User Manual

Sequence of Operation
Operation Diagram - Heat Pump with Electrical Auxiliary Heater
14
Siemens Industry, Inc.
Application Note, App 14901
140-1230
2020-02-11
Operation Diagram - Heat Pump with Electrical Auxiliary
Heater
Figure 2: Heat Pump with Electrical Auxiliary Heater.
Reversing Valve Operation
The status of REV VALVE determines the operation of the heat pump’s compressors
(heating or cooling). The Reversing Valve changes from heating to cooling when the
following conditions have been met:
● The Reversing Valve is de-energized when the unit is in OFF mode.
● If O/B is selected to Heating Activated, the Reversing Valve must be energized RV
INTERVAL (default 10 seconds) ahead of the compressor being energized in
Heating Mode, and must be de-energized RV INTERVAL (default 10 seconds)
ahead of the compressor being energized in Cooling Mode. The Reversing Valve
must be energized when IndoorTmpEff drops below HeatingSp and must be de-
energized when IndoorTmpEff rises above CoolingSp.
● If O/B is selected to Cooling Activated, the Reversing Valve must be energized RV
INTERVAL (default 5 second) ahead of the compressor being energized in Cooling
Mode, and must be de-energized RV INTERVAL (default 5 seconds) ahead of the
compressor being energized in Heating Mode. The Reversing Valve must be
energized when IndoorTmpEff rises above CoolingSp, and must be de-energized
when IndoorTmpEff drops below HeatingSp.