ceiling radiators to get the same amount of heat transfer at a lowest possible temperature?

I am not familiar with the nuances, but this appears to be an equation with two variables - water temperature and radiator surface area. Maximising surface area should slow you to use lower water temperature. And the lower the water temperature, the more efficient the heat pump will be?

sokoloff
0 replies
5h43m

As a mechanical engineer, would I like to do that? Absolutely!

As a homeowner who bought a 1920s house because I like the character of a 1920s house, would I like to do that? Absolutely not!

brnt
0 replies
3h34m

Yeah no. It's become a bit of a hobby of mine, heatpumps. If I ask 5 experts/installers to take a look at a building I'll get 6 estimates, varying wildly. Plus, installers are still consistently over dimensioning and thus killing your sCOP, because they don't want customers to complain 'its slow to heat' and so on.

Calculating the heat loss of a house is really not trivial. Often you'll have no idea of the materials used or the quality of installation, and not really a way of finding out unless your up for some destructive investigation.

KeplerBoy
7 replies
8h10m

Heat pumps are reliable even in unfavorable conditions.

You will have to invest a lot more electrical energy and you might not be pumping heat as much as just converting electrical energy to heat, but let's not spread the myth that a heat pump will leave you freezing once outside temperatures drops below a certain threshold.

akira2501
5 replies
8h8m

A heat pump without a resistive heating /option/ will absolutely cease working below a certain temperature. They do, for whatever reason, sell systems that way in some regions.

jwr
1 replies
7h52m

Perhaps, instead of spreading FUD, it would be worthwhile to mention these "certain temperatures", so that people can make an educated decision of whether it applies to them at all.

I'm looking at the datasheet for my Fujitsu system and it is specified to work down to -25°C.

Does it lose efficiency when it's cold outside? Sure. But guess what, it's still more effective than resistive heating! I am starting from a SCOP of 4.89.

bluGill
0 replies
5h0m

The UNIT is specified to work down to -25. The SYSTEM includes the building it is installed in: the local climate, the size and heat loss of the building, how the install was done, and likely some other factors I'm not aware of. If you get less heat from the unit than you lose via other means the system isn't working even though it is delivering heat.

egberts1
1 replies
7h31m

Real question is does it prevent freezing? Like 100%. After all, the human body is quite resilient … above freezing.

I am thinking in Nome, Alaska where such heat pump could prove its versatility as an anti-freezing component of living quarters or even maintenance shed.

bluGill
0 replies
5h4m

Humans can put on clothing and be fine in very cold temperatures. However pipes cannot 1C is a hard minimum safe temperature, once it gets colder than that you risk pipes breaking.

KeplerBoy
0 replies
8h2m

That's true. Strictly speaking a heat pump doesn't need a resistive heating element, but I've never heard of units not containing that feature. After all it's dirt cheap and enables the reliability, we're discussing here.

bluGill
0 replies
5h6m

let's not spread the myth that a heat pump will leave you freezing once outside temperatures drops below a certain threshold.

That is not a myth - I have a heatpump in my house and it will leave me freezing on the coldest days. The system is sized so that it cannot keep my house warm at -5C (the system can deliver heat, but the house will cool down). Worse, it did get below -25C here for a couple days which is as cold as any heat pump will work - I don't know of any house that is insulated so well as to be warm when the outside temperature is below -25C for a few days without some heat - but mine isn't one.

A correctly sized heat pump can keep your house warm to -25C, but if the installer doesn't give you a correctly sized system it will not. Most installers don't know how to size heat pumps.

HPsquared
2 replies
7h55m

Ground source heat pumps don't have the icing problem. More expensive to install, though.

ClumsyPilot
1 replies
6h5m

I think this could be Resolved by scale, but that’s precisely what the west is really bad at

If we standardised ground source heat pumps as a must have all multi dwelling developments like apartment blocks and rows of terraced houses who could share one well et cetera, It would not be a noticeable cost at all

bluGill
0 replies
4h57m

Maybe, where are live there isn't much ground water and so no well can deliver enough water to be useful for a large building HVAC needs. There are a lot of ground source heat pumps around me, but they are all the coil in the ground style which doesn't scale the same way and so will be a lot more expensive to install.

oakesm9
21 replies
7h27m

A lot of these are UK based systems which are installed by installers with Heat Geek[0] training.

They're an interesting company who's trying to fill in the lack of training that traditional gas heating installers have to properly install air-to-water heat pumps in the UK. They also do homeowner training courses and a guarantee scheme on their certified installers (they'll fix the system for free if the SCOP is below a designed level).

They did a series of videos with Skill Builder[1] (who's a bit of a heat pump sceptic) where they fixed a badly installed heat pump that was causing a lot of issues. That install is currently 7th on the linked website[2] with a SCOP of 4.5 (450% efficient). Obviously a bit of a sale pitch from them, but there's loads of interesting information about WHY they're making the changes that they are.

[0] https://www.heatgeek.com

[1] https://www.youtube.com/watch?v=BesfqnHPxLU

[2] https://heatpumpmonitor.org/system/view?id=196

stavros
18 replies
6h3m

What's Skill Builder's skepticism based on? Don't heat pumps deliver on their promises?

bluGill
9 replies
5h40m

Maybe. However a heatpump sized to cool your house in summer cannot heat your house when the temperature is below about -3C. The heatpump might be able to produce heat to -25C, but it is too small to produce enough. Thus my system (in the US) that I just paid a lot of $$$ to install last fall leaves me using the backup gas heat a lot more than I wanted last winter which is disappointing. (It did get below -25C last winter for 2 days so I'd need that backup heat anyway, but I was expecting only 2 days not most of a month)

stavros
2 replies
5h38m

Hmm, that's interesting, we have fairly large temperature swings (typically -15 C in the winter to 40 C in the summer), so it'd be interesting to see if the heat pump could replace the AC unit and the gas heating.

glxxyz
0 replies
2h21m

I'm in a similar zone and replaced (delivered) propane with a ground source heat pump 2 years ago. Constant temperature indoors (3C warmer in summer than winter) with plenty of AC capacity to spare. Breakeven is about 5 or 6 years.

Glyptodon
0 replies
4h9m

They work okay in my area for -1C to 46C, imagine for your range maybe you just get a model that has improved heating over a basic one, whether that means ground source, more stages, or a heating element.

santahigh
1 replies
4h8m

I have this outdoor unit https://cooperandhunter.us/product/ch-hyp36lcuo. This past winter the temperature dipped into -20C (-11F), had no issues maintaining temperature in the low 70s in the house. I was running them in heat pump only mode (resistive strips were not used).

In the summer our temperature regularly reaches into 90s (above 30C) and the house is very comfortable on those days as well with the same heat pumps

bluGill
0 replies
1h56m

your heat pump is sized correctly for your house.

rainbowzootsuit
1 replies
4h59m

A properly sized system will be based upon the worst of the heating or cooling conditions.

Luckily an inverter heat pump can run down to about 25% full load so even with them coupled and in an imbalanced heat/cool environment you can still see good performance year round.

bluGill
0 replies
1h55m

Try to train the hvac profession of that.

pjc50
0 replies
4h23m

British note: UK govt subsidies for some insidious reason are not available to "reversible AC" style systems, so the dominant form here is air-to-water.

I had mine fitted last year. Retrofitted to existing radiators with 8mm pipework. With natgas backup/hot water boiler. At the end of this month I intend to go back and correlate the bills against the previous year (both kWh and £), because like a lot of discussion in this thread I think the installers have made some poor decisions. There's too much poorly insulated external pipework.

newZWhoDis
0 replies
5h36m

What are the following specs for your unit?

SEER2

HSPF

BTU

Feel free to post the model #’s as well.

stephen_g
5 replies
5h54m

Heat pumps require some domain-specific knowledge to build a system that costs less than gas for the same building (the crossover point is near a seasonal average COP of 4.0 at UK's gas and electricity prices, as mentioned in other comments SCOPs of 4.5 are very possible). Yet there are subsidies available and installers without the knowledge (who would normally be installing gas systems) are installing them basically without sizing radiators correctly or by doing things that reduce performance (big buffer tanks, lots of zoning, extra pumps that are unnecessary, etc.).

So there are lots of horror stories of companies installing systems that don't work very well and cost a lot of money to run, which makes people think heat pumps are crap. But usually people like Heat Geek trained installers can fix such systems without changing the equipment - often both providing more comfort than gas (less thermal cycling because heat pumps with inverters can modulate their output more precisely instead of hard switching on and off) and costing less to run than gas.

darkwater
2 replies
5h23m

What do COP and SCOP acronyms mean in this context?

stephen_g
0 replies
5h18m

COP is Coefficient Of Performance, basically the heat they produce divided by the electricity input, so a COP of 4.5 means that 1kW of electricity produces 4.5 kW of heat (it's taking heat from the environment so you can say a COP of 4.5 means it's running at 450% efficiency, but that's only in terms of electricity use, not actual overall efficiency - but electricity use is what we care about).

COP is only an instantaneous measurement though, and changes depending on the outside temperature. So if you need heating for five months a year, and it's usually exceeding COP of 5 for 80% of that time but dips down to a COP of 3.0 on the three or four coldest days of the year, it's not really correct to say it's either >5 or that it's 3.0 - so SCOP is used as a 'seasonal' COP that is averaged over a longer time period, so you can compare different systems over the longer term.

rainbowzootsuit
0 replies
5h14m

COP (coefficient of performance) is taken at a full load condition with specific indoor/outdoor conditions.

SCOP (seasonal coefficient of performance) is a weighted average of performance at different load conditions that represent different outdoor conditions based upon an average binning of weather conditions.

switch007
0 replies
2h38m

Most if not all energy/green subsidy schemes in the UK in the past couple of decades resulted in tons of cowboys rushing after the gold, and doing a terrible job and even causing serious long-term damage to the property.

No different this time round I imagine.

It's so infuriating - literally handing money to conmen

stavros
0 replies
5h41m

I see, thanks. This provides a counterpoint to the sibling comment of "they don't perform but everyone blames the user for doing it wrong", but also sounds true, so hopefully as installers learn more about how to correctly install heat pumps, they'll perform better.

cameronh90
0 replies
3h26m

I've watched a few videos of his and I'm not sure I'd characterise him as entirely skeptical of the technology as a whole, but more skeptical of the government incentives to retrofit.

He argues in one of his videos that there aren't enough qualified installers who actually understand heat pumps, and the government incentives are encouraging cowboys, basically, to take the government cash and provide unsuitable installations. Then secondly, a lot of the insulation installers also don't know what they're doing and are creating damp problems by neglecting ventilation.

Even as someone who is a huge fan of heat pumps, it's hard to disagree with him. There are a lot of difficulties with retrofits in the UK, where we have a lot of old terraced housing stock with poor insulation, no mechanical ventilation, and small gardens. Then on top of that, there are almost no tradespeople who actually understand the technology or why that housing stock is unsuitable without extensive improvements.

To be frank, even regular gas plumbers are shocking here. They don't install correctly rated systems, don't set the temperature correctly and don't enable the weather compensation functionality that is built into all modern combi builders and can save you 30%. They just install an over-sized boiler and whack the temperature up to maximum. At least it keeps the house warm, at the cost of inflated bills. That's without getting into the FUD about chemical water softening (and use of magic magnetic "water conditioners" instead), continued use of loft header tanks and not understanding how to improve or balance water pressure.

beanjuiceII
0 replies
5h43m

No they don't and it's kind of like agile everyone tells you it's not done the right way otherwise it would work. But when is sold it's sold as is it's great.. Very deceiving for customers

naraic0o
0 replies
6h19m

it's funny actually, i've been binging their videos the past few weeks, since i'm looking into buying a home in need of renovation, and was happy to see their logos as part of one of the default columns.

they claim also to be mainly motivated by the climate crisis and are even, now, developing an open source water heater, which... you don't often hear about in industries such as home appliances or heating: https://www.youtube.com/watch?v=uFBbArwAXS8

i'd love to install an air-to-water heatpump myself, but i'm untrained and i guess i'm feeling a bit of the dunning–kruger effect while learning from the heat geek videos.

jillesvangurp
0 replies
3h56m

I watched a few of their videos as well. Great stuff. Key take away is that there are a lot of installers that have no clue what they are doing. Which results in poorly performing systems. The issue is not the technology but the lack of training and experience.

Another good point is that even an old house with poor insulation can benefit from heat pumps. It just depends on sizing things properly and dialing things in properly. The UK has a lot of old houses that are quite old. This doesn't have to be a show stopper. There are a lot of myths and half truths around this topic. Of course you'll need more kwh for heating if your insulation is bad. But you should still get the same energy coefficients. And you'll pay a fortune in gas as well to get the place warm. Whether that's worth it with or without investing in insulation, windows, new roofs, etc. depends on a lot of things.

Most of the nonsense about heat pumps not working at lower temperatures is easily refuted by the notion that much of Scandinavia runs on these things for decades. Most of the people having issues with heatpumps are simply buying the wrong stuff, or having it installed wrong, or both. People have proper arctic winters in Scandinavia. Also there's a reason lots of Scandinavians ended up in places like Montana: it feels like home to them but with better summers (it's much further south). If people can do heat pumps in northern Norway, Montana is a walk in the park.

class3shock
11 replies
1h38m

I just want to throw this out there to this audience. As someone that has worked in and been interested in energy efficient housing for 10+ years, I have been heartened to see the start of proliferation of heat pump units. However, as a whole, the market seems to be flooded with units of as good quality as your normal store bought air conditioner. That is to say, as soon as something goes wrong with them, they are garbage.

How come we only talk about efficiency/environmental friendliness of use and not of the unit itself (and all it's embodied energy/cost)? If I save 60% on energy for heating every year but then require all the energy needed to build a new heat pump every 5-10 what am I really doing?

I would love to see an effort to create an open source heat pump itself, based off of COTS parts and raspberry pi or something similar where you are not locked out of the software and dependent on a supplier to have replacement parts that they probably stopped stocking 5 years after releasing the product.

the__alchemist
2 replies
1h17m

Hey - I've been following the steady stream of articles and discussion here about heat pumps, so I have a question that is tough to answer from the articles.

Is heatpump popularity regional? My understanding was that heat pumps are the technology behind residential AC, heating, and commercial HVAC. Thermodynamic 4 step cycle of a working fluid with expansion, compression etc. Every house I've lived in has had one. The cycle is reversed to cycle between heat and AC; dumping the heat to one side of the system or the other depending on need, as controlled by the thermostat.

What is the alternative? I've seen in (new and old!) England they use natural-gas radiators sometimes, and have no AC, or window AC units. Is that it, and now areas with those are switching more to heatpumps? Or is it new, more efficient heat pumps? Or do I have a misunderstanding of the existing tech?

tnorthcutt
0 replies
56m

I would venture to guess that most residential heating in the world is provided by non-heat pump sources.

In many parts of the United States, my understanding is that it would either be natural gas fired furnaces with forced air, oil fired furnaces (with forced air? not sure), radiators (with water heated by gas or oil fired furnaces), or electric resistive heating elements (e.g. baseboard heaters).

Robin_Message
0 replies
44m

UK is almost exclusively hot water radiators heated by natural gas boilers (or oil boilers in rural areas not on the gas grid).

There is a push by government to switch to electric heat pumps driving hot water into larger, cooler radiators (as this is more efficient for the heat pumps), backed by a £7500 grant for the pump and installation (with limited take-up).

danans
2 replies
44m

That is to say, as soon as something goes wrong with them, they are garbage.

Can you unpack what you mean by this? Standard A/C's can be repaired - fans can be replaced, as can compressor motors. Also, better and more efficient heat pumps can be more sensitive to maintenance (or lack thereof), because they often achieve that efficiency through finer control of mechanical components or lower resistance components.

IMO, a bigger factor in the longevity of traditional A/Cs is that they tend to have single-stage compressors that are over-sized for their loads most of the year, resulting in short-cycling and therefore shorter equipment life.

pstrateman
1 replies
21m

It's quite often cheaper to purchase a completely new unit than to fix an old unit.

Factory supplied parts disappear fairly rapidly after products are end-of-life and labor to repair can be quite expensive.

semi-extrinsic
0 replies
4m

This is true.

We have a decent-quality Mitsubishi unit that's 7 years now. Last year, one of the main boards died. Living in a country with strong consumer protection, I was able to argue my way into having Mitsubishi cover the cost of a new board, I just had to cover labour.

If I'd had to cover all the cost, it would have been more than 40% of the cost of a new unit, and then you start asking yourself if it's worth it.

Even though the marginal cost of the main board is likely below $50, the replacement ones sell for close to $500.

tsss
0 replies
11m

If I save 60% on energy for heating every year but then require all the energy needed to build a new heat pump every 5-10 what am I really doing?

Activism.

londons_explore
0 replies
1h24m

Quality cones with design refinements learnt after the technology has been in people's homes for decades.

There is nothing theoretically unreliable about a heat pump - it would totally be possible to design it to work for 50+ years with just basic filter replacements.

jjeaff
0 replies
58m

I would be interested to see the math on replacing a cheap unit every 10 years versus an expensive unit that lasts 30. A few years ago, we replaced our 30 year old Carrier system with a new heat pump system that was relatively inexpensive. But here's the thing, the old system was not nearly as efficient from the beginning and it was much less efficient 30 years later. I'm not sure how much room for improvement there is with the new heat pump systems in regards to efficiency, but if the advances are significant every 10 years or so, it may net out to a positive.

Pxtl
0 replies
1h22m

store bought air conditioner

Yup. Saving the world is going to be ruined by Chinese shovelware-quality equipment re-stickered with American brands, but in this case it's even worse since you're hiring a professional installer and those guys will only work with a short list of manufacturers, so getting somebody to install an expensive quality European model will be basically impossible (if they're even certified for use in North America).

Kerb_
0 replies
1h26m

If I save 60% on energy for heating every year but then require all the energy needed to build a new heat pump every 5-10 what am I really doing?

As good quality as your normal store bought air conditioner. That is to say, as soon as something goes wrong with them, they are garbage.

Sounds like you're still saving 60% on energy because the status quo is also disposable appliances. It absolutely sounds better than nothing to me, but I am also hopeful for more maintainable and accessible heat pumps in the future. I haven't heard about any efforts for an open source heat pump, but I'm definitely interested in something like that myself

phkahler
5 replies
8h8m

Isn't the "crowd sourced"? It's not open source.

tikkabhuna
2 replies
7h51m

Is that just the website? Is there a way to export the raw data?

wanderingmind
0 replies
7h44m

+1 yes we need a way to export and analyze data to get the insights we want. Would be great if we can share through Datasette which is tailor made for such applications

naraic0o
0 replies
6h7m

there's an export button at the bottom of the table which copies a CSV to your clipboard.

phkahler
0 replies
5h8m

The heatpump performance data looks crowd sourced. If the website and DB are run with open source software, that's a different thing and seems secondary.

stephen_g
4 replies
5h25m

Really shocked at those prices, I really don't understand what's going on in the US/Canada. I could get a 7kW Mitsubishi Electric single-head mini-split installed with change for AU$3000 here (US$1950) if I buy the unit online and get one of the many, many installers around to put it in (fairly simple install if it's near an external wall is around AU$750 at the moment), but that document has prices in the $7K to $12K for that size?!?

bluGill
1 replies
5h11m

Which is why mini splits are not very popular here. The install ends up costing so much. Labor is not cheap in US/Canada, and install is a lot of labor. Still seems like it should be cheaper though.

dalyons
0 replies
41m

Labor is even more in australia, so that's not what's going on here.

kleiba
0 replies
2h32m

Wait until you see prices in Germany...

Sytten
0 replies
5h18m

I paid 15k CAD for 2 Daikin units two years ago, the pricing is kinda stupid but it depends on the quality of the model. Chinese models are way cheaper than Japanese models.

dopylitty
4 replies
4h41m

This guy[0] has done quite a few deep dives on heat pumps that cover a lot of the myths (eg they don't work in the cold). It's pretty interesting material if you're thinking about a heat pump.

It has always seemed silly to me that we spend money to keep a box of cold (fridge) inside the houses we're spending money to heat in the winter and spend a lot of money to heat up dryers, stoves, etc in the houses we're spending money to cool in the summer.

Watching these videos made me think there's a real possibility at some point to have something like a whole home heat pump that just moves heat from where it is to where you want it and in the process reduces the need for systems working against each other to heat/cool specific parts of the house. I understand there's something in commercial settings that has this capability but I'm blanking on the name.

0: https://www.youtube.com/watch?v=7J52mDjZzto&t=0s 1: https://en.wikipedia.org/wiki/Variable_refrigerant_flow

FredFS456
3 replies
4h13m

My parents have always had an "outdoor fridge" that is a stainless steel equipment box that my dad salvaged from the junk pile at work. They put food in there that is less prone to spoiling, and use it through the fall/winter/spring months.

dopylitty
2 replies
3h51m

That's a great way to keep the raccoons out!

If I make a big pot of soup in the winter I will cool it down outside before putting it in the fridge. That way it gets down below the zone where bacteria grow much faster than if it were inside.

From an energy perspective it would be better to put it in the fridge so the heat would be removed by the fridge and stay in the house rather than dissipated outside but as far as I know the heat would also end up in the other goods in the fridge causing potential spoilage. It would be nice to have some kind of remote chiller pot hooked to a heat pump that would just pump the heat out of the soup and into a cold room.

brnt
1 replies
3h40m

heat pump that would just pump the heat out of the soup and into a cold room.

You already have one, it's your fridge ;)

dopylitty
0 replies
3h30m

Right! The problem is before the heat gets to the room it sits in the milk for a while and raises it to temperatures where bacteria like to be.

changadera
3 replies
4h15m

My neighbour has a heat pump and it's kind of annoying when running because the 180hz hum is audible in most of the rooms in my house. This in the UK and our houses are detached, but fairly closely spaced.

dv_dt
1 replies
4h12m

I wonder if there is some isolation dampers that could be added to the mounts (sounds fancy, but think rubber or silicon grommets).

timbit42
0 replies
1h57m

Most heat pumps mounts I've seen have rubber grommets but older heat pumps will make audible noise as they wear out.

switch007
0 replies
1h53m

A constant hum from a neighbour's heating unit would drive me crazy. We have lots of terraced and very-close-together housing in the UK...

Low frequency noise can travel quite far (and through mass), so not even distance helps that much

cess11
3 replies
7h9m

Where I live every other house is heated by either air-to-air, air-to-water or soil-/ground-to-water heat pumps. -20C a large part of winter isn't uncommon, some places go even lower.

So to me it looks a little bit insane when people confidently claim that heat pumps are unfeasible in rather cold climate.

The best conditions for heat pumps are places with hard rock just below the soil, so you can drill a heat well and use it for heat storage during summer months, i.e. AC/cooling. In my opinion that's the main drawback with air- and soil-based heat pumps, can't recycle heat from cooling in the summer.

__MatrixMan__
2 replies
5h20m

Is the kind of well that you'd typically drill for a single family dwelling capable of storing enough heat to make that worth it?

I know that underground heat storage is popular with district heating, where you've got a hollow mountain storing heat for the whole city, but the square-cube law means that there's a size below which it doesn't make sense. I had only assumed that that size was bigger than was feasible for a typical homeowner.

cess11
1 replies
4h55m

Don't need to use cooling to make it work, I live in a fairly large house without cooling and a bore down into the mountain below is good enough even though we have -15 to -25C for weeks during winter. It's in a small town so not an isolated location. Most people around here have air-to-water or air-to-air, because it's good enough and cheaper to install.

And it's not a hollow, it's a plastic ~1 decimeter pipe with ethanol going through stone some distance down from the surface. Not sure how long this collector is, but 70-200 meters is common depending on how large the house is and conditions in the ground.

__MatrixMan__
0 replies
3h42m

Interesting, thanks.

Ethanol is an interesting choice... lower specific heat when compared with water. Is that to discourage things like tree roots from making a home in your well?

carnot
3 replies
8h11m

Certified performance rating data from virtually any air-to-air, air-to-water, etc., system sold in North America is available here [1]. This includes capacity, COP, and sound data. It also includes integrated performance rating metrics like SEER, HSPF, IEER, etc.

[1] https://www.ahridirectory.org

sokoloff
1 replies
7h51m

As-engineered and as-installed/configured figures have the potential for a wide spread. Both are useful, but as a homeowner, I’m interested in seeing my as-installed figures more than the manufacturer or test lab’s figures.

As a shopper, I’d want to see a nearby house’s figures as-installed by my prospective contractor.

Haemm0r
0 replies
5h50m

A big factor for the total energy consumption besides the heatpump is the rest of the heating system. For our house the yearly energy consumption of the heatpump is around 1.4MWh/y (for floor heating, warm water and cooling of the bedrooms in summer;this number is reported by the heatpump control system) but the hole heating system including all the pumps and so on is 2,55MWh/y.

rainbowzootsuit
0 replies
5h18m

It's important to note that those ratings are all tested under specific conditions that includes a rather short (~3m IIRC) lineset and other parameters of installation that in the field can lower the capacity as more energy goes to the pumping of the liquid refrigerant. Particularly the lineset length.

Also, the testing varies between "traditional style heat pump" and inverter driven "VRF" equipment.

That's not to say that the AHRI information isn't useful, but the numbers can be a little subtle to get to an apples to apples comparison and you should have a selection done based upon some real estimated line lengths and installation conditions.

willcipriano
2 replies
3h18m

Anyone make/is it feasible to make: a window unit heat pump?

apexalpha
1 replies
3h15m

Midea Window AC is what your looking for I think.

werdnapk
2 replies
6h54m

Just got a Daikin heat pump installed this past winter. Electric furnace is still used as a secondary heat source. Will have to compare more data over the last 12 months, but so far, power usage is way down.

I can also integrate home assistant with the Daikin which can control all of the functions and it's also able to retrieve a lot of useful data that you can use for adjusting furnace and heat pump parameters. I can get credit from the power company during peak usage times and I'm able to have home assistant interface with the heat pump to maximize those credits as well. Very happy with the setup so far.

janten
1 replies
6h28m

Can you share what you use for the HA integration?

trebligdivad
2 replies
7h17m

How are the COP values so high? The spec on the Vaillant aroTHERM+ says ~2.9 but that is showing well over 5 on some; what's the difference?

jnsaff2
1 replies
6h50m

COP depends on the temperature difference.

A single COP is some yearly average usually but in these measurements it is probably a shorter period.

In europe there is a somewhat more rigorous measure of Seasonal COP (SCOP) where the typical climate (in my case nordic) is taken as a standardized test. So x number of days outside temp 0C, y -5C, z -10C, w +10C etc.

So in case of Air source heat pump if the outside temperature is +10 or +15 you can easily get COP numbers that are 9 or above.

Better technical documentation usually has rated COP for some different outside temperatures or even a graph.

Kichererbsen
0 replies
6h45m

note also, that the temperature difference is also influenced by the outlet temperature: if you have a radiator system, you'll need a higher outlet temperature than say a floor or ceiling heating system. this is because the energy transported is proportional to area of the delivery system. so that's also something to optimize. add in a decent insulation (less units of heat required to replace lost heat units) and you get a higher COP.

joshlk
2 replies
2h14m

Is there an explanation of the acronyms/metrics used? E.g. COP

timbit42
0 replies
1h54m

COP or CoP means co-efficient of performance. An electric heater has a CoP of 1. New heat pumps usually have a CoP of 4 or higher. My 11 year old heat pumps have a CoP of 3. This means they can produce 3 or 4 times as much heat as an electric heater, assuming the same amount of electricity, or produce the same amount of heat with 1/3 or 1/4 of the electricity.

At a CoP of 3, they are more efficient than electric heaters down to -15C. At a CoP of 4, down to -25C. There are better heat pumps coming with a CoP of 5.

Cort3z
2 replies
1h4m

I recently had to get a replacement heat pump. In the process I discovered that the EU has a database of energy ratings for almost (actually?) all electric appliances sold in the eu. This includes heat pumps.

I scraped the heat pump data and am the proud owner of 100% of this information. What I found is that some of the available data is inaccurate and much of the energy ratings (A-G character rating) is inconsistent with the performance of the device, probably due to changing standards over the years. It’s nice to see initiatives like this which hopefully will provide better and more normalized data.

As a side note. Air-to-air heat pumps have, as most people know, two parts to it. The indoor unit, and the outdoor unit. Many models can be used interchangeably, so the domain of heat pumps is a bit more complicated than I first anticipated.

jonasdegendt
1 replies
1h1m

To my knowledge, the A-G energy rating is a rolling standard. It gets a little bit tougher to make A grade every year.

NCAP works the same way.

Cort3z
0 replies
54m

Indeed. The data available includes most of the things you would expect, but some of it is just wrong. I’m only at my computer now, so don’t have a concrete example, but some models had vastly higher values for some fields than is possible.

supermatt
1 replies
2h32m

I love my ground-source heatpump. I did the entire install myself, submerging the loop in the pond by my house. We get a COP of approx 3.0 in the middle of winter when its -25C air temp outside :)

WaitWaitWha
0 replies
2h9m

do you have your setup documented online somewhere public?

rq1
1 replies
8h55m

This is a great initiative!

Especially now with all the integrated circuits and sensors, we can have a clear picture on the products if we could all share these data.

I’m looking to get a heat pump too and was leaning towards the NIBE make that these data seem to validate. (They’re incredibly silent too!)

brabel
0 replies
8h8m

I have a new NIBE pump (S735) that replaced my old, also NIBE (Fighter 640P) pump. It's a bit more silent than the older one usually, but sometimes it starts what sounds like a jet engine which is pretty loud. I can hear it from upstairs, far away from the pump, coming from the vents. I am not sure what it's doing when it makes that noise but it made me a bit upset with it, as initially I had hoped for a quieter house, and the pump was pretty expensive!

matznerd
1 replies
3h16m

I love to see Hacker News geeking out on heat pumps and that this is currently on top of the home page!

Don't forget that this community has an outsized influence on the world as early adopters and innovators.

kleiba
0 replies
2h34m

Heat pump technology is certainly out of the "early adopters" phase. It is basically the standard for new buildings in Europe (at least Northern Europe, I'm not sure about the South), and has been for years.

In Germany, where I currently live, they recently passed a law that constrains what kind of heating system you're allowed to put into your house to a point where basically only a heat pump fulfills all criteria (perhaps with the exception of pellet heaters).

zmully
0 replies
4h46m

What would make this even more useful (if possible) would be including 1) the UK equivalent of an ASHRE Manual J and 2) an ACH rating for the dwelling.

Heat pumps are great, but suffer from piss-poor installations and shitty salespeople. When I renovated my DC rowhouse, I talked to 6 different companies about the HVAC install. Only one, ONE, would do a Manual J. I had already done a Manual J myself (it's not hard at all) so I could compare their calculations to my own. They were slightly different (they calculated a greater load than I, but at the time, the insulation systems I used in the house were uncommon, so most of this difference was due to their lack of familiarity).

In the end, my rowhouse needed such a small unit (1.5T IIRC) that I couldn't get the SEER I wanted because no one makes high end units that small... I ended up slightly oversized at 2T, but that was necessary to get a unit from a good manufacturer (Lennox), rather than a pile of garbage flipper grade unit from someone like Goodrich.

What the heat pump industry is going to suffer from is the utter and blatant disregard to right-sizing units. The other 5 companies I talked to? They just walked around the house and then said shit like "This gonna need a 5T unit" and left.

Also, flex duct is bane of any central non-high velocity system. If an installer mentions flex duct for anything other than a short run to a register, run away from them. Flex duct is the sign of a lazy installer who is going to cut corners everywhere else they can, and especially where you can't see it.

In the same vein, if the installer doesn't have their own sheet metal shop, make damn sure they're buying your ductwork from a sheet metal shop and not from HomeDepot. One company I interviewed refused to do a Manual D (duct sizing) and said that a standard (i.e. we're going to get it at HomeDepot) 9x13 duct will be "plenty" for the return. The return (per the Manual D) ended up barely fitting in the chase alloted for it which is something like 30"x 24".

So be educated consumers:

- Do a Manual J and Manual D yourself, they're not hard

- Right size your unit. It should be running 90% of the time for max efficiency, so yeah, a smaller unit might take longer to cool or heat, but you shouldn't be turning the unit on or off but two or three times a year. A super high efficiency unit that is oversized is going to be terrible and inefficient. Don't fall for their shitty sales tactic of "but it's not going to be able to cool your house down as quickly as this 5T unit!".

- Demand good work. Like a plumber, never ever ever let an HVAC installer in your house unmonitored. I had to fight with my installers because they wanted to move a chase to the middle of the room "because it'll be easier for us". No, you have the plans, you quoted on the plans, so I don't give a shit that it's hard.

- Insulate and seal your duct work. You can't go back and do this, so make sure it's in your contract, and make sure they actually do it.

- Make sure you service your unit annually, it's a couple hundred bucks of peace of mind.

wenebego
0 replies
6h39m

It would be nice (but potentially difficult) to add the sensible and latent capacity for heating and cooling given 3 design days: humid, hot, and cold. The btu ratings are useful to compare efficiencies but not sizing the system

tgtweak
0 replies
43m

How is the heat output calculated and validated?

qsdf38100
0 replies
1h1m

Are all the compared heat pumps working at the same temperature levels? Otherwise, the COP isn't a good comparison metric, as even for an ideal heat pump with a COP = 1 / carnot_efficiency, it depends on the temperatures.

For instance, a heat pump lifting heat from 20°C to 100°C with a COP of "only" 2 is excellent, whereas lifting heat from 20°C to 30°C with a cop of 3 is not impressive.

nirolo
0 replies
4h3m

A very big database comparing a lot of relevant data can be found at https://www.eurovent-certification.com/

I only used it for air-to-air heatpumps (or air conditioners as they are sometimes called). He the data is oretty good. I can't say anything about the other types of heatpumps but I've found the database quite useful.

meigwilym
0 replies
7h40m

Great to see a local project at the top of HN! Good work guys.

henearkr
0 replies
8h37m

Awesome initiative! I really appreciate it!

Some (hopefully) constructive critics to make it even better:

- fix the left side menu, so that, even when the "Add fields" part is displayed, it can be scrolled up and down (because right now if I unfold "Add fields" and further unfold some of the items inside it, the content becomes hidden below the bottom border of the screen)

- add noise level information (the noise level of the compressor), in dB. Some manufacturers don't provide this info, so it would be really useful to gather it here.

danans
0 replies
2h54m

It wasn't clear to me what kind of monitoring equipment is being used to gather this data, or whether it's just being manually gathered and reported by each system owner.

If the former, I'd like to get the generic equipment to use to monitor my heat pump system, and if the latter I wonder if the resulting inaccuracy results in improbable outliers like the system with 6.0 COP.

EDIT: it's a bit buried, but the systems are monitored using Open Energy Monitor (https://docs.openenergymonitor.org/applications/heatpump.htm...), and it seems like heatpumpmonitor.org was created by them.

apexalpha
0 replies
3h48m

How do these people monitor the heat output of the heatpump? Is that something you can get from the device itself?

I recently installed a Nibe S2125 in my house, it's been running great except I don't monitor electricity consumption of just the heat pump, nor do I know how to get the heating output.

I somehow doubt all these people have a specific electric meter on their heatpump, or do they? Mine runs on 400V and the meters are a bit expensive to get just for the data.

adev_
0 replies
2h5m

My still-running heat pump from 1981 is not in the list. Unacceptable ! :)

Sytten
0 replies
5h22m

If you are in North America, I highly recommend to check out https://ashp.neep.org/#!/ to compare heat pumps. It has efficiency and technical data on almost all models easy to compare without the marketing bullsh*t of manufacturers. The tests are conducted independently and instead of one COP you get the COP depending on the outside temperature which very important in cold climates like Canada.