Heat pumps are obviously great in many ways. But fitting one is a big deal - they are quite expensive, they take a lot of work to fit, really require extensive additional insulation, and there are all sorts of caveats to them that mean they aren't a straightforward replacement for a boiler.
So i'm slightly mystified that we basically don't hear anything about fitting drainwater heat recovery [1], in which the lukewarm drain water from your shower is used to pre-warm the incoming cold water. It's extremely simple, pretty cheap, simple to fit, and can recover ~50% of the waste heat, of something which is tens of percent of the energy consumption of a household.
By all means, get a heat pump. But get a heat exchanger on your shower first!
> But fitting one is a big deal - they are quite expensive, they take a lot of work to fit, really require extensive additional insulation
I think this somewhat overblows the complexity of a heat pump.
They are simply Air conditioners that can be ran in reverse. One valve is the difference between a heat pump and AC. Why they are so expensive is really just price gouging because they aren't as common.
If you are in a home with forced air AC then installing a heatpump system couldn't be simpler and should be something you consider when updating your AC system. It's really just a matter of updating the compressor and maybe adding some smarts to avoid condensation. In fact, it's shocking to me that AC -> heatpump conversion kits haven't hit the market.
> So i'm slightly mystified that we basically don't hear anything about fitting drainwater heat recovery [1], in which the lukewarm drain water from your shower is used to pre-warm the incoming cold water. It's extremely simple, pretty cheap, simple to fit, and can recover ~50% of the waste heat, of something which is tens of percent of the energy consumption of a household.
Really interesting idea, but I assume you have to rip up the shower to accomplish this right? Also, I'm guessing clogged wastewater piping might be an issue right? That said, that'd be easily overcome by just running the lines side by side with maybe a simple copper connector for heat exchange.
What is mystifying to me is why governments allow air conditioners without that reversing valve to be installed. A simple change, and the more people installing a heat pump the cheaper those valves get.
Agree with your take. Recently helped install a heat pump at a single-family home (rental property) in the SF Bay Area. Actually, they aren't that much more expensive than AC's (mine cost about $9k for everything, but again, I did 35% of the work myself for a ducted 3 ton heat pump). And yeah, the installation is almost exactly the same as what you'd do for an AC.
And, you don't need to add insulation, but we did (to the crawlspace), costing about $2.5k
And, it's been running for about 3 months, and saved about ~$175/month in heating. wow. It'll pay for itself in about 7-8 years.
This sounds like an American viewpoint. In Australia, New Zealand and much of Europe they are pretty cheap to install, and rarely require additional insulation.
It may be that they're relatively new to your area, so the demand is outstripping supply of installers who have been doing this for 30+ years and as such are charging to that effect.
> Information obtained from the US Census Bureau’s Survey of Construction (SOC) and tabulated by NAHB, shows that the rising trend of single-story homes reversed in 2021. The share of single-story homes decreased in 2021 and the share of two or more stories homes started was greater than one story homes. This is in line with recent NAHB analysis of new single-family home size trends.
Speaking of heat pumps and water heat, I installed both a heat pump and hybrid water heater to save on electricity. The water heater doesn't seem to have made much of a difference in my electrical bill, my guess is the problem is peak demand so I should have gotten a much bigger tank than before. Ambient garage temperature may also be an issue but it exhausts outside and the garage is insulated so it generally stays above 55 degrees.
they also aren't very hot and wont work in northern cities, but people will install them there anyway. "boiler" - is that jargon for multiple kinds of heating units or actually just boilers?
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
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.
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
>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.
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.
Did you consider putting up solar to counteract the additional electrical load? Sure it would take 7-10 years to pay off the solar asset but after that its free electricity and heating. Something I'm playing with but its a bit more difficult in the city.
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.
> 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.
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.
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.
>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.
-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.
> 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?
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.
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.
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...)
At low temps COP is lower, meaning you'll not get 4 units of heat for 1 unit of energy spent, but COP is still higher than 1 meaning using heat pump is still cheaper than using basic electric resistive heating.
I think Northern England climate is ideal for heat pumps -- it never gets too cold, never gets too hot.
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.
> 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.
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.
> 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.
It's not just an environmental consideration - efficient houses are much more pleasant to live in, particularly if they are designed holistically with proper ventilation systems and few cold spots.
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.
> 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.
> 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!
> 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.
> 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.
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.
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.
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.
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.
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.
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.
> 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.
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.
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.
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.
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.
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.
> 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.
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.
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.
> 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.
That's right. I remember a local "electrification festival" where some vendors and city officials teamed up to explain the various options. One of the most common questions was "will this lower by bill"? And the most memorable answer by a vendor was "probably now, but you won't have to be wearing that coat in your living room". Which hit home because at the time we had a drafty house with poor heat distribution.
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.
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.
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
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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)
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.
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
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.
I see tables, I am exited. But I can't make sense of what anything is? I know COP, but what is Training, what is Source? MID seems to be a kind of sensor? Some of the table headers have a tool tip explaining things, but are the ones that aren't the most needed. Also, some about page about what the table aggregates and how it gets there? Seems to be some kind of aggregator for information gathered from an appliances called "emonHub" which is a rPi that gathers data from an assortment of other devices. There are some jargon that you have to parse, ("supply" means the electric cables that "supply" your heat pump) to understand what's going on.
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.
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.
Individually that's one way to look at it that makes sense. On mass scale though, if in 10 years someone can make one that's 50% better, it still behooves the world for the the units of today to last 50 years because even by then you won't have manufactured enough for everyone to have heat pump, let alone the most current one. Another way to think about it is imagine if instead of your unit dying in 10 years when you got a more efficient one you sold it to someone who didn't have one yet.
In general though, it's more the idealogy that gets me. It would be so easy to do a little more work to make things repairable, to use common parts, and ultimately create units that could last decades instead of lasting until an electric board has a short from dust or a pump predictably dies just outside of warranty, taking out an otherwise perfectly functional unit. It's just not viewed as the most profitable way, atleast not with how most people buy things today.
I think it could be profitable though, if you get enough people that can do the math and realize that over a lifetime it's cheaper than I think you could make that work. Additionally, it's not just about the cost over time but what happens when failures inevitably happen. Try having a repair done on any appliance today under warranty. First you have to go through the company and you get whoever they send and then you need their parts, if they are still available, which often they aren't. If the documentation on how to repair/maintain is opensource then you could potentially get anyone to fix it and if the components are COTS were possible then you aren't screwed when your 5 year old heat pump has an electrical failure because you can just but a new board (raspberry pi lets say) flash the software and install it.
> 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.
Just because something "can" be repaired doesn't mean it makes sense to. With most appliances if you are going to hire something to fix it outside of warranty it will cost hundreds of dollars at a minimum and you are often not guaranteed a repair will work. Even if it is in warranty, often a replacement part will be needed that is not available or is not economical to have a person install versus replacing the whole unit and the company will just scrap the whole thing and give you a replacement (after you've spent hours on phone calls, emails and talking to technicians).
The most egregious example of this I will highlight is electronics. Ask any manufacturer to provide a replacement board for an otherwise functional heat pump, air conditioner, etc. They likely won't have one. And even if they do, are you now going to hire someone to replace it? Do it yourself? If you aren't mechanically inclined its option one which can be hundreds of dollars and if its option two you will now be doing it likely with no or poor documentation spending how much of your time?
Heat pumps are no more sensitive to maintenance than air conditioners (besides the use of longer hoses for the refrigerant movement giving more opportunities to generate leaks). Or atleast their nature doesn't mean they inherently need to be (maybe that's the better way to put it). Compressors, fans, radiators, inverters, these are things that have been made for decades and if you walk into any commercial manufacturing space you'll find examples last for decades. That level of quality just isn't offered for homes.
You are absolutely correct that over-specifying heat pumps is also a big issue. That's kinda've a whole nother topic though that we could get into along with energy modeling, regualtions/practices, etc.
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?
The houses I've been through in the Midwestern US typically have forced-air natural-gas furnaces and cooling-only non-reversible central AC. Burning natural gas is way cheaper (ignoring externalities) to generate heat than even a heat pump, and can be easily scaled up to provide tons of heat on really cold winter days. Plus, modern heat pumps are high precision, complicated, expensive tech, a furnace is old tech: just a burner and a blower.
My natural gas cost is $0.82/CCF or $0.028/kWh. Electric is $0.161/kWh. That means a heat pump needs to be 575% efficient to break even on energy cost (assuming my furnace is 100% efficient, it's not, a lot of heat goes out the chimney).
People only get heat pumps here if they're carbon-conscious.
In my area in the midwest, nearly every house has a natural gas burning forced-air furnace for the winter and a standalone air conditioner for the summer.
Newer heat pumps have gotten a lot better, and as a result a few people are starting to use them here. Even so most heat pumps are the more expensive type that rely on geothermal coils. We have extreme seasonal temperature changes that make older heat pumps impractical. For about two weeks each winter, our overnight lows are around -20F (-29C) and we often see wind chills around -40. Summer temperatures regularly reach 100F (38C).
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).
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).
Thanks for the info on this! It sounds like my experience has been biased by coincidence. Ie, I've only lived in a house that was wired for gas once! (Northern VA). My childhood home (Also northern VA), both places in North Carolina, and Florida have all been heat-pump based, with no gas line.
My apartment in the UK was even weirder: It had something called a "Economy 10", with an electric heater (resistance?) in a concrete slab under the floors that would run at night, then release heat slowly throughout the day. (No A/C)
In the US heat pumps have only seen widespread adoption in the last decade or so and even then mostly in new construction applications. Most houses still use either window or central AC units and then some other mechanism for heating, oil or gas furnace, electric baseboard, etc.
>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
Where are you seeing this? Mini splits have been in use for a long time and just about all cheap brands are rebadged Gree and Midea, which are reliable and in use all over Asia.
IMO, the problem is that HVAC companies in the US overcharge so much for install/labor that homeowners are more inclined to replace them. They won't touch mini split brands that they don't install (and generally only install expensive brands)
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.
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).
Readit News
So i'm slightly mystified that we basically don't hear anything about fitting drainwater heat recovery [1], in which the lukewarm drain water from your shower is used to pre-warm the incoming cold water. It's extremely simple, pretty cheap, simple to fit, and can recover ~50% of the waste heat, of something which is tens of percent of the energy consumption of a household.
By all means, get a heat pump. But get a heat exchanger on your shower first!
[1] https://www.energy.gov/energysaver/drain-water-heat-recovery
I think this somewhat overblows the complexity of a heat pump.
They are simply Air conditioners that can be ran in reverse. One valve is the difference between a heat pump and AC. Why they are so expensive is really just price gouging because they aren't as common.
If you are in a home with forced air AC then installing a heatpump system couldn't be simpler and should be something you consider when updating your AC system. It's really just a matter of updating the compressor and maybe adding some smarts to avoid condensation. In fact, it's shocking to me that AC -> heatpump conversion kits haven't hit the market.
> So i'm slightly mystified that we basically don't hear anything about fitting drainwater heat recovery [1], in which the lukewarm drain water from your shower is used to pre-warm the incoming cold water. It's extremely simple, pretty cheap, simple to fit, and can recover ~50% of the waste heat, of something which is tens of percent of the energy consumption of a household.
Really interesting idea, but I assume you have to rip up the shower to accomplish this right? Also, I'm guessing clogged wastewater piping might be an issue right? That said, that'd be easily overcome by just running the lines side by side with maybe a simple copper connector for heat exchange.
And, you don't need to add insulation, but we did (to the crawlspace), costing about $2.5k
And, it's been running for about 3 months, and saved about ~$175/month in heating. wow. It'll pay for itself in about 7-8 years.
It may be that they're relatively new to your area, so the demand is outstripping supply of installers who have been doing this for 30+ years and as such are charging to that effect.
Definitely a cool idea but a leak or any maintenance might quickly undercut the cost savings
> Information obtained from the US Census Bureau’s Survey of Construction (SOC) and tabulated by NAHB, shows that the rising trend of single-story homes reversed in 2021. The share of single-story homes decreased in 2021 and the share of two or more stories homes started was greater than one story homes. This is in line with recent NAHB analysis of new single-family home size trends.
https://eyeonhousing.org/2022/07/share-of-two-or-more-storie...
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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
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
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.
I had a Moovair with three heads installed.
Is there two per indoor head?
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.
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.
Many new homes that are heat pump only will also require some sort of resistive heating as a backup.
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.
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?
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.
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.
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...)
I think Northern England climate is ideal for heat pumps -- it never gets too cold, never gets too hot.
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.
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.
I think the key thing here is that energy is 100% fungible unlike your examples. A kWH is a kWH.
I agree, what kind of hat is your house wearing?
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!
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.
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.
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.
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.
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.
> 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.
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.
It's definitely challenging to find trades who have both the knowledge and interest to innovate relative to standard HVAC installations in the area.
I doubt the architect puts such a miserly lens on the other projects they’re involved in.
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.
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.
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.
Curious if getting rid of those drafts may be unknowingly affecting your health in other areas.
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.
[1] https://www.ahridirectory.org
As a shopper, I’d want to see a nearby house’s figures as-installed by my prospective contractor.
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.
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
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.
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.
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.
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.
The best guide I could find is buried all the way down of the documentation https://docs.openenergymonitor.org/applications/heatpump.htm...
That's it.
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.
In general though, it's more the idealogy that gets me. It would be so easy to do a little more work to make things repairable, to use common parts, and ultimately create units that could last decades instead of lasting until an electric board has a short from dust or a pump predictably dies just outside of warranty, taking out an otherwise perfectly functional unit. It's just not viewed as the most profitable way, atleast not with how most people buy things today.
I think it could be profitable though, if you get enough people that can do the math and realize that over a lifetime it's cheaper than I think you could make that work. Additionally, it's not just about the cost over time but what happens when failures inevitably happen. Try having a repair done on any appliance today under warranty. First you have to go through the company and you get whoever they send and then you need their parts, if they are still available, which often they aren't. If the documentation on how to repair/maintain is opensource then you could potentially get anyone to fix it and if the components are COTS were possible then you aren't screwed when your 5 year old heat pump has an electrical failure because you can just but a new board (raspberry pi lets say) flash the software and install it.
I'm simplifying but I think you get the idea.
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.
The most egregious example of this I will highlight is electronics. Ask any manufacturer to provide a replacement board for an otherwise functional heat pump, air conditioner, etc. They likely won't have one. And even if they do, are you now going to hire someone to replace it? Do it yourself? If you aren't mechanically inclined its option one which can be hundreds of dollars and if its option two you will now be doing it likely with no or poor documentation spending how much of your time?
Heat pumps are no more sensitive to maintenance than air conditioners (besides the use of longer hoses for the refrigerant movement giving more opportunities to generate leaks). Or atleast their nature doesn't mean they inherently need to be (maybe that's the better way to put it). Compressors, fans, radiators, inverters, these are things that have been made for decades and if you walk into any commercial manufacturing space you'll find examples last for decades. That level of quality just isn't offered for homes.
You are absolutely correct that over-specifying heat pumps is also a big issue. That's kinda've a whole nother topic though that we could get into along with energy modeling, regualtions/practices, etc.
Factory supplied parts disappear fairly rapidly after products are end-of-life and labor to repair can be quite expensive.
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?
My natural gas cost is $0.82/CCF or $0.028/kWh. Electric is $0.161/kWh. That means a heat pump needs to be 575% efficient to break even on energy cost (assuming my furnace is 100% efficient, it's not, a lot of heat goes out the chimney).
People only get heat pumps here if they're carbon-conscious.
Newer heat pumps have gotten a lot better, and as a result a few people are starting to use them here. Even so most heat pumps are the more expensive type that rely on geothermal coils. We have extreme seasonal temperature changes that make older heat pumps impractical. For about two weeks each winter, our overnight lows are around -20F (-29C) and we often see wind chills around -40. Summer temperatures regularly reach 100F (38C).
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).
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).
My apartment in the UK was even weirder: It had something called a "Economy 10", with an electric heater (resistance?) in a concrete slab under the floors that would run at night, then release heat slowly throughout the day. (No A/C)
>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
IMO, the problem is that HVAC companies in the US overcharge so much for install/labor that homeowners are more inclined to replace them. They won't touch mini split brands that they don't install (and generally only install expensive brands)
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.
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).
Activism.