airloophvac:unitarysystem plant loop temperature control issue

asked 2018-05-03 12:28:29 -0600

elvinruya gravatar image

updated 2018-05-04 06:32:39 -0600

This issue has been discussed for years I hope someone can help me to figure this out. Unitary system cooling coils cause condenser water loop plant temperatures to get too hot and cause system to fail.

**  Fatal  ** CheckForRunawayPlantTemps: Simulation terminated because of run away plant temperatures, too hot

As it was discussed earlier not to have multiple objects in unitary object here is my current setup for the unitary system object:

  • only consists of Coil:Cooling:WaterToAirHeatPump:EquationFit
  • fan is modeled separately downstream of the unitary object
  • mixed air setpoint manager is added for the unitary object
  • condenser water plant loop has a constant speed pump which has a continuous control type as intermittent control

The pump outlet temperature is causing the fatal error. I tried adding outdoor air pipe to the supply branch outlet node, adding bypass branch to the supply loop or changing setpoint manager types for the unitary object but nothing could solve this issue. I will appreciate any feedback.

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