User Manual

Sequence of Operation
Ambient Heat Pump Lockouts
15
Siemens Industry, Inc.
Application Note, App 14901
140-1230
2020-02-11
Figure 3: Reversing Valve Operation.
Ambient Heat Pump Lockouts
The Ambient Heat Pump Lockout function can determine the appropriate heating
source to be enabled to optimize safety protection and heating efficiency.
An outdoor temperature sensor is required to proceed with this function. The Ambient
Heat Pump Lockout function is disabled if an outdoor temperature sensor is
unavailable or has failed.
The outdoor temperature sensor can be either a physically installed thermistor or
voltage input, or a network sensor. The RDY2000BN supports controlling to sensor
input over the network. For example, you can take one of the universal inputs,
characterize it as a voltage input, remove it from service, and expose it to the network
as writeable. Then, you can assign the value of another sensor over the network to this
input.
● Heat Pump Compressor Lockout Temperature:
The Heat Pump compressor will not operate if the OutDoorTmp is below the Heat
Pump Compressor Lockout SP (this forces the unit to auxiliary heat only). An
outdoor temperature sensor is required.
● Heat Pump Auxiliary Heat Lockout Temperature:
Heat Pump Auxiliary Heat will not operate if the outdoor temperature is above the
Heat Pump Auxiliary Heat Lockout SP. An outdoor temperature sensor is required.
● When the outdoor temperature is:
– Below HP Compressor Lockout SP: only Auxiliary Heat operates.
– Above HP Aux Heat Lockout SP: only the Compressor operates
– Between the two SPs: both the Compressor and Auxiliary Heat operate.