You have a lot of knowledge about the kind of rock and the range of well yields in your service area, and you can use this knowledge to install better-performing open-loop geothermal heat pump systems. You can even use the geology to drill the supply and return wells right next to each other, without having short circuit flow go between them. A limestone formation with good well yields that you know has hard water can be an excellent source aquifer for an open-loop geothermal system because you understand the water quality.

When you drill a residential well that has a yield that is more than the customer will need in the home, you can complete this well so it will be able to supply both the water needs in the home and also supply the water for the open-loop heat pump system. Now what about the return or recharge well? A rule-of-thumb for the return well states that it should have a yield at least twice the rate of flow of water that will be recharged. This rule-of-thumb doesn’t apply in every case, and you can use your local knowledge of the subsurface conditions to drill a return well that has no yield because it is not deep enough to reach the water table. You will learn how to be certain that the return well with no yield will dependably recharge the flow of water from the heat pump system.

This presentation will use real-world case-history examples to show how you can use the geology and the site conditions to your advantage to construct better-performing open loop systems. The examples in this presentation will illustrate techniques and designs that can be used in many locations across the US.