Basic Documentation

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Siemens Universal controllers RMU710B, RMU720B, RMU730B CE1P3150en
Building Technologies Preheating function (basic types A, P) 03.10.2011
To calculate purge time, the design temperature ( = lowest outside temperature)
and the associated "purge time max" must be entered. The preheating function is
only started if the outside temperature lies below the adjusted "Outside
temperature limit value".
The purge time is calculated according to the following diagram, as a function of
the outside temperature:
max
min
20 °C
3140D25en
Design
temperature
Purge time
OT limit
OT
The output position during the purge time is calculated according to the following
diagram:
100 %
0 %
20 °C
3140D26en
Design
temperature
Valve position
OT
Prepurging takes place according to the following diagram:
0 %
t
w
3140D27en
Valve position
purge timepurge time
start
fans
start
preheating
controlling normal
On completion of the prepurge time and of the start delays entered for the fans, the
fans start to operate.
The preheating function is not activated when the fan is switched on via the
"Smoke extraction" function.
Proper functioning of the preheating function depends on the correct location of the
sensor. For this reason, the outside air sensor should be installed outside the
building. If that is not possible, it should be located directly by the outside air intake
in front of the outside air damper.
Function diagrams
Note