Siemens RVS41.813 User Manual page 123

Reset integral stage 2
Compr sequence
changeover
Siemens Switzerland Ltd
HVAC Products
Setpoint not reached on time:
T
Tx
SD
Tw
2862
1
S1
0
1
S2
0
TW Flow or return temperature setpoint
Tx Actual value of flow or return temperature
SD Switching differential
S1 Compressor stage 1
S2 Compressor stage 2
2862 Locking time stage 2
2863 Release integral stage 2
T Temperature
t Time
In the case of flow temperature control, the controller uses the flow temperature for
calculating the release and the reset integral. When control is based on the return, the
return temperature is used for making the calculation.
To ensure correct switching on of the second stage with storage tank charging (buffer
or DHW storage tank), a flow temperature sensor must be connected. If that sensor is
missing, the controller makes the calculation with a backup value of 0 °C.
If there is excess heat, the controller generates an integral. As soon as the set value for
the integral is reached, release of the second stage is withdrawn and the first stage
switched off. If the temperature returns to a level below the switch-on point, the first
compressor is switched on again.
T Tx
2864
SD
Tw
1
S1
0
1
S2
0
If both stages together deliver too much heat, the second stage is immediately switched
off when the switch-off point or, latest, the reduced maximum switch-off temperature is
reached (2844 and 2845).
Automatic changeover of the compressors ensures that both compressors operate
pretty much the same number of hours.
If the difference of operating hours between the first and the second compressor
exceeds the limit (h) set here, the order of startup changes as soon as both
compressors are switched off. This means that compressor 1 becomes compressor 2,
and vice versa. The current compressor sequence appears on operating line 8446.
User manual RVS61.843, RVS41.813
6 The settings in detail
Setpoint reached on time:
T
2863
2862 2862
t
TW
Tx
temperature
SD
S1
S2
2864 Reset integral stage 2
T
t
t
2862
Flow or return temperature setpoint
Actual value of flow or return
Switching differential
Heat pump stage 1
Heat pump stage 2
Temperature
Time
CE1U2355en_02
28. September 2009
t
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