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Building Technologies
Modular Heating Controller RMH760B
CE1P3133en
HVAC Products
6 Boiler temperature control
05.02.2007
If the switch-off point is reached before the minimum burner running time has elapsed,
the burner will continue to operate until that time is completed (burner cycling protec-
tion). The minimum burner running time is given priority.
The burner’s switch-off point will be raised by half the boiler’s switching differential. If,
within the minimum burner running time, the boiler temperature exceeds the setpoint by
more than the full switching differential, the burner will be shut down although the
minimum burner running time has not yet elapsed. On completion of the minimum
burner running time, the burner’s switch-off point will be set to the boiler temperature
setpoint plus half the switching differential.
0
1
0
1
TBo
t
BuRuntMin
Bu
31
33
D
10
TB SDBo
TB
1
/
2
SDBo
TBoSetpt
TBoSetpt -
1
/
2
SDBo
BuRuntMin
BuRuntMin
BuRuntMin
TBo
Bu Burner
BuRuntMin
Minimum burner running time
SDBo
Boiler’s switching differential
t
Time
TBo Boiler
temperature
TBoSetpt
Boiler temperature setpoint
6.5.2 2-position
control with 2-stage burner
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
6.5.3 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 soon as stage 2 is released, the calculated switch-on and switch-off points for stage
2 apply.
Exception:
The second burner stage will be switched off as soon as the actual boiler
temperature has risen to a level lying the setting value
Delta boiler max (stage 2)
below the
maximum boiler temperature (refer to subsection 6.6.12 “Protection against pressure
shocks”. If the maximum boiler temperature is exceeded, the basic stage will also be
switched off and stage 2 locked.
Minimum burner running
time, burner cycling
protection
Basic stage