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Building Technologies
Boiler Sequence Controller RMK770
CE1P3132en
HVAC Products
6 Boiler sequence management
01.03.2005
the value set. And for every additional boiler, the accelerated performance of the inte-
gral applies. The switch-on delay is at its initial value again.
When there is a valid temperature requisition, it is always the basic stage of at least one
boiler that is released. If there is no temperature requisition, all boilers are immediately
locked.
If heat consumption drops, the boilers are switched off based on the temperature crite-
rion or output balance.
In the case of surplus output, the temperature deviation is accumulated, the same way
as with output shortage. Boilers are locked only if the main flow temperature lies above
the neutral zone about the setpoint.
To ensure that the boilers are switched off in steps, the switch-off integral is restarted
each time a boiler is shut down.
Main menu > Commissioning > Settings > …
or
Main menu > Settings >
Boiler sequence manager > Control parameters
Operating line
Range
Factory setting
Downward sequence integral
0…500 K×min
50 K×min
The switching off of a boiler can be impacted by the switch-off integral.
A small switch-off integral means that removal of a boiler from the boiler sequence is
fast.
b
50
47
53
°C
41
44
t
t
swiwtch off
TempMnFlow
TempFlowWDem
TempSeqSwitchDiff
313
2
D
0
6
TempFlowWDem
Flow temperature setpoint for performing the integral
TempSeqSwitchDiff Neutral zone (3 K)
TempMnFlow
Main flow temperature
t Time
t switch off
Time to elapse for boiler to be switched on
Switching off via the output balance prevents a large number of boilers from operating
at low output although heat demand could be covered by a smaller number of boilers.
Main menu > Commissioning > Settings > …
or
Main menu > Settings >
Boiler sequence manager > Control parameters
Operating line
Range
Factory setting
Downward sequence output limit
0…100 %
--- %
If several boilers maintain simultaneously the same setpoint – e.g. in the case of modu-
lating or 2-stage burners where the individual setpoint boost is set to 0 K or to a very
small value – the output balance is added as a second switch-off criterion.
For 20 minutes, the average boiler output of the boilers in operation must be smaller
than the downward sequence output limit. Also, to ensure that sufficient amounts of
heat can be delivered after boilers have been switched off, it is checked whether the
calculated required output of the boilers remaining in operation would amount to a
maximum of 95 %.
Switching boilers off
Switching off via the tem-
perature-time integral
Switch-off command via
output balance