The heat pump is equipped with a desuperheater which is used to heat hot water for use in the building. When the heat pump is operating (in either heating or cooling mode), a pump draws cool water from the bottom of the storage tank, passes the water across the desuperheater where it is heated, and returns the hot water to the top of the storage tank.

To calculate the effects of the desuperheater on hot water tank energy use, a water draw profile, and make-up water temperature profile are required. These profiles are input to the program through the use of the TRNSYS forcing function component.

The thermal and hydraulic losses due to the pipes leading to/from the storage tank are ignored in this simulation.