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Building Technologies
Modular Heating Controller RMH760B
CE1P3133en
HVAC Products
6 Boiler temperature control
05.02.2007
31
33
S
72
TBo
ByPu
TRtBo
The bypass pump can be controlled either according to the acquired return temperature
or, when there is no sensor, parallel to burner operation.
Normally, the return temperature sensor is installed upstream of the bypass pump (on
the consumer side) to avoid too frequent switching of the bypass pump.
Main menu > Commissioning > Settings > …
or
Main menu > Settings > Boiler > Limitations
Operating line
Range
Factory setting
Bypass pump switching diff
0…20 K
6 K
The return temperature is controlled with the bypass pump in 2-position mode within
the adjustable switching differential.
The pump will be activated when there is demand for heat and when the return tem-
perature drops below its minimum limit value.
The pump will be deactivated when the return temperature exceeds its minimum limit
value by the switching differential, or when there is no demand for heat.
Br
ByP
TiOverrunCnsm
TBoR
t [min]
10
20
30
60
50
40
30
SDByP
TBo
TBoRmin
0
1
t
0
1
t
313
1D
05
Br Burner
ByP Bypass
pump
SDByP
Switching differential of bypass pump
t
Time
TBo
Boiler temperature
TBoR Boiler
return
temperature
TBoRmin
Minimum limit value of the boiler return temperature
TiOverrunCnsm Consumer overrun time
After the burner has been shut down, pump overrun (refer to section 5.4 “Pump overrun
and mixing valve overrun”) also acts on the bypass pump.
In addition to activating the bypass pump, locking signals are generated if required and
when a return temperature sensor is connected. If this is not required, setting “None“ can
be selected for “Lock sig maintained boil ret temp”.
If no return temperature is available, the bypass pump will be controlled parallel to
burner operation. The bypass pump always runs when released and when the basic
burner stage is on.
When using a boiler with mixing valve in the boiler return (plant type H4-x), maintained
boiler return temperature will be ensured by the separate mixing valve.
Control of the bypass
pump parallel to burner
operation
Maintained boiler return
temperature controlled
by mixing valve