Originally Posted By: Rich Clos
This post was automatically imported from our archived forum.
Being in the HVAC trade I have seen many times where the unit has discharged back into another well, but the equipment has to have approaved exchangers that prevent the refrigerant, oil, or other contaminates from leaking into the water side of the unit. Most if not all geothermal systems now have these approaved exchangers. The exchangers are doubled walled and their is an open area on the exchanger so if there is a leak on the refrigerant side it will leak into the home and not into the water side and vice versa.
One of the main reasons water isn't returned to a rechage well is cost. It's cheaper to just dump the water than drill another well for the returning of water. If the aquafer is low on rewater recovery then another well is usually drilled so water capacity remains high when needed for living uses.
The return wells are sometimes called 'recharge' wells and other names.
Here is a paste from http://pbisotopes.ess.sunysb.edu/lig/Conferences/abstracts-03/boyce.htm
Open loop geothermal systems typically include one or more supply wells and one or more diffusion, recharge, return or injection wells. In an open loop geothermal well system, groundwater is withdrawn from an aquifer through the supply well and pumped to a heat exchange device where it acts as a heat source or sink in the heating or cooling process. A typical heat exchange device is a plate heat exchanger, in which a non-contact, non-consumptive process takes place between the groundwater and the building?s internal circulation water. Heat is transferred between the two waters without ever physically coming into contact or mixing with one another. Once the groundwater passes through the heat exchange device it is returned to the aquifer through a diffusion well(s). The only difference between the supply and return water is the temperature. The open loop system is one of the more common systems found on Long Island and is utilized in both large and small scale applications