Geothermal with Well Water

HERE IS A RECENT Q & A WITH AN INQUISITIVE GEOEXCHANGE CLIENT REGARDING GEOTHERMAL USING WELL-WATER:

Q: What would be the approximate electric charge per month for the geothermal heating in a house that is 3600 square feet using wellwater?
A: It will cost you ¼ to 1/5 of regular electric heating because you have a radiant floor and relatively warm wellwater compared to a closed loop. This is the most ideal geo scenario for efficiency. We have a heat sheet which shows efficiencies of different systems. As regular fuel prices escalate you will be immune to that and even if electricity prices rise much, you’ll still be paying only ¼ or 1/5 as much as everyone else. Rising energy prices is where geoexchange stands out.

Q: Could the run-off be used to irrigate the vegetable gardens?
A: Yes, although you’ll get more runoff in the winter than in the summer. How much extra would it cost to set this system up? In one proposal we run the runoff pipe back to near the well which can be extended to the pond or allowed to seep back into the aquifer. You can extend it at low cost with a lower grade of pipe from what we use down the well. You can extend it later by yourself.

Q: What is the anti freeze solution that is used in the geo thermal process?
A: There is no antifreeze used in this scenario. Antifreeze is used in closed loop installations only.

Q: What kind of maintenance and upgrading could we expect to do over the next fifteen years on the system?
A: None, unless your water is of poor quality in which case the heat pump heat exchanger may have to be cleaned. Speaking of which, it is best to send us a water test report. Our main concern would be sulfur in the wellwater. I’ve had a well pump has run since 1990 without a problem. We can do an annual inspection as with a conventional heating system, but it would typically be to check on operating parameters and can safely be extended to every 2 years or more after the first year.

Q: How much wear and tear does the system cause the pump?
A: The pump in question is sized to run the irrigation system as well. Here, we spec’d 22gallons per minute but may be able to reduce that depending on the irrigation requirements. The heat pump would use 6 gallons per minute (gpm) only when it’s running.

Q: How much water per day does the process use?
A: In a brutal cold snap, here in Vancouver, it would run 6 x 60 minutes x 24 hrs = 8,640 gallons per day but in reality it will run 3hrs avg/day or 1080gallons. By comparison at my house I irrigate 8,000 gallons/day every day in the summer for 2 acres.

Q: I don’t quite understand the geothermal process. Could you give a simple explanation?
A: The heat pump absorbs low level heat from the groundwater which is then returned and the heat is upgraded to a higher temp via the same refrigerant phase change process as in your fridge.