For me its not clear why it is not common to drop closed loop temperature below 32F (because equipment efficiency or something else) and how closed loop length depends on it?
Yes the length of the loop and the building load will dictate how low the temperature of the ground will drop. We generally design the loop based on the load and length so that the loop does not commonly drop below 32F/0C (freezing). As the temperature of the loop drops the output and efficiency of any Geothermal System will drop accordingly. For example, if a loop drops from 10C to 0C over the winter the output of the system will drop approximately 19% and the efficiency will drop by approximately 10%. But, remember that the warmer the ground temperature the better in the winter but the opposite is true in the summer. Normally the winter and summer ground temperatures will work to encourage the best operating temperatures provided that the system has been sized correctly, considering summer and winter. Also, the longer the loop the more ground it has to take heat out of, and to reject heat to, so again “the longer the loop the better”.
Related Questions
- For me its not clear why it is not common to drop closed loop temperature below 32F (because equipment efficiency or something else) and how closed loop length depends on it?
- What can the minimal temperature of the closed loop drop to (32F or less)?
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