12 ms·

It is probably far more cost effective to buy a new air source heatpump. They’re so efficient and work well at low temps now. I have infloor radiant heat at a r

It is probably far more cost effective to buy a new air source heatpump. They’re so efficient and work well at low temps now. I have infloor radiant heat at a rural house in upper Midwest, have thought a lot about using solar heat pipes and adding a storage tank, and it’s all so fiddly, pipes and pumps and manifolds and glycol and maintenance, all custom, all expensive. I’m almost certainly better off with PV panels and off the shelf heat pumps.

londons_explore 4y ago
Even a modern air source heat pump typically doesn't beat gas for $/kwh. Even in europe where gas prices are sky high, electricity still costs more when you look at the seasonal efficiency of heat pumps, which is typically advertised around 4.4, but various studies show that in most real world scenarios you typically won't reach the quoted lab numbers, so expect to get more like 2.5-3.0. Study: https://www.sciencedirect.com/science/article/pii/S0378778821006496 https://www.sciencedirect.com/science/article/pii/S037877882...
- teucris 4y ago
  Thus the solar panels. So long as the installation proves to make financial sense, the PV production offsets the heat pump efficiency, even in winter months.
  - londons_explore 4y ago
    It would make even more sense to sell that power back to the grid, and then spend the $$$ earned on gas, which would work out cheaper overall. Obviously in many parts of the world, market distortion means the buy price and sell price for electricity is very different, and in that case a heat pump might make sense to combine with PV.
  - jonstewart 4y ago
    Exactly. Also, the top commenter noted that only electricity was available and currently was relying on massively inefficient baseboard heaters. Solar panels and heat pumps also have great rebate programs and eventually gas will be phased out. Some US cities are now banning gas on new construction in the near future. The point is that custom solar/geothermal installs seem neat and efficient —- waste not, want not — but probably have a hard time competing with the economies of scale and low maintenance of PV panels and air source heat pumps.
  - jonstewart 4y ago
    Selling PV electricity back to the grid is almost always many times worse, depending on state incentives, than consuming the electricity. For example, my utility sells electricity to me at 9 cents/KWh, but only buys from me at 2.5 cents, and charged me a fixed monthly fee for the meter to boot. If the commenter’s house doesn’t have gas, then it doesn’t seem to make sense to install it, and the price differential in the US isn’t as great as in the UK (how’s that Brexit thing working out?).
    - teucris 4y ago
      Huh. We have a 1:1 credit system here in Washington.
      - whafro 4y ago
        And Massachusetts.
      - cinntaile 4y ago
        Considering solar owners are all pushing electricity onto the grid at the same time, when it is needed the least, such a system doesn't make sense. There are real costs associated with getting rid of all that unwanted energy.
        teucris 4y ago
        > when it is needed the least I don’t think this is true in many areas. In our area, during the summer the neighborhood is running A/C when the sun is at its peak. During the winter, heating. Also the transport loss from a power station is nothing to sneeze at - my understanding is that locally produced power often just results in reduced demand on the larger grid.
        ridgeguy 4y ago
        I think solar makes sense for most who use air conditioning. That's a load matched pretty closely to the timing of PV generation. Here in the Sierra foothills, it's been a blazing hot summer. About 90% of our PV generation powered our home air conditioning. We shipped very little energy to the grid on hot days. And it was awesome to have a comfortable environment without sucking grid power on the days when it hit 113°F.
  - distances 4y ago
    This may work in mild climates, but the areas where winter heating is most needed will have the solar panels under a bed of snow during the winter months. Additionally, winter months are usually the cloudy ones. It's not very uncommon to have just a couple of sunny days per month in European winters, driving down solar gains even if there's no snow cover.
    - jws 4y ago
      It's not as bad as this. In climates where you will have a bed of snow during the winter months, your optimum tilt angle for a fixed solar panel is something like 30° off of vertical or steeper. I find that on mine the snow falls off since it is a south facing, steep, dark surface. You engineer to make sure you have enough energy captured each month to meet that months needs. That might lead you to a tilting mount, or just a fixed angle and having surplus energy most months. In my case, panels were much more expensive when I designed my system, I initially roof mounted them, but when replacing the roof under them I moved them to a pole and went with a tilting mount and manually move the panels twice a year. My load is much higher in the summer, but I still need some power in the winter. And northern winters can be cloudy a lot and have limited sun even on a clear day. At my location there is about a factor of 5 difference in solar energy per square meter per month. So you design for each month and then pick a solution that is best. In my case the summer load is so high that even though I get 5 times the energy, it is still the driving force on sizing the system.
      - starlust2 4y ago
        They are on a pole on your roof or you moved them to the ground?
        jws 4y ago
        I moved them to the ground. The roof pitch is about 1:1 and I’m not feeling like trying to stick to it any more. The pole puts everything at a comfortable working height.
      - distances 4y ago
- titzer 4y ago
  That's kind of disappointing news. I had a skim through the article and was surprised to find that it's all based on models. There wasn't a single empirical measurement of an installation of either kind. Not that I don't believe in modeling and its usages, but I am going to radically discount the findings of this paper because there was no actual experiment performed here, just fiddling with models.
  - londons_explore 4y ago
    Give it a re-read. They collected data from actual houses (although granted only 6 boiler-years worth of hourly data), then fitted a best fit model to that data, then used the model for their conclusions. They did that because they needed to compare the manufacturers datasheet lab figures to the real world figures, but there are 10+ variables that affect efficiency, and a direct comparison isn't possible unless all the variables match - hence using a model to act as the 'convertor'.
- connicpu 4y ago
  That's highly dependent on your local electricity and gas prices. A quick google search tells me residential electricity in Germany costs about 2-3x what it does where I live in the northwest US. We're on mostly government owned hydro power and electric prices have been stable for a long time, meanwhile gas keeps going up. EDIT: Did some quick math using my last power bill, at current prices a heat pump just needs to be about 2.9 average COP to beat gas in cost for me, if gas keeps going up that'll keep dropping!
- mint2 4y ago
  Claims like that really aren’t helpful without numbers backing them up the cited paper gives the efficiency of heat pump but we’re missing multiple crucial values to get from there to a comparison of heating costs Edit: https://great-home.co.uk/air-source-heat-pump-running-costs-calculator/ https://great-home.co.uk/air-source-heat-pump-running-costs-... At current average British prices of 28p for electricity and 7p for gas, and using averages for both it looks like the commenter was mostly correct. Not 100% if the spf Gives the realistic cop In a new build that opted to forgo any gas connection, I’d be interested in seeing the costs from the substantial infra savings and hookup savings.
  - londons_explore 4y ago
    From that paper, the average COP measured was 3.06 (averaged between 2 and 7 degree outdoor temperatures, typical of the UK). The UK electricity price is currently fixed at 34p/kwh for electricity and 10.3p for gas. A new gas boiler has a COP(efficiency) of 1.054 (it can manage efficiency higher than 100% because gas is metered by the 'lower heating value', which assumes the exhaust gas escapes as steam, but the boilers actually condense most of that steam to water, getting additional energy out). So. Total price is: Gas: 10.3/1.054 = 9.77p/kwh in your home. Total ASHP price is: 34p/3.06 = 11.1p/kwh in your home. And this analysis ignores the fact that ASHP's typically have much worse efficiency making hot shower water (which a gas boiler doesn't), and obviously also have considerably higher upfront costs too.
    - jandrese 4y ago
      However, the ASHP can also be used to cool your home in the summer. In the past this has been a dubious benefit for most of northern Europe, but heat waves have been getting stronger, last longer, and happen more frequently as time goes on. This is turning into a serious consideration. Also, you can theoretically power a ASHP with renewable energy, while there are few if any carbon neutral replacements for natural gas.
      - londons_explore 4y ago
        Most boilers purchased today allow use with a Hydrogen mix, and some under development allow 100% hydrogen. Before the widespread extraction of natural gas, towns were powered with 'town gas', which is ~50% Hydrogen, so this is very much proven tech. There are a bunch of potential ways to make green hydrogen too. So, there very much is a path to green with a gas boiler.
- smileysteve 4y ago
  This seems like a (regulated) pricing error. There should be no economic way that a high efficiency turbine produces and distributes electricity to heat homes at a greater than 1:1 ratio compared to storing, pressurizing, and delivering, then burning in irregularly maintained consumer homes. Likely the error is that gas pipes to the house are subsidized (albeit the electrical likely is too, with heat pumps and induction stoves, the gas lines are unnecessarily redundant)
  - dahfizz 4y ago
    "high efficiency" turbines are not all that efficient. Burning gas releases 100% of the available energy as heat. Converting that gas to electricity is << 50% efficient. You also lose ~5% just transmitting the electricity to homes. Also, electricity from gas is relatively expensive. Other sources like coal or hydro are cheaper, which lowers the average cost of electricity.
    - smileysteve 4y ago
      But gas turbines should be more efficient than a burner under a boiler or a burner in a furnace. Yes, solar, wind, hydro, nuclear should be cheaper per unit (coal is not usually cheaper than gas in the US)
      - dahfizz 4y ago
        95% efficient gas furnaces are the norm for newer houses[1]. Getting electricity out of gas is fundamentally harder than getting heat out of it. [1] https://iwae.com/resources/articles/95-afue-gas-furnace-work.html https://iwae.com/resources/articles/95-afue-gas-furnace-work...
        pfdietz 4y ago
        There is a large second law loss even in a "95% efficient" furnace. A gas-fired heat pump would have efficiency much higher than that.
      - 4y ago
2Gkashmiri 4y ago
interesting. i have a PV system. i want to use the half installed central heating system (only piping laid down) (no boiler or FCU/room unit) and i have this crazy idea. use solar water heater to heat water, that feeds into a water storage tank, that water gets heated MORE by an air source water heater and a small circulation pump uses that water storage to heat the house. i am hoping, since we currently have 0 whole house heating, this would be better than nothing and the problem of not having consistent electricity to run the air source heat pump all times would be alleviated somehow by using solar water. is that crazy?
- jonstewart 4y ago
  I assume you’re on the grid? Yeah, sadly, it’s crazy. Solar heaters are expensive and require a large area to get decent BTUs out of. If you can find free solar heaters that someone’s giving away, that can make the difference, but they’re often a few thousand dollars and that’s about equivalent to a Fujitsu or Mitsubishi heat pump base install, especially when you factor in all the extra plumbing and pumps to/from the solar thermal array. WORSE, there’s maintenance. You’ve got the potential for leaks (probability rises to 1.0 over the years), and you have to worry about the water freezing. That can be mitigated by using a glycol mix, but then you’ve got glycol and that lowers the efficiency. And then you have to think about climate. Is it reliably sunny in the winter? Or is it only sunny 1 out of 3 days, with long stretches of gray days? You are probably better off plowing that money into efficiency/insulation improvements to lower the overall heat load (and those improvements often have zero maintenance). I’d suggest looking into an air source heatpump that can produce domestic hot water, paired with a large storage tank. Check out Artic Heat Pumps: https://www.arcticheatpumps.com/ https://www.arcticheatpumps.com/
- jonstewart 4y ago
  Oh, also: an air source water heater would need an external heat source—otherwise you’ve just made a closed system and won’t be able to heat the house beyond what solar thermal provides, plus heat loss of the house.
- mderazon 4y ago
  I am currently looking to do something similar. I have zero heating in my house at the moment and have a 300L (65 gallon) thermosiphon solar water heater [1] (tank plus panels all in one system) that gives me plenty hot sanitary water. I am looking to install an hydronic fan coil [2] radiator in my rooms and need water to heat them - I thought to use the excess heat from the solar heater to supply hot water to the fan coil units but I am not sure how do do that. If you have an idea, please share. 1. https://sol-aqua.com/thermosiphon-solar-water-heater/ https://sol-aqua.com/thermosiphon-solar-water-heater/ 2. https://www.arcticheatpumps.com/heat-pump-fan-coils.html https://www.arcticheatpumps.com/heat-pump-fan-coils.html
xienze 4y ago
> They’re so efficient and work well at low temps now. Can someone provide me model numbers for these heat pumps that “work well” at low temperatures? I’ve been through more than a few over the decades and currently have a Trane from last year and yep, still doesn’t hold up very well once the temperature hits freezing. Don’t get me wrong, I like heat pumps, but my eyes roll into the back of my skull when I hear over and over again that they’re “so efficient now” at low temperatures.
- jonstewart 4y ago
  Fujitsu XLTH: https://www.fujitsugeneral.com/us/residential/technology/xlth-low-temp-heating.html https://www.fujitsugeneral.com/us/residential/technology/xlt... Mitsubishi Hyper Heat and H2i Plus: https://www.mitsubishicomfort.com/articles/what-is-a-heat-pump https://www.mitsubishicomfort.com/articles/what-is-a-heat-pu... Efficiency with these heat pumps severely decreases when temps go below 0F, but they still produce heat. Their sites are admittedly not all that clear. GreenBuildingAdvisor.com has a ton of useful info on it, like https://www.greenbuildingadvisor.com/question/cold-weather-performance-reports-from-minisplit-owners https://www.greenbuildingadvisor.com/question/cold-weather-p....
- oittaa 4y ago
  If you actually live in an area where temperatures drop below -30C regularly, you might want to consider a ground source heat pump. They are a bit more expensive than the typical air source heat pumps since there's some digging involved, but for a new house they aren't that much more expensive since there's already digging for electricity, plumbing, etc. For example ground source heat pumps are getting quite popular in Finland.
  - xienze 4y ago
    Who’s talking about -30C? I’m talking about 32F, or 0C. I’ve yet to be impressed by a heat pump once the temperature gets at or especially below freezing. Geothermal heat pumps are great but at least in the US they are wildly expensive compared to traditional ones. You either need a large lot for horizontal laying of the pipe or a DEEP hole if going vertical ($$$). Plus they’re uncommon enough that contractors are happy to charge a serious premium.

londons_explore 4y ago

Even a modern air source heat pump typically doesn't beat gas for $/kwh. Even in europe where gas prices are sky high, electricity still costs more when you look at the seasonal efficiency of heat pumps, which is typically advertised around 4.4, but various studies show that in most real world scenarios you typically won't reach the quoted lab numbers, so expect to get more like 2.5-3.0. Study: https://www.sciencedirect.com/science/article/pii/S0378778821006496 https://www.sciencedirect.com/science/article/pii/S037877882...

teucris 4y ago
Thus the solar panels. So long as the installation proves to make financial sense, the PV production offsets the heat pump efficiency, even in winter months.
- londons_explore 4y ago
  It would make even more sense to sell that power back to the grid, and then spend the $$$ earned on gas, which would work out cheaper overall. Obviously in many parts of the world, market distortion means the buy price and sell price for electricity is very different, and in that case a heat pump might make sense to combine with PV.
- jonstewart 4y ago
  Exactly. Also, the top commenter noted that only electricity was available and currently was relying on massively inefficient baseboard heaters. Solar panels and heat pumps also have great rebate programs and eventually gas will be phased out. Some US cities are now banning gas on new construction in the near future. The point is that custom solar/geothermal installs seem neat and efficient —- waste not, want not — but probably have a hard time competing with the economies of scale and low maintenance of PV panels and air source heat pumps.
- jonstewart 4y ago
  Selling PV electricity back to the grid is almost always many times worse, depending on state incentives, than consuming the electricity. For example, my utility sells electricity to me at 9 cents/KWh, but only buys from me at 2.5 cents, and charged me a fixed monthly fee for the meter to boot. If the commenter’s house doesn’t have gas, then it doesn’t seem to make sense to install it, and the price differential in the US isn’t as great as in the UK (how’s that Brexit thing working out?).
  - teucris 4y ago
    Huh. We have a 1:1 credit system here in Washington.
    - whafro 4y ago
      And Massachusetts.
    - cinntaile 4y ago
      Considering solar owners are all pushing electricity onto the grid at the same time, when it is needed the least, such a system doesn't make sense. There are real costs associated with getting rid of all that unwanted energy.
      - teucris 4y ago
        > when it is needed the least I don’t think this is true in many areas. In our area, during the summer the neighborhood is running A/C when the sun is at its peak. During the winter, heating. Also the transport loss from a power station is nothing to sneeze at - my understanding is that locally produced power often just results in reduced demand on the larger grid.
      - ridgeguy 4y ago
        I think solar makes sense for most who use air conditioning. That's a load matched pretty closely to the timing of PV generation. Here in the Sierra foothills, it's been a blazing hot summer. About 90% of our PV generation powered our home air conditioning. We shipped very little energy to the grid on hot days. And it was awesome to have a comfortable environment without sucking grid power on the days when it hit 113°F.
- distances 4y ago
  This may work in mild climates, but the areas where winter heating is most needed will have the solar panels under a bed of snow during the winter months. Additionally, winter months are usually the cloudy ones. It's not very uncommon to have just a couple of sunny days per month in European winters, driving down solar gains even if there's no snow cover.
  - jws 4y ago
    It's not as bad as this. In climates where you will have a bed of snow during the winter months, your optimum tilt angle for a fixed solar panel is something like 30° off of vertical or steeper. I find that on mine the snow falls off since it is a south facing, steep, dark surface. You engineer to make sure you have enough energy captured each month to meet that months needs. That might lead you to a tilting mount, or just a fixed angle and having surplus energy most months. In my case, panels were much more expensive when I designed my system, I initially roof mounted them, but when replacing the roof under them I moved them to a pole and went with a tilting mount and manually move the panels twice a year. My load is much higher in the summer, but I still need some power in the winter. And northern winters can be cloudy a lot and have limited sun even on a clear day. At my location there is about a factor of 5 difference in solar energy per square meter per month. So you design for each month and then pick a solution that is best. In my case the summer load is so high that even though I get 5 times the energy, it is still the driving force on sizing the system.
    - starlust2 4y ago
      They are on a pole on your roof or you moved them to the ground?
      - jws 4y ago
        I moved them to the ground. The roof pitch is about 1:1 and I’m not feeling like trying to stick to it any more. The pole puts everything at a comfortable working height.
    - distances 4y ago
titzer 4y ago
That's kind of disappointing news. I had a skim through the article and was surprised to find that it's all based on models. There wasn't a single empirical measurement of an installation of either kind. Not that I don't believe in modeling and its usages, but I am going to radically discount the findings of this paper because there was no actual experiment performed here, just fiddling with models.
- londons_explore 4y ago
  Give it a re-read. They collected data from actual houses (although granted only 6 boiler-years worth of hourly data), then fitted a best fit model to that data, then used the model for their conclusions. They did that because they needed to compare the manufacturers datasheet lab figures to the real world figures, but there are 10+ variables that affect efficiency, and a direct comparison isn't possible unless all the variables match - hence using a model to act as the 'convertor'.
connicpu 4y ago
That's highly dependent on your local electricity and gas prices. A quick google search tells me residential electricity in Germany costs about 2-3x what it does where I live in the northwest US. We're on mostly government owned hydro power and electric prices have been stable for a long time, meanwhile gas keeps going up. EDIT: Did some quick math using my last power bill, at current prices a heat pump just needs to be about 2.9 average COP to beat gas in cost for me, if gas keeps going up that'll keep dropping!
mint2 4y ago
Claims like that really aren’t helpful without numbers backing them up the cited paper gives the efficiency of heat pump but we’re missing multiple crucial values to get from there to a comparison of heating costs Edit: https://great-home.co.uk/air-source-heat-pump-running-costs-calculator/ https://great-home.co.uk/air-source-heat-pump-running-costs-... At current average British prices of 28p for electricity and 7p for gas, and using averages for both it looks like the commenter was mostly correct. Not 100% if the spf Gives the realistic cop In a new build that opted to forgo any gas connection, I’d be interested in seeing the costs from the substantial infra savings and hookup savings.
- londons_explore 4y ago
  From that paper, the average COP measured was 3.06 (averaged between 2 and 7 degree outdoor temperatures, typical of the UK). The UK electricity price is currently fixed at 34p/kwh for electricity and 10.3p for gas. A new gas boiler has a COP(efficiency) of 1.054 (it can manage efficiency higher than 100% because gas is metered by the 'lower heating value', which assumes the exhaust gas escapes as steam, but the boilers actually condense most of that steam to water, getting additional energy out). So. Total price is: Gas: 10.3/1.054 = 9.77p/kwh in your home. Total ASHP price is: 34p/3.06 = 11.1p/kwh in your home. And this analysis ignores the fact that ASHP's typically have much worse efficiency making hot shower water (which a gas boiler doesn't), and obviously also have considerably higher upfront costs too.
  - jandrese 4y ago
    However, the ASHP can also be used to cool your home in the summer. In the past this has been a dubious benefit for most of northern Europe, but heat waves have been getting stronger, last longer, and happen more frequently as time goes on. This is turning into a serious consideration. Also, you can theoretically power a ASHP with renewable energy, while there are few if any carbon neutral replacements for natural gas.
    - londons_explore 4y ago
      Most boilers purchased today allow use with a Hydrogen mix, and some under development allow 100% hydrogen. Before the widespread extraction of natural gas, towns were powered with 'town gas', which is ~50% Hydrogen, so this is very much proven tech. There are a bunch of potential ways to make green hydrogen too. So, there very much is a path to green with a gas boiler.
smileysteve 4y ago
This seems like a (regulated) pricing error. There should be no economic way that a high efficiency turbine produces and distributes electricity to heat homes at a greater than 1:1 ratio compared to storing, pressurizing, and delivering, then burning in irregularly maintained consumer homes. Likely the error is that gas pipes to the house are subsidized (albeit the electrical likely is too, with heat pumps and induction stoves, the gas lines are unnecessarily redundant)
- dahfizz 4y ago
  "high efficiency" turbines are not all that efficient. Burning gas releases 100% of the available energy as heat. Converting that gas to electricity is << 50% efficient. You also lose ~5% just transmitting the electricity to homes. Also, electricity from gas is relatively expensive. Other sources like coal or hydro are cheaper, which lowers the average cost of electricity.
  - smileysteve 4y ago
    But gas turbines should be more efficient than a burner under a boiler or a burner in a furnace. Yes, solar, wind, hydro, nuclear should be cheaper per unit (coal is not usually cheaper than gas in the US)
    - dahfizz 4y ago
      95% efficient gas furnaces are the norm for newer houses[1]. Getting electricity out of gas is fundamentally harder than getting heat out of it. [1] https://iwae.com/resources/articles/95-afue-gas-furnace-work.html https://iwae.com/resources/articles/95-afue-gas-furnace-work...
      - pfdietz 4y ago
        There is a large second law loss even in a "95% efficient" furnace. A gas-fired heat pump would have efficiency much higher than that.
    - 4y ago

2Gkashmiri 4y ago

interesting. i have a PV system. i want to use the half installed central heating system (only piping laid down) (no boiler or FCU/room unit) and i have this crazy idea. use solar water heater to heat water, that feeds into a water storage tank, that water gets heated MORE by an air source water heater and a small circulation pump uses that water storage to heat the house. i am hoping, since we currently have 0 whole house heating, this would be better than nothing and the problem of not having consistent electricity to run the air source heat pump all times would be alleviated somehow by using solar water. is that crazy?

jonstewart 4y ago
I assume you’re on the grid? Yeah, sadly, it’s crazy. Solar heaters are expensive and require a large area to get decent BTUs out of. If you can find free solar heaters that someone’s giving away, that can make the difference, but they’re often a few thousand dollars and that’s about equivalent to a Fujitsu or Mitsubishi heat pump base install, especially when you factor in all the extra plumbing and pumps to/from the solar thermal array. WORSE, there’s maintenance. You’ve got the potential for leaks (probability rises to 1.0 over the years), and you have to worry about the water freezing. That can be mitigated by using a glycol mix, but then you’ve got glycol and that lowers the efficiency. And then you have to think about climate. Is it reliably sunny in the winter? Or is it only sunny 1 out of 3 days, with long stretches of gray days? You are probably better off plowing that money into efficiency/insulation improvements to lower the overall heat load (and those improvements often have zero maintenance). I’d suggest looking into an air source heatpump that can produce domestic hot water, paired with a large storage tank. Check out Artic Heat Pumps: https://www.arcticheatpumps.com/ https://www.arcticheatpumps.com/
jonstewart 4y ago
Oh, also: an air source water heater would need an external heat source—otherwise you’ve just made a closed system and won’t be able to heat the house beyond what solar thermal provides, plus heat loss of the house.
mderazon 4y ago
I am currently looking to do something similar. I have zero heating in my house at the moment and have a 300L (65 gallon) thermosiphon solar water heater [1] (tank plus panels all in one system) that gives me plenty hot sanitary water. I am looking to install an hydronic fan coil [2] radiator in my rooms and need water to heat them - I thought to use the excess heat from the solar heater to supply hot water to the fan coil units but I am not sure how do do that. If you have an idea, please share. 1. https://sol-aqua.com/thermosiphon-solar-water-heater/ https://sol-aqua.com/thermosiphon-solar-water-heater/ 2. https://www.arcticheatpumps.com/heat-pump-fan-coils.html https://www.arcticheatpumps.com/heat-pump-fan-coils.html

xienze 4y ago

> They’re so efficient and work well at low temps now. Can someone provide me model numbers for these heat pumps that “work well” at low temperatures? I’ve been through more than a few over the decades and currently have a Trane from last year and yep, still doesn’t hold up very well once the temperature hits freezing. Don’t get me wrong, I like heat pumps, but my eyes roll into the back of my skull when I hear over and over again that they’re “so efficient now” at low temperatures.

jonstewart 4y ago
Fujitsu XLTH: https://www.fujitsugeneral.com/us/residential/technology/xlth-low-temp-heating.html https://www.fujitsugeneral.com/us/residential/technology/xlt... Mitsubishi Hyper Heat and H2i Plus: https://www.mitsubishicomfort.com/articles/what-is-a-heat-pump https://www.mitsubishicomfort.com/articles/what-is-a-heat-pu... Efficiency with these heat pumps severely decreases when temps go below 0F, but they still produce heat. Their sites are admittedly not all that clear. GreenBuildingAdvisor.com has a ton of useful info on it, like https://www.greenbuildingadvisor.com/question/cold-weather-performance-reports-from-minisplit-owners https://www.greenbuildingadvisor.com/question/cold-weather-p....
oittaa 4y ago
If you actually live in an area where temperatures drop below -30C regularly, you might want to consider a ground source heat pump. They are a bit more expensive than the typical air source heat pumps since there's some digging involved, but for a new house they aren't that much more expensive since there's already digging for electricity, plumbing, etc. For example ground source heat pumps are getting quite popular in Finland.
- xienze 4y ago
  Who’s talking about -30C? I’m talking about 32F, or 0C. I’ve yet to be impressed by a heat pump once the temperature gets at or especially below freezing. Geothermal heat pumps are great but at least in the US they are wildly expensive compared to traditional ones. You either need a large lot for horizontal laying of the pipe or a DEEP hole if going vertical ($$$). Plus they’re uncommon enough that contractors are happy to charge a serious premium.