Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
Using a chiller of type Heat Pump forces you to use the loop type 2-pipe as that defines whether the heat pump is in heating or cooling mode. The challenge as you have observed is that when the loop is in cooling mode it is not available for reheat.
One solution that was recommended to me was to have two 2-pipe loops -- one with forced to heating mode with heating loads on it and the other with cooling loads on it forced to cooling -- each with its own copy of the air-source heat pump chiller and with a supplementary boiler on the heating 2-pipe loop.
Notes: 1) I have found that this works when the loops are commanded to heating and cooling using Snap on Outdoor Air Temperature (very high for heating loop, very cold for cooling loop). It did not work for me when I tried scheduling the loop operation. (Not sure why.) 2) I was unable to add a heating coil to the airside system but could add a preheat coil and reheat coils. Adding a heating coil shifted the cooling load to the heating loop which results in the error that there was no load on the chilled water loop.
Thank you to Bill Bishop for this recommendation.
