7 ms·

Heat pumps, heat pumps, heat pumps

26 points by jseliger 3y ago

seydor 3y ago
Aren't heat pumps the same as air conditioning? I have one
- easytiger 3y ago
  > Aren't heat pumps the same as air conditioning? I have one not even remotely
  - seydor 3y ago
    I ma fairly sure that in europe A/C and heat pumps are the same (cooling/heating)
    - easytiger 3y ago
      Then you are incorrect
  - brianwawok 3y ago
    That’s a stretch.
    - easytiger 3y ago
      Do explain
  - SkyPuncher 3y ago
    They’re actually nearly identical in concept. An air conditioner is actually just a one-way heat pump. The major difference is heat pumps can run in reverse.
  - OGWhales 3y ago
    Actually an AC unit is a heat pump, just a one directional one that moves the heat outside.
    - throwaway173738 3y ago
      It depends. Window or floor units that are portable are not usually heat pumps. They use a different cycle with the refrigerant. Ductless splits and central air are often heat pumps.
      - empyrrhicist 3y ago
        How so? Anything using vapor compression refrigeration should technically qualify as a heat pump. They may not move the heat as far, but that shouldn't matter. A swamp cooler isn't a heat pump, but the units you describe would seem to me to obviously qualify.
      - amluto 3y ago
        You can buy portable window heat pumps from several companies. They’ve been around for a while.
        vel0city 3y ago
        Sure, there might be some in some markets, but when I go to the store around here practically none of them are heat pumps. They're rare to find shopping around for some reason. Like, look at this list. How many will heat? Probably none. https://www.lowes.com/pl/Window-air-conditioners-Room-air-conditioners-Air-conditioners-fans-Heating-cooling/3788568798 https://www.lowes.com/pl/Window-air-conditioners-Room-air-co... I can walk into a dozen stores selling window AC units around me with hundreds in stock ready to go today. If I want one with heat near me, I'll have to custom order online. Thus, the vast majority of window AC units you'll encounter in most of the US are cooling-only unless the person knew they could order one which does heat from someplace else online.
        amluto 3y ago
- ZeroGravitas 3y ago
  > When it’s cooling your house, it’s just a normal AC. But did you ever think “When it’s cold outside, why can’t we just turn the AC around and air-condition the outside, so it heats up inside?” Well, it turns out you can! And that is how a heat pump works. It just moves heat from the outside of your house to the inside, just by turning the air conditioning in reverse.
  - seydor 3y ago
    That's what most air-conditioning does in europe, it is also used for heating
    - ZeroGravitas 3y ago
      Probably location dependant but numerically I'd guess most ACs that Europeans have interacted with are in cars, which only very recently started using heat pumps for heat in the EV era.
      - dukeyukey 3y ago
        That dpends where you are in EUrope. Lots of housing have AC in the Mediterranean countries, and even in the famously AC-deficient UK pretty much every office building and supermarket will have AC.
    - vel0city 3y ago
      I wouldn't say most air-conditioning in Europe includes heat pump heating, in fact for most of Europe I'd say its not super common. Germany is in Europe. Only 4% of residential heating is from electrical sources, which is both heat pumps and resistive heat. 51% of household heating is from natural gas, 20% is from heating oil, and 18% is from district heating. https://www.statista.com/statistics/1189752/household-heating-sources-germany/ https://www.statista.com/statistics/1189752/household-heatin... Here's iea's residential heating sources in 2020. Italy (also in Europe) sourced 60% of its energy for residential heating from gas. Hover over electricity and see how low of a percentage it is in most countries. https://www.iea.org/data-and-statistics/charts/proportion-of-residential-heating-energy-consumption-by-fuel-source-in-selected-countries-2020 https://www.iea.org/data-and-statistics/charts/proportion-of...
- SkyPuncher 3y ago
  They’re the same core concept. There are generally two major differences: * a heat pump has a switch valve for coolant. This allows it to move heat in either direction. * while not strictly necessary, heat pumps typically have a variable rate compressor. They scale to match load. Some heat pumps will also have a supplemental electric heat element when conditions are extremely cold.
- semiquaver 3y ago
  This feels like a US vs rest-of-the-world thing. In the US, “central” air conditioning is usually one-way and paired with a furnace for the winter. The main alternative is window ac-only units which are removed in the winter. Mini-split heat pump units that heat and cool are everywhere in Asia and parts of Europe but are still relatively uncommon in most of the US. I installed one last year and had to shop around for an installer, several of which tried to talk me out of it. If this is what you think of as “air conditioning” then you’re right. Most Americans would think of a central air system that cannot heat.
  - local_crmdgeon 3y ago
    Minisplits are becoming very common in the older cities - NYC, Boston - where they're much easier to retrofit into plaster-and-lathe walls.
  - eep_social 3y ago
    In regions like the Southwestern US, where furnaces are not needed, AC units are heat pumps. The US is large enough to defy most generalizations.
- throwbadubadu 3y ago
  Yep, most people have "heat pumps" already .. in their car or refrigerator ;)
mytailorisrich 3y ago
One of the issues with heat pumps is that there are very bulky and may require big installation work.
- dkqmduems 3y ago
  The alternative being what?
  - mytailorisrich 3y ago
    No heat pump? IMHO, the main reason heat pumps are pushed is that most countries are having big issues with their electricity production and grids. Indeed, the move away from ICE cars and gas at home means electricity production is struggling. Cynically: "Look we don't need to invest we can just tell people to install heat pumps". Here in the UK for many properties heat pumps are either very expensive to install or they destroy the small garden/patio people have, or both so I can see people trying their best to avoid them, quite reasonably so because there are not well suited.
    - notyourwork 3y ago
      I don’t follow your logic at all. Sorry.
    - OGWhales 3y ago
      Huh? The main reason heat pumps are being pushed is because they are extremely efficient, not as some kind of sacrifice that we are doing to protect the grid. There is no better option if we are moving away from gas at home. The only competitive alternative is gas powered heating. However, I believe it’s more energy efficient to use natural gas for electricity generation and use heat pumps for heating rather than piping gas to people’s homes and burning it there. The exception is when it’s so cold that heat pumps do not perform well (although modern heat pumps can work in very cold situations)
      - cesaref 3y ago
ZeroGravitas 3y ago
One of the most amazing triumphs/failures of capitalism, is the ability to fend off competitors with even a mildly long payback period for decades. It boggles my mind that modern democracies like Germany or the UK could have ignored heat pumps for so long.
- yodelshady 3y ago
  Because it isn't mildly long. It's either very long or infinite, anywhere where gas is ~ 1/3 the cost of electricity per kWh. COP of 3 at a 3:1 price ratio for electricity to gas = 1. Which itself makes sense if you use gas as the RELIABLE source of kWh. You need to burn ~ 3kWh of primary energy in gas to deliver 1 kWh to the household, so 3:1 makes sense, and the RELIABLE source of kWh is the price setter because a failure of the grid is literally an existential crisis, something the "agile" private sector companies aren't liable for. An auxiliary annoyance in the UK is that reversible pumps aren't renewable for government grants. This is ostensibly to discourage aircon, but rather silly, since there are few easier green power problems today than "satisfy a demand that is almost perfectly correlated with high insolation". FYI as a type the largest suppliers are gas, solar, then nuclear - of which nearly half is being pulled from France, an amount that for some reason isn't always counted by some people.
  - yathern 3y ago
    > you need to burn ~3kWh of primary energy in gas to deliver 1 kWh to the household Is that so? I thought electric generation from natural gas was at least 80% efficient - and transmission losses maybe can pull that as far down as 66% - but not down to 1/3.
    - voisin 3y ago
      I think they are referring to the COP of a heat pump as at least 3, whereas natural gas appliances by definition must be below 1.
  - ZeroGravitas 3y ago
    In many EU countries that cost difference is a policy failure: > Italy, Spain, the United Kingdom, Belgium and Germany. All five countries overtax electricity — in three cases by more than 200% — and undertax oil and fossil gas while not taxing wood use at all. Only in Italy is the tax rate on heating oil close to the value of the environmental costs caused by its use. https://www.raponline.org/knowledge-center/aligning-heating-energy-taxes-levies-europe-climate-goals/ https://www.raponline.org/knowledge-center/aligning-heating-... But going from first principles Renewable Energy Without the Hot Air could run the numbers back when it was written in 2008 and show this was a good move: https://www.withouthotair.com/c21/page_151.shtml https://www.withouthotair.com/c21/page_151.shtml > Let me spell this out. Heat pumps are superior in efficiency to condensing boilers, even if the heat pumps are powered by electricity from a power station burning natural gas.
euroderf 3y ago
The first part of this article is a good intro to how they work. But still, one flaw. I'm guessing that a lot of people are simply not aware that compressing a gas will heat it and decompressing it will cool it - at least not to any significant degree. So (imho) please talk about how the operation of an A/C makes this fact obvious - make an appeal to everyday experience. And THEN talk about how putting it in reverse makes a heater, even when it's really damned cold outdoors.
- yathern 3y ago
  You probably already know this, but for anyone else reading - it's more than just compressing and decompressing - it's changing phase between liquid and solid! It takes a lot of extra energy to go from a liquid to a gas - think about how when boiling water, it doesn't all immediately turn into steam when it hits 100 degrees. It takes a long time to boil it down to nothing, even on a really hot stove. That's because switching from liquid to gas takes more energy than just getting hotter. The refrigerants used in ACs and heat pumps take advantage of this behavior to maximize how much heat they can move - much more than if they stayed as a gas
  - euroderf 3y ago
    Good point. I kinda skipped over the phase change part of the story. This too can be used explain the heat pump concept better. Freezing or boiling water takes time because it takes energy.
nlh 3y ago
Pardon me for being out of the loop (I am not yet a homeowner and things like this are beyond me for the moment): Is there a reason heat pumps are now more relevant? Has there been a technological innovation here? Is this new technology? (I'm asking this genuinely - not with snark). I feel like I've read/heard about heat pumps a lot more recently and I'm wondering why. Many thanks in advance!
- hef19898 3y ago
  Heat pumps exist for quite a while. The reason ypu hear about them is climate change, all alternatives, from gas to oil, burn fussil fuels. That discussion was pushed by the war in Ukraine and, lately, a highly populized, and polarized, debate in Germany. The only alternative being equally good for the climate is using excess heat from industrial plants, e.g. those burning garbage. Up to know, at least in Germany, gas was just unbeatably cheap for heating houses. That's gonna change.
- dml2135 3y ago
  Two reasons. One, yes they have gotten more efficient, and depending on your local climate, are now possibly the most efficient method for heating your home. Two, the switch to renewable energy is resulting in a push for the “electrification of everything”. Getting home appliances that previously burned fossil fuels onto the electric grid enables emissions-free methods of power generation to be used in the future, even if they are not in use yet. And even with fossil-fuel burning power plants, they have an economy of scale much greater than the furnace in your home. So using electricity generated at a fossil-fuel burning power plant to power your heat pump will still result in less emissions than burning that fuel for heat directly in your home.
- Gasp0de 3y ago
  Fossil fuels should not be used to create heat anymore due to climate change. People are becoming more aware of that currently (especially in Europe) which is why heatpumps are a hot topic.
  - hef19898 3y ago
dsign 3y ago
Here is how I try to get people enthusiastic about heat pumps: we need some really big heat pumps for some really big space habitats.
jibe 3y ago
And in some states in New England and the Pacific Northwest, there are a substantial number of households that still don’t even have AC, which reduces the savings from heat pumps. The percentage of households without A/C in California is even higher than Oregon. 28% vs 24%. The states with the highest percentage are Alaska at 93%, Washington at 47%, and Hawaii at 43%. Data from: https://www.eia.gov/consumption/residential/data/2020/state/pdf/State%20Air%20Conditioning.pdf https://www.eia.gov/consumption/residential/data/2020/state/...
ellisv 3y ago
> Heat pumps heat your house much more cheaply than other types of heating, since they’re incredibly energy-efficient. So you can save money. Yes, but no. Heat pumps are more efficient but generally natural gas prices are much lower than electricity prices for consumers. I should be able to save money because my utility should incentivize me to be more energy efficient and help offset the cost but they don't.
- Gasp0de 3y ago
  It strongly depends on the country you live in. But generally we can hope that gas is going to be more expensive than electricity in the future.
  - xela79 3y ago
    no. We can hope that electricity becomes a lot cheaper than gas. a distinct difference. your phrase would mean that they just make gas more expensive, and overall heating costs just rise we should have had an abundance of electricity by now, but nuclear disasters in US, EU and JPN have really slowed that upwards trend of power source to a crawl
    - Gasp0de 3y ago
      Nuclear is way more expensive than wind or solar power so nuclear will not play any part in reducing electricity prices.
      - the_third_wave 3y ago
        Nuclear has the large advantage of being available at those cold quiet winter nights when the temperature drops below what is considered pleasant and you'd like to warm your home. Solar does not work come wintertime here in the north, wind sometimes works but often does not. If your country has the geography to allow for hydroelectric plants those are a good option which can even be used to store excess power from solar and wind, otherwise nuclear is one of the few dependable sources which do not rely on fossil fuels. Geothermal is another but that is even more geographically limited than hydroelectric.
jokoon 3y ago
I really wish I could buy a miniature heat pump to blow cold air on my body or face instead of cooling my entire room. Obviously there would be 2 units, one inside and one outside, but mobile AC units are way too big, consume too much power, and suck hot air from outside which is quite inefficient (the physics are simple, a mobile AC units ejects hot air outside, so air must enter the room somehow). I hope it would be possible to have a small, simpler heat pump that use something else than a refrigerant gas, maybe co2. I could buy the cheapest fridge and make one, but I can't extend the range of the gaz pipe.
- Gasp0de 3y ago
  It doesn't necessarily eject hot air outside, right? It just "ejects" heat outside. It could easily have two tubes or something, sucking in warm air from the outside, heating it up, and ejecting it outside again. However, since you have to create a (temporary) opening to put part of the mobile ac outside, warm air will still get in. You could just use a fan to blow air over water onto your body. The evaporation will cool it down a little.
  - jokoon 3y ago
    The cheap one units AC on wheels do eject hot air outside. At least in europe we don't have the window AC units, we have either split or single unit on wheels.
- sn9 3y ago
  They're not cheap, but they exist. https://www.coolmitt.com/ https://www.coolmitt.com/
Gasp0de 3y ago
The one thing that is missing from this article is that heat pumps can only create a certain temperature difference (while remaining efficient). In Europe, most houses are heated by pumping hot water through radiators (as opposed to blowing hot air around). Heatpumps can typically only heat that water up to 30 to 40 degrees Celsius while remaining efficient, which is not enough to heat the old, badly insulated houses in Europe. They need to renovate houses first, insulate them and replace the radiators.
- ZeroGravitas 3y ago
  For Condensing boilers, the temperature of the water coming back from the radiators needs to be 45C in order to hit the advertised efficiency and eponymous "condensing", this is why their real measured efficiency is more like 75-85% than 96+% Same fix, larger, double vaned radiators and better insulation which is why some people are pleasantly surprised they don't need to switch radiators when moving from a modern condensing boiler setup.
xg15 3y ago
> Maybe a heat pump is just too boring and simple to have a culture war about. As a German, I can confidently reject that hypothesis...
ortusdux 3y ago
I highly recommend heat pump water heaters if they fit your use case. Mine cost $650 after rebates and dropped my annual electrical usage by ~$400. They have some quirks. There is a condensate line that needs to constantly drain. Also, they pull heat from the air, so it is usually best to have them outside of conditioned spaces. You can also duct them however you like. All that being said, I installed mine in under a day.
- voisin 3y ago
  I just ordered a Rheem Proterra and am excited to give it a try!
dist-epoch 3y ago
> they take up less space than a normal heater plus normal AC. Don't you still need a normal heater for hot water?
- Gasp0de 3y ago
  Why shouldn't you use the heat pump to heat water?
  - voisin 3y ago
    Do they make heat pumps that do both air and water in one unit? I haven’t seen this.
    - Gasp0de 3y ago
      In Europe, houses are heated using warm water so its the same. Also, many heat pumps store heat in a warm water buffer. You can use a heat exchanger to heat water with it. The american way of heating the house by blowing hot air around isn't the most efficient as air doesn't transport energy very well.
dist-epoch 3y ago
> Our £25,000 heat pumps left us out of pocket. Brits who signed up for boiler upgrade scheme are left facing £5,000 energy bills, wake up to cold homes and have to use blankets to keep warm https://www.dailymail.co.uk/news/article-11972635/Britons-complain-problems-heat-pumps-amid-soaring-energy-bills.html https://www.dailymail.co.uk/news/article-11972635/Britons-co...
- Gasp0de 3y ago
  Whats that supposed to tell us? That someone didn't understand heat pumps, put a wrongly sized heatpump into a wrongly equipped house and now the owners are complaining?
Simulacra 3y ago
Related, we recently put in a hot water heater with a heat pump. It blows cold air exhaust, so it keeps our basement nice and cool. It has worked well and reduced our power bill slightly.
dogleash 3y ago
Nuclear, nuclear, nuclear. You can't fix global energy problems by raising everyone's HVAC coefficient of power to 4.
2-718-281-828 3y ago
any idea about what secondary technology to invest in in anticipation of heat pumps catching on?
- voisin 3y ago
  Installer networks with installers that understand the technology rather than try to talk customers out of it.
jillesvangurp 3y ago
Michael Liebherr, who runs the cleaning up podcast series and is a British Conservative politician as well as the founder of the Bloomberg Clean Energy fund, has been calling up electrified heating and industrial heating as the next trillion dollar investment opportunity. The solution there is mainly going to be switching from burning stuff to using heat pumps and other solutions. The reason the opportunity is so large is that there is a huge potential for cost savings there. Heatpumps can deliver 3x or more energy back for every unit of energy you put in. Contrary to the popular belief there are almost no industrial heat applications that can't be electrified. The majority is rather easy and involves applications that require heat in the lower hundreds of degrees celsius. Easy. Heatpumps can do that. All you need is a good source of temperature gradient and electricity. You can go much higher than that with resistive heating, plasma heating, inductive heating, etc. It's just a matter of applying enough power to these things. You eliminate a lot of emissions, supply issues and other logistics by doing so. That's where the cost savings are going to be.
evronm 3y ago
Am I the only one having DNS issues with this site? For some reason, no matter which DNS server I query, it resolves to my router, yet it seems most everyone reaches it without issue.
voisin 3y ago
The biggest problem I see, as someone who has tried to get a heat pump installed in both residential and commercial settings, is that the trades are very, very slow to change. They have, by and large, built their careers on burning natural gas and are not willing to entertain the idea that it isn’t necessary, particularly where the new product requires less maintenance which is their bread and butter. It will change, but oh so slowly.

26 points by jseliger 3y ago

seydor 3y ago

Aren't heat pumps the same as air conditioning? I have one

easytiger 3y ago
> Aren't heat pumps the same as air conditioning? I have one not even remotely
- seydor 3y ago
  I ma fairly sure that in europe A/C and heat pumps are the same (cooling/heating)
  - easytiger 3y ago
    Then you are incorrect
- brianwawok 3y ago
  That’s a stretch.
  - easytiger 3y ago
    Do explain
- SkyPuncher 3y ago
  They’re actually nearly identical in concept. An air conditioner is actually just a one-way heat pump. The major difference is heat pumps can run in reverse.
- OGWhales 3y ago
  Actually an AC unit is a heat pump, just a one directional one that moves the heat outside.
  - throwaway173738 3y ago
    It depends. Window or floor units that are portable are not usually heat pumps. They use a different cycle with the refrigerant. Ductless splits and central air are often heat pumps.
    - empyrrhicist 3y ago
      How so? Anything using vapor compression refrigeration should technically qualify as a heat pump. They may not move the heat as far, but that shouldn't matter. A swamp cooler isn't a heat pump, but the units you describe would seem to me to obviously qualify.
    - amluto 3y ago
      You can buy portable window heat pumps from several companies. They’ve been around for a while.
      - vel0city 3y ago
        Sure, there might be some in some markets, but when I go to the store around here practically none of them are heat pumps. They're rare to find shopping around for some reason. Like, look at this list. How many will heat? Probably none. https://www.lowes.com/pl/Window-air-conditioners-Room-air-conditioners-Air-conditioners-fans-Heating-cooling/3788568798 https://www.lowes.com/pl/Window-air-conditioners-Room-air-co... I can walk into a dozen stores selling window AC units around me with hundreds in stock ready to go today. If I want one with heat near me, I'll have to custom order online. Thus, the vast majority of window AC units you'll encounter in most of the US are cooling-only unless the person knew they could order one which does heat from someplace else online.
        amluto 3y ago
ZeroGravitas 3y ago
> When it’s cooling your house, it’s just a normal AC. But did you ever think “When it’s cold outside, why can’t we just turn the AC around and air-condition the outside, so it heats up inside?” Well, it turns out you can! And that is how a heat pump works. It just moves heat from the outside of your house to the inside, just by turning the air conditioning in reverse.
- seydor 3y ago
  That's what most air-conditioning does in europe, it is also used for heating
  - ZeroGravitas 3y ago
    Probably location dependant but numerically I'd guess most ACs that Europeans have interacted with are in cars, which only very recently started using heat pumps for heat in the EV era.
    - dukeyukey 3y ago
      That dpends where you are in EUrope. Lots of housing have AC in the Mediterranean countries, and even in the famously AC-deficient UK pretty much every office building and supermarket will have AC.
  - vel0city 3y ago
    I wouldn't say most air-conditioning in Europe includes heat pump heating, in fact for most of Europe I'd say its not super common. Germany is in Europe. Only 4% of residential heating is from electrical sources, which is both heat pumps and resistive heat. 51% of household heating is from natural gas, 20% is from heating oil, and 18% is from district heating. https://www.statista.com/statistics/1189752/household-heating-sources-germany/ https://www.statista.com/statistics/1189752/household-heatin... Here's iea's residential heating sources in 2020. Italy (also in Europe) sourced 60% of its energy for residential heating from gas. Hover over electricity and see how low of a percentage it is in most countries. https://www.iea.org/data-and-statistics/charts/proportion-of-residential-heating-energy-consumption-by-fuel-source-in-selected-countries-2020 https://www.iea.org/data-and-statistics/charts/proportion-of...
SkyPuncher 3y ago
They’re the same core concept. There are generally two major differences: * a heat pump has a switch valve for coolant. This allows it to move heat in either direction. * while not strictly necessary, heat pumps typically have a variable rate compressor. They scale to match load. Some heat pumps will also have a supplemental electric heat element when conditions are extremely cold.
semiquaver 3y ago
This feels like a US vs rest-of-the-world thing. In the US, “central” air conditioning is usually one-way and paired with a furnace for the winter. The main alternative is window ac-only units which are removed in the winter. Mini-split heat pump units that heat and cool are everywhere in Asia and parts of Europe but are still relatively uncommon in most of the US. I installed one last year and had to shop around for an installer, several of which tried to talk me out of it. If this is what you think of as “air conditioning” then you’re right. Most Americans would think of a central air system that cannot heat.
- local_crmdgeon 3y ago
  Minisplits are becoming very common in the older cities - NYC, Boston - where they're much easier to retrofit into plaster-and-lathe walls.
- eep_social 3y ago
  In regions like the Southwestern US, where furnaces are not needed, AC units are heat pumps. The US is large enough to defy most generalizations.
throwbadubadu 3y ago
Yep, most people have "heat pumps" already .. in their car or refrigerator ;)

mytailorisrich 3y ago

One of the issues with heat pumps is that there are very bulky and may require big installation work.

dkqmduems 3y ago
The alternative being what?
- mytailorisrich 3y ago
  No heat pump? IMHO, the main reason heat pumps are pushed is that most countries are having big issues with their electricity production and grids. Indeed, the move away from ICE cars and gas at home means electricity production is struggling. Cynically: "Look we don't need to invest we can just tell people to install heat pumps". Here in the UK for many properties heat pumps are either very expensive to install or they destroy the small garden/patio people have, or both so I can see people trying their best to avoid them, quite reasonably so because there are not well suited.
  - notyourwork 3y ago
    I don’t follow your logic at all. Sorry.
  - OGWhales 3y ago
    Huh? The main reason heat pumps are being pushed is because they are extremely efficient, not as some kind of sacrifice that we are doing to protect the grid. There is no better option if we are moving away from gas at home. The only competitive alternative is gas powered heating. However, I believe it’s more energy efficient to use natural gas for electricity generation and use heat pumps for heating rather than piping gas to people’s homes and burning it there. The exception is when it’s so cold that heat pumps do not perform well (although modern heat pumps can work in very cold situations)
    - cesaref 3y ago

ZeroGravitas 3y ago

One of the most amazing triumphs/failures of capitalism, is the ability to fend off competitors with even a mildly long payback period for decades. It boggles my mind that modern democracies like Germany or the UK could have ignored heat pumps for so long.

yodelshady 3y ago
Because it isn't mildly long. It's either very long or infinite, anywhere where gas is ~ 1/3 the cost of electricity per kWh. COP of 3 at a 3:1 price ratio for electricity to gas = 1. Which itself makes sense if you use gas as the RELIABLE source of kWh. You need to burn ~ 3kWh of primary energy in gas to deliver 1 kWh to the household, so 3:1 makes sense, and the RELIABLE source of kWh is the price setter because a failure of the grid is literally an existential crisis, something the "agile" private sector companies aren't liable for. An auxiliary annoyance in the UK is that reversible pumps aren't renewable for government grants. This is ostensibly to discourage aircon, but rather silly, since there are few easier green power problems today than "satisfy a demand that is almost perfectly correlated with high insolation". FYI as a type the largest suppliers are gas, solar, then nuclear - of which nearly half is being pulled from France, an amount that for some reason isn't always counted by some people.
- yathern 3y ago
  > you need to burn ~3kWh of primary energy in gas to deliver 1 kWh to the household Is that so? I thought electric generation from natural gas was at least 80% efficient - and transmission losses maybe can pull that as far down as 66% - but not down to 1/3.
  - voisin 3y ago
    I think they are referring to the COP of a heat pump as at least 3, whereas natural gas appliances by definition must be below 1.
- ZeroGravitas 3y ago
  In many EU countries that cost difference is a policy failure: > Italy, Spain, the United Kingdom, Belgium and Germany. All five countries overtax electricity — in three cases by more than 200% — and undertax oil and fossil gas while not taxing wood use at all. Only in Italy is the tax rate on heating oil close to the value of the environmental costs caused by its use. https://www.raponline.org/knowledge-center/aligning-heating-energy-taxes-levies-europe-climate-goals/ https://www.raponline.org/knowledge-center/aligning-heating-... But going from first principles Renewable Energy Without the Hot Air could run the numbers back when it was written in 2008 and show this was a good move: https://www.withouthotair.com/c21/page_151.shtml https://www.withouthotair.com/c21/page_151.shtml > Let me spell this out. Heat pumps are superior in efficiency to condensing boilers, even if the heat pumps are powered by electricity from a power station burning natural gas.

euroderf 3y ago

The first part of this article is a good intro to how they work. But still, one flaw. I'm guessing that a lot of people are simply not aware that compressing a gas will heat it and decompressing it will cool it - at least not to any significant degree. So (imho) please talk about how the operation of an A/C makes this fact obvious - make an appeal to everyday experience. And THEN talk about how putting it in reverse makes a heater, even when it's really damned cold outdoors.

yathern 3y ago
You probably already know this, but for anyone else reading - it's more than just compressing and decompressing - it's changing phase between liquid and solid! It takes a lot of extra energy to go from a liquid to a gas - think about how when boiling water, it doesn't all immediately turn into steam when it hits 100 degrees. It takes a long time to boil it down to nothing, even on a really hot stove. That's because switching from liquid to gas takes more energy than just getting hotter. The refrigerants used in ACs and heat pumps take advantage of this behavior to maximize how much heat they can move - much more than if they stayed as a gas
- euroderf 3y ago
  Good point. I kinda skipped over the phase change part of the story. This too can be used explain the heat pump concept better. Freezing or boiling water takes time because it takes energy.

nlh 3y ago

Pardon me for being out of the loop (I am not yet a homeowner and things like this are beyond me for the moment): Is there a reason heat pumps are now more relevant? Has there been a technological innovation here? Is this new technology? (I'm asking this genuinely - not with snark). I feel like I've read/heard about heat pumps a lot more recently and I'm wondering why. Many thanks in advance!

hef19898 3y ago
Heat pumps exist for quite a while. The reason ypu hear about them is climate change, all alternatives, from gas to oil, burn fussil fuels. That discussion was pushed by the war in Ukraine and, lately, a highly populized, and polarized, debate in Germany. The only alternative being equally good for the climate is using excess heat from industrial plants, e.g. those burning garbage. Up to know, at least in Germany, gas was just unbeatably cheap for heating houses. That's gonna change.
dml2135 3y ago
Two reasons. One, yes they have gotten more efficient, and depending on your local climate, are now possibly the most efficient method for heating your home. Two, the switch to renewable energy is resulting in a push for the “electrification of everything”. Getting home appliances that previously burned fossil fuels onto the electric grid enables emissions-free methods of power generation to be used in the future, even if they are not in use yet. And even with fossil-fuel burning power plants, they have an economy of scale much greater than the furnace in your home. So using electricity generated at a fossil-fuel burning power plant to power your heat pump will still result in less emissions than burning that fuel for heat directly in your home.
Gasp0de 3y ago
Fossil fuels should not be used to create heat anymore due to climate change. People are becoming more aware of that currently (especially in Europe) which is why heatpumps are a hot topic.
- hef19898 3y ago

dsign 3y ago

Here is how I try to get people enthusiastic about heat pumps: we need some really big heat pumps for some really big space habitats.

jibe 3y ago

And in some states in New England and the Pacific Northwest, there are a substantial number of households that still don’t even have AC, which reduces the savings from heat pumps. The percentage of households without A/C in California is even higher than Oregon. 28% vs 24%. The states with the highest percentage are Alaska at 93%, Washington at 47%, and Hawaii at 43%. Data from: https://www.eia.gov/consumption/residential/data/2020/state/pdf/State%20Air%20Conditioning.pdf https://www.eia.gov/consumption/residential/data/2020/state/...

ellisv 3y ago

> Heat pumps heat your house much more cheaply than other types of heating, since they’re incredibly energy-efficient. So you can save money. Yes, but no. Heat pumps are more efficient but generally natural gas prices are much lower than electricity prices for consumers. I should be able to save money because my utility should incentivize me to be more energy efficient and help offset the cost but they don't.

Gasp0de 3y ago
It strongly depends on the country you live in. But generally we can hope that gas is going to be more expensive than electricity in the future.
- xela79 3y ago
  no. We can hope that electricity becomes a lot cheaper than gas. a distinct difference. your phrase would mean that they just make gas more expensive, and overall heating costs just rise we should have had an abundance of electricity by now, but nuclear disasters in US, EU and JPN have really slowed that upwards trend of power source to a crawl
  - Gasp0de 3y ago
    Nuclear is way more expensive than wind or solar power so nuclear will not play any part in reducing electricity prices.
    - the_third_wave 3y ago
      Nuclear has the large advantage of being available at those cold quiet winter nights when the temperature drops below what is considered pleasant and you'd like to warm your home. Solar does not work come wintertime here in the north, wind sometimes works but often does not. If your country has the geography to allow for hydroelectric plants those are a good option which can even be used to store excess power from solar and wind, otherwise nuclear is one of the few dependable sources which do not rely on fossil fuels. Geothermal is another but that is even more geographically limited than hydroelectric.

jokoon 3y ago

I really wish I could buy a miniature heat pump to blow cold air on my body or face instead of cooling my entire room. Obviously there would be 2 units, one inside and one outside, but mobile AC units are way too big, consume too much power, and suck hot air from outside which is quite inefficient (the physics are simple, a mobile AC units ejects hot air outside, so air must enter the room somehow). I hope it would be possible to have a small, simpler heat pump that use something else than a refrigerant gas, maybe co2. I could buy the cheapest fridge and make one, but I can't extend the range of the gaz pipe.

Gasp0de 3y ago
It doesn't necessarily eject hot air outside, right? It just "ejects" heat outside. It could easily have two tubes or something, sucking in warm air from the outside, heating it up, and ejecting it outside again. However, since you have to create a (temporary) opening to put part of the mobile ac outside, warm air will still get in. You could just use a fan to blow air over water onto your body. The evaporation will cool it down a little.
- jokoon 3y ago
  The cheap one units AC on wheels do eject hot air outside. At least in europe we don't have the window AC units, we have either split or single unit on wheels.
sn9 3y ago
They're not cheap, but they exist. https://www.coolmitt.com/ https://www.coolmitt.com/

Gasp0de 3y ago

The one thing that is missing from this article is that heat pumps can only create a certain temperature difference (while remaining efficient). In Europe, most houses are heated by pumping hot water through radiators (as opposed to blowing hot air around). Heatpumps can typically only heat that water up to 30 to 40 degrees Celsius while remaining efficient, which is not enough to heat the old, badly insulated houses in Europe. They need to renovate houses first, insulate them and replace the radiators.

ZeroGravitas 3y ago
For Condensing boilers, the temperature of the water coming back from the radiators needs to be 45C in order to hit the advertised efficiency and eponymous "condensing", this is why their real measured efficiency is more like 75-85% than 96+% Same fix, larger, double vaned radiators and better insulation which is why some people are pleasantly surprised they don't need to switch radiators when moving from a modern condensing boiler setup.

xg15 3y ago

> Maybe a heat pump is just too boring and simple to have a culture war about. As a German, I can confidently reject that hypothesis...

ortusdux 3y ago

I highly recommend heat pump water heaters if they fit your use case. Mine cost $650 after rebates and dropped my annual electrical usage by ~$400. They have some quirks. There is a condensate line that needs to constantly drain. Also, they pull heat from the air, so it is usually best to have them outside of conditioned spaces. You can also duct them however you like. All that being said, I installed mine in under a day.

voisin 3y ago
I just ordered a Rheem Proterra and am excited to give it a try!

dist-epoch 3y ago

> they take up less space than a normal heater plus normal AC. Don't you still need a normal heater for hot water?

Gasp0de 3y ago
Why shouldn't you use the heat pump to heat water?
- voisin 3y ago
  Do they make heat pumps that do both air and water in one unit? I haven’t seen this.
  - Gasp0de 3y ago
    In Europe, houses are heated using warm water so its the same. Also, many heat pumps store heat in a warm water buffer. You can use a heat exchanger to heat water with it. The american way of heating the house by blowing hot air around isn't the most efficient as air doesn't transport energy very well.

dist-epoch 3y ago

> Our £25,000 heat pumps left us out of pocket. Brits who signed up for boiler upgrade scheme are left facing £5,000 energy bills, wake up to cold homes and have to use blankets to keep warm https://www.dailymail.co.uk/news/article-11972635/Britons-complain-problems-heat-pumps-amid-soaring-energy-bills.html https://www.dailymail.co.uk/news/article-11972635/Britons-co...

Gasp0de 3y ago
Whats that supposed to tell us? That someone didn't understand heat pumps, put a wrongly sized heatpump into a wrongly equipped house and now the owners are complaining?

Simulacra 3y ago

Related, we recently put in a hot water heater with a heat pump. It blows cold air exhaust, so it keeps our basement nice and cool. It has worked well and reduced our power bill slightly.

dogleash 3y ago

Nuclear, nuclear, nuclear. You can't fix global energy problems by raising everyone's HVAC coefficient of power to 4.

2-718-281-828 3y ago

any idea about what secondary technology to invest in in anticipation of heat pumps catching on?

voisin 3y ago
Installer networks with installers that understand the technology rather than try to talk customers out of it.

jillesvangurp 3y ago

Michael Liebherr, who runs the cleaning up podcast series and is a British Conservative politician as well as the founder of the Bloomberg Clean Energy fund, has been calling up electrified heating and industrial heating as the next trillion dollar investment opportunity. The solution there is mainly going to be switching from burning stuff to using heat pumps and other solutions. The reason the opportunity is so large is that there is a huge potential for cost savings there. Heatpumps can deliver 3x or more energy back for every unit of energy you put in. Contrary to the popular belief there are almost no industrial heat applications that can't be electrified. The majority is rather easy and involves applications that require heat in the lower hundreds of degrees celsius. Easy. Heatpumps can do that. All you need is a good source of temperature gradient and electricity. You can go much higher than that with resistive heating, plasma heating, inductive heating, etc. It's just a matter of applying enough power to these things. You eliminate a lot of emissions, supply issues and other logistics by doing so. That's where the cost savings are going to be.

evronm 3y ago

Am I the only one having DNS issues with this site? For some reason, no matter which DNS server I query, it resolves to my router, yet it seems most everyone reaches it without issue.

voisin 3y ago

The biggest problem I see, as someone who has tried to get a heat pump installed in both residential and commercial settings, is that the trades are very, very slow to change. They have, by and large, built their careers on burning natural gas and are not willing to entertain the idea that it isn’t necessary, particularly where the new product requires less maintenance which is their bread and butter. It will change, but oh so slowly.