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Pump control
Pump control with
pump circuits
Pump control with
mixing circuits
Pump overrun
Pump kick
Mixing valve control
Position of mixing valve
in the idle state
Functional test
Siemens Building Technologies
HVAC Products
The pump is controlled via the mixing valve clip-in module. This also applies to pump
overrun and the pump kick.
In the case of a mixing circuit, the pump can also be activated by the mixing valve clip-in
module, independent of the LMU... (e.g. during frost protection for the heating circuit).
During pump overrun, the controller is also active. It maintains the flow temperature
setpoint that was valid prior to pump overrun. On completion of the pump overrun in the
case of mixing circuits, the mixing valve will be driven to the fully closed position.
After the pump kick in the case of mixing circuits, a kick is given to the mixing valve
actuator (pump is deactivated). The mixing valve will then be driven toward the fully
open and then toward the fully closed position.
The time of control toward the fully open position corresponds to the parameterized
actuator running time, and an additional 10 seconds toward the fully closed position.
The mixing valve clip-in module is suited for mixing valves equipped with a 3-position
actuator. This necessitates 3 states for the control of the mixing valve:
• Toward fully open
• Toward fully closed
• Unchanged
The running time of the mixing valve is to be parameterized on the LMU...
This actuator running time will be used for both the opening and the closing command
(symmetric actuator).
If, in the case of a system with mixing circuit, the controller of the mixing valve clip-in
module is not active - which means no pump control by the LMU... either (with the
exception of the pump kick) - the mixing valve will be driven to the fully closed position.
The duration of control depends on the paramererized actuator running tiem and is as
follows:
2 x actuator running time
After each reset, the mixing valve clip-in module automatically makes a functional test.
In the test, the mixing valve is first driven toward the fully open position (8 seconds) and
then toward the fully closed position (10 seconds).
Then, the output is used for the control of the pump (10 seconds).
Basic Documentation LMU54... / LMU64...
4 Clip-in AGU2.500... for additional heating circuit
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CC1P7494en
07.11.2002
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