How to Decide Between Open-Loop Vs. Closed-Loop Geothermal Heat Pump Systems

Wednesday, December 9, 2009: 3:00 p.m.
Todd Giddings, Ph.D., PG , Todd Giddings and Associates Inc., State College, PA
     The decision process to follow when you are asked recommend an open-loop vs. a closed-loop geothermal heat pump system for a given site and building involves much more than just recommending a closed-loop system and saying “closed-loop systems don’t have issues with precipitating minerals in the well water”.  What if the site owner has a high-yield well with good groundwater quality?  The cost of the loop field may cause the owner to not go geo at all. 

     This presentation will go step-by-step through a decision tree diagram to show how well yield, groundwater quality, drilling conditions, space to install a loop field, thermal conductivity of the bedrock, maintaining the hydrologic balance, and environmental sensitivities of the site can all be evaluated in sequence to arrive at the best recommendation for a given site location and building.  Examples of closed-loop and open-loop geothermal systems (including standing-column well open-loop systems) will be presented and discussed.

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