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Siemens Building Technologies
Basic Documentation LMU54... / LMU64...
CC1P7494en
HVAC Products
7 DHW control (BWR)
07.11.2002
This output is used for switching off the external transformer. The output is active when
the external transformer is required; otherwise, it is inactive.
The objective is to switch off the external transformer as often as possible in order to
minimize the system’s overall energy consumption.
The external transformer is required for the DC 24 V fan and the 2 stepper motors.
There are thus 3 potential reasons for switching on the external transformer:
−
Fan
−
Stepper motor required for optimization of combustion
−
Stepper motor of the diverting valve (if present)
If at least one of these components calls for power, the external transformer will be
switched on.
The demand for power from the fan and the stepper motor for combustion optimization
is met in that the external transformer is always switched on when the burner control’s
operating state is any but standby.
If parameter «LmodNull» is not equal to zero, the fan mut also operate in standby, that
is, the external transformer always remains on.
This output delivers the control signal for the pump of the LMU...’s second heating
circuit. The pump of the second heating circuit is always assigned to the mixing valve
clip-in module.
If the second heating circuit is a pump circuit, the pump can also be controlled via the
programmable output .
This function is used for controlling a DHW circulating pump. It necessitates a QAA73…
of software version 1.4 or higher.
The criteria for switching on the DHW circulating pump (e.g. time switch program) are
determined by the QAA73… .
This function is used to activate the programmable output when the input for the warm
air curtain function has been set (see programmable input LMU… basic or relay clip-in
function module).
If this input is not set, the output will also be reset .
This function is used to control the pump after the pressureless header. The function is
only available with the hydraulic diagrams that, in addition to heating circuit 1 (pump
heating circuit), have no other heating circuits included.
The pump after the pressureless header will always be switched on when the LMU…
with pump Q1 serves heating circuit 1. In that case, pump Q1 supplies water to the
pressureless header.
Like pump Q1, the pump after the pressureless header features pump overrun and
pump kick).
This function is used for controlling system pump Q8 with hydraulic diagrams 67, 70, 71
and 72. Precondition is that the system pump function has been activated via parameter
«Q8Fkt» (KonfigRg4).
This function is used to activate the output for the period of time full charging of the
DHW stratification storage tank is activated.
This means that the function can only be activated when using hydraulic diagrams that
include stratification storage tanks. Otherwise, the output remains reset.
Switching off the
external transformer
Pump output second
heating circuit
DHW circulating pump
Actuating device with warm
air curtain function activated
Pump of pressureless
header
Basic function of controller
clip-in module
Actuating device with full
DHW charging activated
