The driller we are talking to about putting in vertical loops says that we can't use an existing well (300 feet depth; it's being replaced by a new well) because the casing would impair the heat exchange. He also says that each loop--we are contemplating three or four 150 foot wells-- must be of equal depth. Is this standard advice?
Hi and welcome, The loop field design standard is plus or minus 10% for length. The topic of a loop in an existing well has been discussed at great depth/sorry/. If the loop were grouted into the existing casing it would provide a thermal link and be effective. If you could obtain your total load from that one loop it would prolly be fine. Connecting that one bore with the new ones would overly complicate matters for the non-diy type. I would be tempted to proceed and run all the loop tails into the building and use balancing valves to ballance the flow, but I am diy addicted. hope this helps Eric
As Eric said you can balance the flow with valves in the basement or a simple approach would be to connect two 150' boreholes in series to match the 300' loop in the existing well. The casing should not be a problem if properly grouted. -Adam Hydrogeologist
