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Building Technologies
Boiler sequence controller RMK770
CE1P3132en
HVAC Products
6 Boiler sequence management
23.04.2009
6.3
Boiler sequence management
6.3.1 Concept
T
T
T
T
T
MnPu_A
TMnRt
TMnFl
MnVlvRtMx
TRtMx
TBo
T
TRtCo
MnPu_B
T
TBo
1
2
TFl
w
TFl
x
TBo2
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TBo1
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S60
With the signal received from the main flow temperature sensor, the boiler sequence
manager controls the individual boilers or burner stages of the boiler sequence. It
decides on the release of a boiler, predefines the boiler temperature setpoint for the
boilers released and, in addition, releases the individual burner stages depending on
heat demand.
Here, the boiler sequence manager differentiates between lead boiler and lag boilers.
The lead boiler is always the first boiler to be put into operation. It always maintains the
boiler temperature setpoint predefined by the boiler sequence manager. The boiler
temperature setpoint of the lead boiler is raised or lowered, depending on the deviation
of the temperature acquired by the main flow sensor from the setpoint. The setpoint
correction can be adjusted.
Main menu > Commissioning > Settings > …
or
Main menu > Settings >
Boiler sequence manager > Control parameters
Operating line
Range
Factory setting
Boiler setpoint boost max
0…100 K
10 K
An increase can be applied to the boiler temperature setpoint of the lag boilers.
Main menu > Commissioning > Settings > …
or
Main menu > Settings >
Boiler … > Operation settings
Operating line
Range
Factory setting
Setpoint increase lag boiler
0…50 K
10 K
A considerable increase of the boiler temperature setpoint ensures that the lead boiler
provides control and that the relevant lag boiler operates at full capacity. This approach
prevents several boilers with their burner stages from cycling simultaneously.
When using a small increase or no increase at all, the relevant lag boiler also operates
in control mode. This can be desirable in the case of boiler sequences with several
modulating burners.
Control of the burner, boiler pump and actuating devices is ensured by the individual
“Boiler“ function blocks.
The boiler sequence manager releases the boilers in a stepwise fashion; first the basic
stage and then the second stage or modulation.
Setting
Setting