Ground Loop combined with boiler and cooling tower, temperatures too hot

asked 2020-07-23 13:42:44 -0500

Abarker gravatar image

updated 2020-07-23 13:59:46 -0500

I'm trying to model a GroundHeatExchanger:System coupled with a boiler and cooling tower for peak heat addition / rejection to a mixed water loop. My mixed water loop is a PlantLoop, not a CondenserLoop, and serves distributed heat pump coils.

My approach has been to use HVAC Template objects to set up distributed heat pumps connected to a mixed water loop with boiler and cooling tower, then expand that file and splice in the GLHE objects. Everything seems to be connected properly, however the simulation terminates with a fatal error partway through as plant temperatures are getting too hot (+300degC).

The GroundHeatExchanger:System was added to my PlantEquipmentList for both heating and cooling operation, given priority over the boiler and cooling tower. I have a dual setpoint manager for the loop, where the Demand Calculation Scheme is set to DualSetPointDeadband

Is there an inherent issue with combining a GLHE with a boiler or cooling tower, or by adding it to a PlantLoop rather than a CondenserLoop? (the later has worked in the past for me, but not with the boiler and cooling tower added as well)

Is there a sample file out there with this situation that works? All example files I have found describe a GLHE on a Condenser loop serving a water to water heat pump, which I haven't found helpful for this situation.

I'm fairly sure the size of the borehole field is not the issue, as doubling or halving the size does not change the outcome.

Thanks in advance for any help.

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