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I have been doing a ton of research on building my own GSHP lately and so this is a great resource! However, what I have found in the process is that for well

by 0x53 4y ago

I have been doing a ton of research on building my own GSHP lately and so this is a great resource! However, what I have found in the process is that for well insulated homes GSHP probably doesn’t make sense. Originally I was considering buying a kit from this site: https://www.123zeroenergy.com/pricing/geo-thermal.html https://www.123zeroenergy.com/pricing/geo-thermal.html But like it says on the page, because air source heat pumps have been getting a lot better they no longer sell the kits. There are a couple of individuals on YouTube who have used similar GSHP kits and had good success. The main challenge is that you need to dig 100ft of deep trenches per ton of cooling. Edit: should be 300ft not 100

cycomanic 4y ago
We just build a house on the west coast of Sweden and we initially considered both a ground or air heat pump. Essentially our builder said with modern houses and heatpumps going for the ground heat pump was really not worth it. Their efficiency gain only becomes significant at outside temperatures below 10 deg C and there were just not enough days of such low temperature. Instead it is better to invest that money into a solar installation.
- cassepipe 4y ago
  Not to say you were wrong since in making that choice but with climate change days of extreme temperatures in both directions will become ever more common so so you may have considered it an investment into the future. Of course you may have other problems by then (a reliable source of food for example)
  - arinlen 4y ago
    > (...) with climate change days of extreme temperatures in both directions (...) This sort of take is unwise. It makes zero sense to invest today in domestic systems with the expectation that at some point in the future there will be extreme events a hand full of times throughout the year. The benefit of shaving a fraction of a percent from the baseline outweighs multipercent gains of hypothetical extreme events that happen a few times a year.
    - bombcar 4y ago
      And you can always add supplemental later. When building spend as much as you can on the building envelope (preventing air, vapor, water movement) and insulation. Those cannot be easily changed at all, but you can relatively easily add another heating or cooling device. And if you build above code minimums (you should!) be sure to have someone knowledgeable calculate the actual heating/cooling load. If you don’t, the HVAC contractor may assume code minimums and oversize the system. Or get systems that are entirely variable. And get every step inspected! Mid build blower door tests are a great thing to do (right after the air seal envelope is up).
      - arinlen 4y ago
        > And you can always add supplemental later. Great point. Investments are made based on expected returns on investment, and we're free to postpone them until they make sense. Spending money hoping to bank on the occurrence of unexpected outcomes simply can't be justified.
        hedora 4y ago
        > Spending money hoping to bank on the occurrence of unexpected outcomes simply can't be justified. I would have agreed a decade ago, but in the one year our house has been standing, it has endured two 100 year events (a heat wave and a rain/windstorm). We overpaid about $1000 to go one size up on the (variable) heat pump / AC and $10-20k to oversize + harden the solar / battery. It has been worth every penny at this point; the solar kept the fridge, freezer and AC happy in > 100F heat during a power outage. That's $500-1000 of food just for the one event, and outages are increasing in frequency. (Air conditioning was mostly unheard of in this area 20 years ago, since it didn't get hot enough to ever run it.) My big concern is that we're already eating into the engineeeing tolerances for the wind rating on the house itself. I do agree that you should consider what can be upgraded later, and put money towards things that are hard to change (insulation, wind ratings, etc.)
        genewitch 4y ago
- dzhiurgis 4y ago
  Similar in Lithuania, where buildings are required to be certified to A++ efficiency. Electric floor heating and air to air heat pump (aka split system) is enough. Solar panels are much better value. Cooling in summer is kinda becoming much bigger issue. For older building even replacing wood furnace with air to water system is enough.
  - patd 4y ago
    Ground heat pumps provide free cooling in the summer for a very limited amount of electricity as the ground will be at 10-15C (depending on where you live) so you don't need to use the compressor and just make the liquid flow to cool down your house. It also has the extra benefit of heating up your ground for the winter period.
    - cycomanic 4y ago
      While that is in principle true, in practice there are quite a few issues. Many heatpumps here are made to heat the water for floor heating but don't transfer heat to air indoors. So you would cool using your floor which isn't very comfortable usually. More importantly because of the above the heat pumps are build for only one directional transfer. If one builds their own system it might make sense to plan for it, but even then it's unlikely that Sweden will become so hot that opening windows will not cool off the house enough. If it comes so far we likely have more pressing problems.
      - vel0city 4y ago
        It would be cool to have a valve to change between a floor heat loop and an air heat exchanger for the inside side of the system. Of course this makes the system more complicated. More complicated means more chances for failure and higher costs for designing and installing.
        patd 4y ago
        Some do wall heating or ceiling heating instead of floor heating. Wall heating/cooling would probably not require two systems.
- fest 4y ago
  While I do agree that it was true a year ago, I wonder if it holds true for current electricity prices? My considerations for going with ground source heat pump were: * the maximum amount of solar that I could install is enough for ground source heat pump, but is a bit short for air source, * what if the seasonal electricity prices get so extreme, that the grid can't maintain 1:1 ratio for the net billing system anymore? * what if the global temperature swings become more extreme?
- froh 4y ago
  Göteborg is below 10°C November to March, five months https://weatherspark.com/y/71566/Average-Weather-in-G%C3%B6teborg-Sweden-Year-Round https://weatherspark.com/y/71566/Average-Weather-in-G%C3%B6t... in contrast sunshine duration and angle in Winter is frickin low. sure that guy wasn't trying to sell sth?
  - Scoundreller 4y ago
    Ground source is also just a lot more work, and often has a large part of the job contracted out from your average HVAC tech.
  - hedora 4y ago
    I assume they made a typo, and meant to write "under 10°C below zero", Modern air source heat pumps are good to -30°C; the old ones were OK to 0°C: https://www.heatpumps.ca/articles/best-low-temperature-heat-pump https://www.heatpumps.ca/articles/best-low-temperature-heat-...
    - tomohawk 4y ago
      As someone who's used air source heat pumps for years, they were good to around 5C, at which point they would start to ice up and need heat pumped out to melt the ice. They were utter crap if you had any kind of winter conditions. I'd love to believe that modern ones are better, but its hard to pull the trigger on them after years of suffering. I currently have oil heat, and love it. Nice hot (not luke warm) air. And if the power goes out, I just fire up a generator and I have good heat, because the blower doesn't take much to run. Having been w/o power for stretches as long as a week during winter, that is a massive benefit over electric heat.
      - briHass 4y ago
        Many modern heat pumps are much better than what you remember. Some maintain their full rated BTU output to 17F, or in the extreme models, 0-5F. They usually output some percentage of full BTU at even lower temps. The common Asian 'mini split' models also use variable fan speeds to maintain higher coil temps and have output air that is warm enough to avoid the 'luke warm' issue of heat pump coils on 'dumb' air handlers that blow full speed. That said, for cold environments, a backup is often required to make up for the performance drop at very cold temps without massively oversizing the system. Hopefully, you have your oil furnace coupled to a heat pump or perhaps supplemental minisplit heads. That is the best of all worlds: the HPs can cover 80-90% of the load, only needing the oil for extremes. Oil is likely to hit 5 a gallon this year, like last, so it would suck to rely entirely on it.
- Too 4y ago
  Air pumps have drawbacks outside of efficiency that are also worth considering. Particularly noise and heat locality. Two properties that combined are not very cosy.
halbritt 4y ago
> air source heat pumps have been getting a lot better Mitsubishi, specifically, makes a heat pump with the marketing vernacular, "H2i" or "hyper heat" which has reasonable efficiency down to -13F/-25C.
- hedora 4y ago
  That's not even the best one any more. Some other systems hit -30C.
  - genewitch 4y ago
    The part with the compressor in it costs $12000-$15000 minimum just for the device, nevermind installation and the rest, and that's for an equivalent to 3-6 ton systems commonly installed. My mini-split system worked fine down to about 10F, then it was defrosting for 10 minutes after every 8 minutes of use or so. I just turned on crypto miners on a few computers to supplement. Laptop crypto mining is useful if you want to keep your hands and wrists warm, hats, blankets, sweaters, and some old 100+ watt light bulbs will also help. All this is to say "you can just get a -30 degree capable system" is out of reach for most people in the world. A large swath of people geographically close to my house still use window or wall HVAC units, rather than ducted systems. I was the only split ductless system my HVAC installer had ever installed - they had to come fix their install 4 times (four!) and eventually i contacted the asurion purchase protection people and got refunded for the cost of the HVAC system. it works fine now, i told the HVAC installer to cut the threaded connectors off everything and sweat all the copper lines together, and it hasn't had an issue since. it was always breaking in the late fall and early spring, where it had to heat at night but cool during the day, it would always break around 11AM. The pressure differentials must have been an afterthought in the design, i guess.
    - Maakuth 4y ago
      Here in Finland you can get a split system good for -30 Celsius for 2-3k€ including installation. Mitsubishi is considered the best, but others are available. My Panasonic has been working fine.

by 0x53 4y ago

cycomanic 4y ago

We just build a house on the west coast of Sweden and we initially considered both a ground or air heat pump. Essentially our builder said with modern houses and heatpumps going for the ground heat pump was really not worth it. Their efficiency gain only becomes significant at outside temperatures below 10 deg C and there were just not enough days of such low temperature. Instead it is better to invest that money into a solar installation.

cassepipe 4y ago
Not to say you were wrong since in making that choice but with climate change days of extreme temperatures in both directions will become ever more common so so you may have considered it an investment into the future. Of course you may have other problems by then (a reliable source of food for example)
- arinlen 4y ago
  > (...) with climate change days of extreme temperatures in both directions (...) This sort of take is unwise. It makes zero sense to invest today in domestic systems with the expectation that at some point in the future there will be extreme events a hand full of times throughout the year. The benefit of shaving a fraction of a percent from the baseline outweighs multipercent gains of hypothetical extreme events that happen a few times a year.
  - bombcar 4y ago
    And you can always add supplemental later. When building spend as much as you can on the building envelope (preventing air, vapor, water movement) and insulation. Those cannot be easily changed at all, but you can relatively easily add another heating or cooling device. And if you build above code minimums (you should!) be sure to have someone knowledgeable calculate the actual heating/cooling load. If you don’t, the HVAC contractor may assume code minimums and oversize the system. Or get systems that are entirely variable. And get every step inspected! Mid build blower door tests are a great thing to do (right after the air seal envelope is up).
    - arinlen 4y ago
      > And you can always add supplemental later. Great point. Investments are made based on expected returns on investment, and we're free to postpone them until they make sense. Spending money hoping to bank on the occurrence of unexpected outcomes simply can't be justified.
      - hedora 4y ago
        > Spending money hoping to bank on the occurrence of unexpected outcomes simply can't be justified. I would have agreed a decade ago, but in the one year our house has been standing, it has endured two 100 year events (a heat wave and a rain/windstorm). We overpaid about $1000 to go one size up on the (variable) heat pump / AC and $10-20k to oversize + harden the solar / battery. It has been worth every penny at this point; the solar kept the fridge, freezer and AC happy in > 100F heat during a power outage. That's $500-1000 of food just for the one event, and outages are increasing in frequency. (Air conditioning was mostly unheard of in this area 20 years ago, since it didn't get hot enough to ever run it.) My big concern is that we're already eating into the engineeeing tolerances for the wind rating on the house itself. I do agree that you should consider what can be upgraded later, and put money towards things that are hard to change (insulation, wind ratings, etc.)
        genewitch 4y ago
dzhiurgis 4y ago
Similar in Lithuania, where buildings are required to be certified to A++ efficiency. Electric floor heating and air to air heat pump (aka split system) is enough. Solar panels are much better value. Cooling in summer is kinda becoming much bigger issue. For older building even replacing wood furnace with air to water system is enough.
- patd 4y ago
  Ground heat pumps provide free cooling in the summer for a very limited amount of electricity as the ground will be at 10-15C (depending on where you live) so you don't need to use the compressor and just make the liquid flow to cool down your house. It also has the extra benefit of heating up your ground for the winter period.
  - cycomanic 4y ago
    While that is in principle true, in practice there are quite a few issues. Many heatpumps here are made to heat the water for floor heating but don't transfer heat to air indoors. So you would cool using your floor which isn't very comfortable usually. More importantly because of the above the heat pumps are build for only one directional transfer. If one builds their own system it might make sense to plan for it, but even then it's unlikely that Sweden will become so hot that opening windows will not cool off the house enough. If it comes so far we likely have more pressing problems.
    - vel0city 4y ago
      It would be cool to have a valve to change between a floor heat loop and an air heat exchanger for the inside side of the system. Of course this makes the system more complicated. More complicated means more chances for failure and higher costs for designing and installing.
      - patd 4y ago
        Some do wall heating or ceiling heating instead of floor heating. Wall heating/cooling would probably not require two systems.
fest 4y ago
While I do agree that it was true a year ago, I wonder if it holds true for current electricity prices? My considerations for going with ground source heat pump were: * the maximum amount of solar that I could install is enough for ground source heat pump, but is a bit short for air source, * what if the seasonal electricity prices get so extreme, that the grid can't maintain 1:1 ratio for the net billing system anymore? * what if the global temperature swings become more extreme?
froh 4y ago
Göteborg is below 10°C November to March, five months https://weatherspark.com/y/71566/Average-Weather-in-G%C3%B6teborg-Sweden-Year-Round https://weatherspark.com/y/71566/Average-Weather-in-G%C3%B6t... in contrast sunshine duration and angle in Winter is frickin low. sure that guy wasn't trying to sell sth?
- Scoundreller 4y ago
  Ground source is also just a lot more work, and often has a large part of the job contracted out from your average HVAC tech.
- hedora 4y ago
  I assume they made a typo, and meant to write "under 10°C below zero", Modern air source heat pumps are good to -30°C; the old ones were OK to 0°C: https://www.heatpumps.ca/articles/best-low-temperature-heat-pump https://www.heatpumps.ca/articles/best-low-temperature-heat-...
  - tomohawk 4y ago
    As someone who's used air source heat pumps for years, they were good to around 5C, at which point they would start to ice up and need heat pumped out to melt the ice. They were utter crap if you had any kind of winter conditions. I'd love to believe that modern ones are better, but its hard to pull the trigger on them after years of suffering. I currently have oil heat, and love it. Nice hot (not luke warm) air. And if the power goes out, I just fire up a generator and I have good heat, because the blower doesn't take much to run. Having been w/o power for stretches as long as a week during winter, that is a massive benefit over electric heat.
    - briHass 4y ago
      Many modern heat pumps are much better than what you remember. Some maintain their full rated BTU output to 17F, or in the extreme models, 0-5F. They usually output some percentage of full BTU at even lower temps. The common Asian 'mini split' models also use variable fan speeds to maintain higher coil temps and have output air that is warm enough to avoid the 'luke warm' issue of heat pump coils on 'dumb' air handlers that blow full speed. That said, for cold environments, a backup is often required to make up for the performance drop at very cold temps without massively oversizing the system. Hopefully, you have your oil furnace coupled to a heat pump or perhaps supplemental minisplit heads. That is the best of all worlds: the HPs can cover 80-90% of the load, only needing the oil for extremes. Oil is likely to hit 5 a gallon this year, like last, so it would suck to rely entirely on it.
Too 4y ago
Air pumps have drawbacks outside of efficiency that are also worth considering. Particularly noise and heat locality. Two properties that combined are not very cosy.

halbritt 4y ago

> air source heat pumps have been getting a lot better Mitsubishi, specifically, makes a heat pump with the marketing vernacular, "H2i" or "hyper heat" which has reasonable efficiency down to -13F/-25C.

hedora 4y ago
That's not even the best one any more. Some other systems hit -30C.
- genewitch 4y ago
  The part with the compressor in it costs $12000-$15000 minimum just for the device, nevermind installation and the rest, and that's for an equivalent to 3-6 ton systems commonly installed. My mini-split system worked fine down to about 10F, then it was defrosting for 10 minutes after every 8 minutes of use or so. I just turned on crypto miners on a few computers to supplement. Laptop crypto mining is useful if you want to keep your hands and wrists warm, hats, blankets, sweaters, and some old 100+ watt light bulbs will also help. All this is to say "you can just get a -30 degree capable system" is out of reach for most people in the world. A large swath of people geographically close to my house still use window or wall HVAC units, rather than ducted systems. I was the only split ductless system my HVAC installer had ever installed - they had to come fix their install 4 times (four!) and eventually i contacted the asurion purchase protection people and got refunded for the cost of the HVAC system. it works fine now, i told the HVAC installer to cut the threaded connectors off everything and sweat all the copper lines together, and it hasn't had an issue since. it was always breaking in the late fall and early spring, where it had to heat at night but cool during the day, it would always break around 11AM. The pressure differentials must have been an afterthought in the design, i guess.
  - Maakuth 4y ago
    Here in Finland you can get a split system good for -30 Celsius for 2-3k€ including installation. Mitsubishi is considered the best, but others are available. My Panasonic has been working fine.