Converting Geothermal System to Closed-Loop
Currently have open loop water based geo-thermal (about a 3 ton unit) drawing from private well and discharging to local stream. Local PFAS contamination is driving state environmental department to condemn all private wells in area of contamination if they can be served by city water.
Our well is targeted and a state grant is funding the extension of the nearest city water system to our neighborhood. We will be losing the well in 2024 at the latest
Started looking at converting the existing open loop to closed loop and now wondering best approach.
Property surrounding home is pretty heavily wooded and unsuited for trench approach, am guessing we will have to either bore vertically or use directional drilling to set the closed loop heat exchanger loops.
Have seen plastic “slinky” systems for the heat exchanger. Plastic does not seem like an ideal heat exchanger material. Working fluid in these seems to be either a dilute mix of Propylene Glycol or a dilute mix of Methanol. Both have proponents and opponents for varying reasons including environmental.
Recently saw another system using copper tubing for the heat exchangers, probably more expensive although less is needed as the tubing is smaller, 1/4 or 1/2 instead of 3/4 or 1 for plastic. Working fluid is advertised as R410a.
What factors influence (or should influence) selection of a closed loop geo-thermal approach?
What should I be looking at. Cost is not necessarily the top driving factor but is a consideration.
Our property does not have access to natural gas, currently we are all electric (no pun intended). Life does seem to be a consecutive set of problems to solve some days.
Thanks for any insight or comments anyone may have.
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