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Building Technologies Boiler Sequence Controller RMK770 CE1P3132en
HVAC Products 7 Boiler control 23.04.2009
If the switch-off point is reached before the minimum burner running time is completed,
the burner remains in operation until that time has elapsed (burner cycling protection).
The minimum burner running time is given priority. The burner’s switch-off point is
raised by half the boiler’s switching differential. If, within the minimum burner running
time, the boiler temperature exceeds the setpoint by more than 1 switching differential,
the burner is shut down even if the minimum burner running time has not yet elapsed.
On completion of the minimum burner running time, the burner’s switch-off point is set
to the boiler’s setpoint plus one half switching differential.
0
1
0
1
TBo
t
BuRuntMin
Bu
3133D10
TBoSetpt + SDBo
TBoSetpt +
1
/
2
SDBo
TBoSetpt
TBoSetpt -
1
/
2
SDBo
BuRuntMin BuRuntMin
BuRuntMin
TBo
Bu Burner
BuRuntMin Minimum burner running time
SDBo Boiler switching differential
t Time
Tbo Boiler temperature
TboSetpt Boiler temperature setpoint
7.8.2 2-position control of 2-stage burners
Main menu > Commissioning > Settings > … or
Main menu > Settings > Boiler … > Burner
Operating line Range Factory setting
Release limit stage 2 0…500 K×m 50 K×m
Reset limit stage 2 0…500 K×m 10 K×m
Locking time stage 2 0…60 min 10 min
7.8.3 Control of burner’s basic stage and stage 2
This subsection describes the switching logic of the basic stage and the release and
reset criteria for 2-stage burner operation.
As long as stage 2 is locked, the basic stage operates like a 1-stage burner.
As long as stage 2 is released, the calculated switch-on and switch-off points for stage
2 apply.
Exception: The second burner stage is switched off as soon as the boiler temperature
has risen to a level where the differential to the maximum boiler temperature represents
the setting value “Delta boil temp max“ (refer to subsection 7.9.10 “Protection against
pressure shocks”). If the maximum boiler temperature is exceeded, the basic stage is
also switched off and stage 2 locked.
Minimum burner running
time, burner cycling
protection
Basic stage
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