Idea: DIY Ground Source add on to Air Source Heat Pumps

gascort · 01-18-15, 08:23 PM

How about a ground source assist system that acts as an air preheater (or precooler in summer) for existing air source heat pumps?
You could lay the pipe, as much as you could handle, DIY... you could make the ground loops smaller than a traditional system if you only planned on using it in peak times and using the energy in the air for non-peak.
For the heat exchanger, purchase a big, used A/C unit from a local AC company that's scrapping it. Just needs to be bigger than your current condenser. Easily done for $50 or so - just can't have a big leak.
Wrap new unit's coils around the existing unit and seal gaps.
Add some pretty easy controls, a thermostat so you can use it in optimal times - like when the ground is significantly warmer(in winter) than the air, and a pump, and move the coolant through the lines that used to hold refrigerant in the recycled condenser. This wouldn't have any compression or anything and could be done easily by a DIYer, and wouldn't involve water inside the house or any new equipment. It would just improve the performance of your system in peak demand times by supplying it with ambient air that's closer do your desired temperature.
There appears to be nothing online that combines GSHP and existing ASHP but this would be a (relatively) easy add-on, half the cost of any GS system since you would have no special equipment except for the trench and pump to buy. And it could be done in a small fashion without committing 100% to it and ditching your ASHP and existing equipment.

I just purchased a home with two ASHPs and a big yard... the trench or well, ground loops... is obviously a big consideration for anyone doing GSHP but this might reduce cost enough for me to try it... just don't know if it would be worth it in terms of increased efficiency.

01-18-15, 08:23 PM	#1
gascort Helper EcoRenovator Join Date: Feb 2009 Location: Saint Louis, MO Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	Idea: DIY Ground Source add on to Air Source Heat Pumps How about a ground source assist system that acts as an air preheater (or precooler in summer) for existing air source heat pumps? You could lay the pipe, as much as you could handle, DIY... you could make the ground loops smaller than a traditional system if you only planned on using it in peak times and using the energy in the air for non-peak. For the heat exchanger, purchase a big, used A/C unit from a local AC company that's scrapping it. Just needs to be bigger than your current condenser. Easily done for $50 or so - just can't have a big leak. Wrap new unit's coils around the existing unit and seal gaps. Add some pretty easy controls, a thermostat so you can use it in optimal times - like when the ground is significantly warmer(in winter) than the air, and a pump, and move the coolant through the lines that used to hold refrigerant in the recycled condenser. This wouldn't have any compression or anything and could be done easily by a DIYer, and wouldn't involve water inside the house or any new equipment. It would just improve the performance of your system in peak demand times by supplying it with ambient air that's closer do your desired temperature. There appears to be nothing online that combines GSHP and existing ASHP but this would be a (relatively) easy add-on, half the cost of any GS system since you would have no special equipment except for the trench and pump to buy. And it could be done in a small fashion without committing 100% to it and ditching your ASHP and existing equipment. I just purchased a home with two ASHPs and a big yard... the trench or well, ground loops... is obviously a big consideration for anyone doing GSHP but this might reduce cost enough for me to try it... just don't know if it would be worth it in terms of increased efficiency.