Basic Documentation

70/256
Siemens Modular Heating Controller RMH760B CE1P3133en
Building Technologies 6 Boiler temperature control 2017-09-29
During test mode, fault status message Boiler test operation active is displayed. It is
maintained until preselection "Test mode" is set back to "Auto". This is to make certain
that the plant will not be quit without ending the test mode.
In the "Auto" position, the boiler is released and the test mode deactivated.
The boiler will be switched off, that is, the burner will be shut down and the pumps
deactivated.
The boiler is released. The aggregates (shutoff valve, maintained boiler return
temperature with mixing valve, and boiler pump) are active, but the burner is still off.
The boiler is released and the burner with its stage 1 or the basic stage maintains the
adjusted test mode setpoint.
The boiler is released and the burner with its stages 1 and 2 or the basic stage and
modulating part maintains the adjusted test mode setpoint.
The boiler is released and the modulating burner runs to the modulation level according
to the setting made. The burner will be switched off when the maximum boiler
temperature limit value is exceeded.
6.5.1 2-position control with 1-stage burner
Adjustable variables for 2-position control with a 1-stage burner:
• Boiler’s switching differential
• Minimum burner running time
Main menu > Commissioning > Settings > … or
Main menu > Settings > Boiler > Burner
Operating line
Range
Factory setting
Boiler switching differential
1…20 K
6 K
Burner run time min
0…60 min
4 min
The controller compares the actual value of the boiler temperature with the setpoint. If
the boiler temperature falls below the setpoint by half the switching differential, the
burner will be switched on. If the boiler temperature exceeds the setpoint by half the
switching differential, the burner will be switched off.
TBoSetpt +
1
/
2
SDBo
0
1
3131D03
TBo
TBoSetpt
TBo
t
Y
B
TBoSetpt -
1
/
2
SDBo
SDBo
Boiler’s switching differential
t
Time
TBo
Boiler temperature
TBoSetpt
Boiler temperature setpoint
Y
B
Burner control signal
Auto
Boiler off
Pump on (burner off)
Stage 1 controlled
Stages 1 + 2 controlled
Modulating, fixed
Settings
Switching differential