Compressor Control In Plants Without Buffer Or Combi Storage Tank - Siemens RVS41.813 User Manual

Increase source prot temp
Prerun time source
Overrun time source
Time limit source temp
min

Compressor control in plants without buffer or combi storage tank

Control
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Siemens Switzerland Ltd
HVAC Products
In the case of brine-to-water heat pumps, the controller raises automatically the
minimum source temperature (2816) by the adjustable value "Increase source prot
temp" during the time the floor curing function is performed.
Before putting the compressor into operation, the source pump (or the fan in the case
of an air-to-water heat pump) must be activated, ensuring that the refrigerant passes
through the evaporator, enabling the sensors to acquire the correct temperature.
When the compressor is switched off, the source pump (or the fan in the case of an air-
to-water heat pump) continues to run for the time set here.
Source startup time max If, during the adjustable "Source startup time max", the source
temperature does not reach the required level (2815 or 2816 plus 2817), the heat pump
goes to lockout. The fault must be reset, either manually or automatically.
Refer to the description of "Source temp min water" (2815) or "Source temp min brine"
(2816).
In the event of a heat pump fault, the source pump will be deactivated until the fault is
corrected.
The parameters described above – with the exception of prerun and overrun time
source – have no impact on air-to-water heat pumps.
During "Time limit source temp min" (2822), the electric immersion heaters installed in
the flow are activated.
The settings apply to compressor 1 and – if present – to compressor 2.
If there is no buffer or combi storage tank installed, the compressor is switched
according to the return temperature (B71) and the "Switching diff return temp"
(operating line 2840).
The return temperature setpoint is used for calculating the switch-on or switch-off point.
The return temperature setpoint is calculated based on the required flow temperature
setpoint and the "Differential HC at OT –10 °C" (5801). The adjustable "Switching diff
return temp" (2840) lies symmetrically about the calculated return temperature setpoint.
T
2840
ON
K
OFF
2840 Switching differential return temperature
OFF Switch-off point
ON Switch-on point
TRLw Return temperature setpoint
K Compressors
The switch-on / off points are impacted by a number of other functions (maximum
switch-off temperature, compensation of heat deficits, compressor running time
minimum, compressor off time minimum, pump prerun time, and pump overrun time).
User manual RVS61.843, RVS41.813
6 The settings in detail
TRL
OFF
TRLw
ON
t
CE1U2355en_02
28. September 2009