Ground Source heat Pump

[G. S. Hudson]

I have a 15-year old heat pump, and before I pay a "professional" to replace it with a ground source heat pump, I thought I might play around a bit with it first.

For example:

Rather than use coils of plastic pipe in my .5 acre pond as a heat exchanger, why not use the pond water directly? If I remove the housing and the fan motor apparatus, then dunk the exchanger coils in a water-tight tank, I could run cool water from the pond directly into the tank. The energy to pump cool water uphill into the tank would be nearly offset by gravity pulling the warm water back into the pond. (Note: I am in North Carolina, and heat pumps usually mean air conditioning.)

What is the worst thing that could happen? I could ruin outside exchanger, and have to replace it with GSHP, which is what I want to do anyway.

If anyone has experience with these systems, I would like to hear from you.

Thanks,
G. S. Hudson
Wake Forest, NC

[Rob Beckers]

Hi G.S.,

If there's enough plastic pipe in the pond for efficient heat exchanging there shouldn't be much difference at all between running water directly through, or using the plastic pipe heat exchanger.

The heat pumps in this area are all ground water based (running ground water from a well through the heat pump, and back into a second return well). The heat pump has a heat exchanger inside, pushing/pulling heat from the refrigerant to/from the ground water, and for heat pumps running directly on well water it is made from a different material that is more corrosion resistant than that used in regular heat pumps. Of course, it also gives manufacturers a reason to charge more. That may be one issue you run into (accelerated corrosion). Then again, you're not planning to run this for the next 20 years. Keeping gunk out of the heat pump, especially with pond water, could be another issue (stuck frogs and such :eek:)...

-RoB-