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As I've learned more about heat pumps I've been wondering why we all use air-source cooling for central A/C. We are cooling our condensers with hot summer time

As I've learned more about heat pumps I've been wondering why we all use air-source cooling for central A/C. We are cooling our condensers with hot summer time air when the temperature is much lower just four feet under the yard. The energy requirements would drop way down by cooling the condenser with a water ground loop. Ground loops are seen as expensive for installation, but I don't understand why. It's just plastic tubing buried in the yard. I've been wondering if a hole digging robot could lower the price. The carbon and money savings would be huge if we could bring down the cost of ground loop installation.

chadgeidel 11y ago
I'm just spitballing here, but one has to be concerned about how much heat soaking the ground loop can take before its effectiveness goes down significantly. Dirt is a pretty good insulator. How much will the "ambient dirt temp" increase after X hours of running AC? How long does it take for the heat to dissipate?
- willholloway 11y ago
  That is why its critical to properly size the system. With the right size loop it works well. Also if you figure an ambient air temperature of 80-100 you can raise the dirt temp a lot before its as warm as the air.
danans 11y ago
I very briefly looked into this. It seems to be the same reason that simple and obvious things like solar water heating systems are so expensive in the US, but not elsewhere: Lack of awareness & low demand but few installers who target the eco/luxury niche product at a high price. These systems usually get installed only in high-end homes.
- willholloway 11y ago
  One of the things I've been working on are open source designs that transform sunlight into heat. I used cardboard, black aluminum foil and tacks for much of the heat for my home this past winter. I'm also working on a simple open source design for an outdoor solar thermal panel that heats air to 130F. It can be built using diy vacuum forming and foam insulation. I have a vision of open source diy solar thermal fixing the market failure you are talking about.
- Animats 11y ago
  Climatemaster has about a million US ground-heatsink heat pump installations. In their system, the ground loop is water with antifreeze, not Freon, so there's an additional heat exchanger. Rheem, the big water heater manufacturer, sells solar water heating systems. That's progress; previous solar-only sellers were kind of flaky. (See "hot2o.com", which disappeared.) Solar water heating systems have a reputation for leaking. Buying something that is supposed to last 10-20 years from a small company is a problem.

chadgeidel 11y ago

I'm just spitballing here, but one has to be concerned about how much heat soaking the ground loop can take before its effectiveness goes down significantly. Dirt is a pretty good insulator. How much will the "ambient dirt temp" increase after X hours of running AC? How long does it take for the heat to dissipate?

willholloway 11y ago
That is why its critical to properly size the system. With the right size loop it works well. Also if you figure an ambient air temperature of 80-100 you can raise the dirt temp a lot before its as warm as the air.

danans 11y ago

I very briefly looked into this. It seems to be the same reason that simple and obvious things like solar water heating systems are so expensive in the US, but not elsewhere: Lack of awareness & low demand but few installers who target the eco/luxury niche product at a high price. These systems usually get installed only in high-end homes.

willholloway 11y ago
One of the things I've been working on are open source designs that transform sunlight into heat. I used cardboard, black aluminum foil and tacks for much of the heat for my home this past winter. I'm also working on a simple open source design for an outdoor solar thermal panel that heats air to 130F. It can be built using diy vacuum forming and foam insulation. I have a vision of open source diy solar thermal fixing the market failure you are talking about.
Animats 11y ago
Climatemaster has about a million US ground-heatsink heat pump installations. In their system, the ground loop is water with antifreeze, not Freon, so there's an additional heat exchanger. Rheem, the big water heater manufacturer, sells solar water heating systems. That's progress; previous solar-only sellers were kind of flaky. (See "hot2o.com", which disappeared.) Solar water heating systems have a reputation for leaking. Buying something that is supposed to last 10-20 years from a small company is a problem.