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.

How are heat pumps typically installed? Are they integrated into the radiator/hot water system? Or is some sort of forced air system setup installed?

I'd assume a mini split setup wouldn't be too uncommon. (Probably the cheapest route for most homes in the UK).

In the US the vast majority of homes and apartments are setup with forced air heating and cooling which really simplifies transition. I'd assume the UKs setup where everyone uses heated water to heat homes would make transition more expensive and costly.

Definitely a cool idea but a leak or any maintenance might quickly undercut the cost savings

Sustained cold spells are where you need an alternative heat source.

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

(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!)

(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!)

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]).

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).

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!)

Over here they're called hybrid heat pumps and are quite popular. (At least with those that offer to sell them.) They're used in improving existing gas powered solutions. The heat pump takes most (or usually all) of the heating, while the existing gas heater provides hot water and can add peak heat if needed.

I think the challenge is determining how much energy you save. I guess we could run the calculations and back out nat gas savings.

Managing the microcontrollers might be a bit of a pain though.

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

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.

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

I had a Moovair with three heads installed.

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

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.

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.

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...

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.

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.

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.

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...

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?

That's far too low to justify the huge sums involved in energy renovations.

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

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.

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.

German building standards contribute to the longevity of residential buildings.

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.

Better is always good

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 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.

Very handy for checking for drafts and cold spots, and also checking the fuse box and other electrical for hot spots.

The resolution is not amazing, 206x156, but it's enough for this type of work.

I have a friend who is happily using a flir one, with a resolution of 160x120 at his day job as an electrician and it is also enough for checking for draft, water leaks insufficient insulation, etc.

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.

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.

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.

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.

> 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.

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.

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.

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.

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

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

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.)

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.

[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

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.

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.

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.

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.

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.

No different this time round I imagine.

It's so infuriating - literally handing money to conmen

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.

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

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.

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.

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.

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.

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).

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)

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).

>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.

Activism.

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).

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.

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

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).

I recently paid 325 euros (about $350) for a unit and 200 euros (about $215) for installation. They are cheap Chinese units but the quality is good in terms of performance. This year they might be even cheaper.

Note that 25% of those prices are tax.

You can buy a single head mini split for under $800 and the tools to install cost under $200, which you can reuse.

If you pick a good location (room with an exterior wall), the install is trivial.

By law, houses in my neck of the woods are required to be well insulated, where the definition gets stricter every couple of years. Newly built houses have to be compliant. When renovating existing houses, efforts towards compliance have to be made up to a certain level. Every house that's sold or rented must advertise its energy consumption expressed in kW/m², and you can be damned sure that high energy loss results in severe impact on sales price.

Any kind of heater obviously has less work to do when heat loss is minimized by good insulation. Good options have been available for literally decades for most types of buildings.

The roof is typically the easiest, with many options. E.g. on the inside between the rafters. Or you can remove the tiles, insulate on the outside, add framing and retile. My roofer simply tore out the ancient roofing, slapped on some insulation, and finished things with EPDM. Easy peasy.

Floors can be tricky depending on the house and how much effort you're willing to put in. Easy if you have a crawlspace or basement, not so easy if not. I tore up and dug out the floors in my 100+ year old house and added 10cm of PIR insulation. This was not much fun, but after a hundred years the floor looked like shit anyway.

Walls have lots of options. Cavity walls can be filled with insulation by drilling a couple of holes and blowing it in. I insulated my brick walls on the outside, 12cm of XPS, with a layer of reinforcement, and finished with silicone plaster rendering.

Don't forget about the windows. Old windows are very leaky. Not just the glazing (double or triple for the win), but the framing is equally important. Also great for keeping out noise.

And then there's ventilation. I installed a forced air ventilation system with heat and moisture recovery. This had a bigger impact than expected, the indoor air is much nicer, and I don't lose any heat by having to open windows in the winter.

In all cases, of course, moisture has to be taken into account. You may or may not need a moisture barrier, some parts may have to be breathable, etc.

Over here, subsidies are available for most of these improvements, and our energy prices are high enough to make it worth the effort.

I pay under 200eur/year (not a typo) for heating, and most of that goes towards hot showers.

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!)

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.