Summary:
I'm encountering an unexpected problem while attempting to model advanced dehumidification via heat recovery using the UnitarySystem. Specifically, the heating coil fails to activate, leading to an uncontrolled zone temperature during the heating season.
Details:
My objective is to model a system capable of regulating both temperature and relative humidity in a specific zone with notable latent loads. Here's the expected behavior:
- When the zone thermostat requires heating or cooling, the
UnitarySystem's heating or cooling coil should provide the necessary energy to restore the zone temperature to the desired range. - If the zone's relative humidity surpasses a defined threshold, the cooling coil should lower the air temperature beyond the dew point for optimal dehumidification. Subsequently, the reheat coil should elevate the temperature back to the thermostat's set range.
Under normal conditions, when the system isn't dehumidifying, the reheat coil should remain inactive. Additionally, the cooling coil's condenser heat should be dissipated outdoors through the dry cooler (FluidCooler:TwoSpeed).
These are the 3 type of coils I'm using:
- Cooling coil:
Coil:Cooling:WaterToAirHeatPump:VariableSpeedEquationFit - Reheat coil:
Coil:Heating:Water(powered by heat recovered from the cooling coil's condenser, water side) - Heating coil:
Coil:Heating:Electric
I've set up two plant loops: one for the reheat coil/condenser loop and another for the condenser/dry cooler loop. These loops are interconnected via an ideal heat exchanger.
The simulation completes without severe errors in the Chicago climate (USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.epw). However, the zone temperature isn't being adequately controlled. The heating coil remains inactive even when the zone temperature falls well below the setpoint. Moreover, the system seems to initiate dehumidification only starting from mid-April. Meanwhile, the reheat coil appears to elevate the temperature significantly above the cooling setpoints.
Could someone examine the IDF attached to this link to identify the potential cause of this behavior? I've attempted adjustments to the Latent Load Control and Setpoint Manager types governing the UnitarySystem outlet node temperature but haven't achieved success.
Any guidance on resolving this issue would be greatly appreciated.
