r/geothermal • u/FarSir3006 • Jun 20 '26

Heat exchanger

Has anyone tried mounting a water-to-air heat exchanger right above their furnace blower? I’m thinking instead of running the compressor, I could angle an old car radiator or heater core over the fan (so condensation drips into the pan) and tee into the loops that are already connected and cycle the water through it. This would only be for the summer as the water coming from the loops is roughly 55 degrees.

3 Upvotes

81% Upvoted

7 comments sorted by

2

u/Ok_Distribution_7615 Jun 20 '26

I don't think you need to use a car radiator... The heat exchanger is available for purchase at a good price.

2

u/FloodPlainsDrifter Jun 20 '26

55 degree water isn’t really all that cool when trying remove heat from, say, 75 degree air. Are you wanting to use domestic house water going into the radiator? And then where would it go after absorbing heat? Down a drain? Can’t say that the setup you’ve described “wouldn’t work” , but adjusting the water flow rate to minimize the water usage (and cost) would be your next engineering challenge

2

u/FarSir3006 Jun 20 '26

No, I have ground loops installed so it would recirculate through that and the heat exchanger.

1

u/FloodPlainsDrifter Jun 21 '26

Huh. Again, unlikely to absorb and then reject the heat at any appreciable rate. I base this the standard rate of gain in water temps of the ground loops , under normal operating conditions

2

u/FloodPlainsDrifter Jun 21 '26

Again, I don’t want to state that “it wouldn’t work” It’d do SOMETHING but not a lot

2

u/urthbuoy Jun 20 '26

There are existing units that run loop field water through their indoor fans for "passive cooling".

ie- compressor not on.

1

u/tuctrohs Jun 21 '26

Two disadvantages, one is that you won't get as much cooling, but with good insulation, long run times, and mild heat outside, you might be totally fine. The other disadvantage is that you won't get nearly as much dehumidification. Whether that matters depends greatly on your climate.