Heat Pump Water to Water Controls

edit

I am trying to model a chiller plant for a building with heat recovery chillers and air cooled chiller. The heat recovery chillers (water to water heat pumps in OS) need to turn on first on the cooling side but regulate to the heating demand.

In Summer months when more cooling is required the hot water loop overheats from the heat recovery chiller dumping too much heat into the loop. Error is shown below. Does anyone have a suggested work around to this issue?

   **  Fatal  ** CheckForRunawayPlantTemps: Simulation terminated because of run away plant temperatures, too hot
   ...Summary of Errors that led to program termination:
   ..... Reference severe error count=1
   ..... Last severe error=Plant temperatures are getting far too hot, check controls and relative loads and capacities