Heat Pump Protection During Dhw Charging - Siemens RVS41.813 User Manual

Number : DHW charging
attempts
128/258
Siemens Switzerland Ltd
HVAC Products
In the following situations, the integral is set to 0:
•
No valid temperature request delivered
•
Setpoint change > 2 K
•
Frost protection for the HP is active
•
The heat pump has gone to lockout or cannot deliver any heat for a longer
period of time
•
The heat pump is in active cooling mode
•
A buffer storage tank is being charged
•
The function is deactivated.
With active DHW charging, the integral value is frozen in.
In the following example of compensation, excess heat occurs during the minimum
compressor on time. Excess heat is reduced again on completion of the set minimum
compressor off time in that the compressor will not yet be released:
T
T x
VL/RL
T w
VL/RL
1
WP
0
T x Actual value of flow or return temperature
VL / RL
T w Flow or return temperature setpoint
VL / RL
2842 Compressor run time min
2843 Compressor off time minimum
WP Heat pump switching state: 0 = off, 1 = on
Comp Compensation of excess heat resulting from on time
This number determines how many times DHW charging or forced buffer storage tank
charging may be aborted until either the electric immersion heater in the flow or that in
the DHW storage tank completes the charging process.

Heat pump protection during DHW charging

The heat pump switches off, when the high-pressure switch response during DHW
charging or because the hot-gas or flow temperature approaches its maximum value.
Parameter "Number DHW charg attempts" (parameter 2893) is used to select whether
charging is aborted immediately or whether the heat pump makes a certain number of
charging attempts. In the case of several attempts, the heat pump starts the next
charging attempt each time the minimum off time (parameter 2843) has elapsed.
If the heat pump shall make only one charging attempt or if, after the selected number
of attempts, the DHW has still not reached the required temperature, DHW charging will
be aborted, the controller will save the current DHW temperature and readjust the
switch-on point to DHW temperature minus the switching differential DHW. With
diagnostics, the saved temperature appears as "Curr DHW charg temp HP" (parameter
7093). The value is maintained until – due to limitation – the heat pump must again
abort DHW charging.
If the "Curr DHW charg temp HP" lies below the adjustable value of "DHW charg temp
HP min" (parameter 7092) a maintenance message appears.
If the reduced setpoint lies below "DHW charg temp HP min" and the heat pump can
terminate DHW charging, the controller will not generate a service message.
User manual RVS61.843, RVS41.813
6 The settings in detail
2842 2843
Comp
t
CE1U2355en_02
28. September 2009