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Siemens Building Technologies
HVAC Products
If the room temperature falls below the adjusted setpoint for frost protection, the con-
troller will activate the heating circuit pump and control the flow temperature such that
the relevant room temperature will lie above that setpoint by the amount of the switch-
ing differential of 1 K. This is ensured provided the heating curve slope is correctly set.
Without the room temperature sensor, frost protection for the building has no priority
over the ECO function.
12.11 Protective functions
This subsection covers functions that act on several function blocks.
12.11.1 Pump kick
The pump kick prevents the pumps from seizing.
The pump kick can be deactivated on operating line 146. If activated, it acts in every
operating mode. It is also performed when the heating circuit is in standby.
The pump kick function is activated for 30 seconds every Friday morning at 10:00.
If several pumps must be kicked, they are activated one after the other in the order Q1,
Q2, Q3, Q4 and K6. The kicks are separated by pauses of 30 seconds. If, with the se-
lected plant type, a certain pump is not present, the relevant kick will be omitted.
The pump kick can also be interrupted by heat source- or consumer-dependent signals.
In the case of plant types with a common flow and a pump heating circuit, pump Q1 will
not be kicked when d.h.w. is heated or when the respective pump overrun is still in pro-
gress. The pump kick will not be carried out later.
12.11.2 Valve kick
The valve kick function is activated every Friday after the pump kick.
The control outputs for the mixing valve actuators in the secondary circuits (heating
circuits, d.h.w. circuit) are activated for 30 seconds one after the other, that is, the mix-
ing valve will open. The control system will then deliver the closing command. The kicks
are separated by pauses of 30 seconds.
When there is a demand for heat and the mixing valve is "busy", there will be no valve
kick.
2-port valves in the primary circuits are not kicked.
12.11.3 Shutdown of pump
Pump shut-down serves as overtemperature protection and acts separately on both heat-
ing circuits. The function is activated when, for the heating circuit, a maximum limit value
for the flow temperature has been entered (operating line 95).
If the flow temperature exceeds the maximum limit value for the flow temperature by
7.5 °C, the pump in the heating circuit flow will be shut down. It starts running again
after the flow temperature has dropped below the limit value.
Shutdown of the pump is not a safety function!
12.11.4 Pump and mixing valve overrun
If, during overrun, there is a sudden reduction of the demand for heat, the heat con-
verter generates a forced signal to avoid the accumulation of heat. In segment 0, it is
passed to all devices in all segments; in segments 1...14, to all devices in the own
segment.
Consumers (heating circuits, d.h.w. circuits) and heat converters respond to forced
signals during overrun (bus or / and internally) as follows:
Basic documentation RVD240
12 Function block Space heating
CE1P2384en
27.05.2004
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