Heat Recovery - Danfoss AK-PC 772A User Manual

Heat recovery

The heat recovery function can be used on the installation
when you want to make use of warm gas for heating purposes.
When the function is activated the reference for the condenser
temperature will be raised to a set value. If the controller must
also activate a pump and/or a valve, a relay must be selected
for the function.
The regulation of the heat recovery circuits is done with regard
to the cooling system. In the event of conflict, the safety situation
is that the cooling system has higher priority than the recovery
circuits.
There must be a cooling requirement in order to supply for heat
recovery.
The function can be activated in two ways:
1. A digital input signal is received
In this instance, the heat recovery function is activated via
an external signal from, for example a building management
system. When the function is activated the reference for the
condenser temperature will be raised to a set value and the
attached relay outlet is used to activate valve and pump.
Pc ref
DI
2. Use of a thermostat for the function.
This function can be used with advantage where the heat
recovery is used to warm up a water tank. A temperature sensor
is used to activate/deactivate the heat recovery function. When
the temperature sensor becomes lower than the set cut in limit,
the heat recovery function is activated and the reference for
the condenser temperature will be raised to a set value and
simultaneously the chosen relay outlet is used to activate the
valve which leads the warm gas through the heat exchanger in
the water tank. When the temperature in the tank has reached
the set value, the heat recovery is cut-out again.
In both cases it applies that when the heat recovery function is
de-activated, the reference for the condensing temperature will
then decline slowly.
102
Heat recovery
Capacity controller RS8HF102 © Danfoss 2017-07 AK-PC 772A