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Siemens Building Technologies
Basic Documentation RVA47.320
CE1P2379E
HVAC Products
Description of the OEM settings
15.07.2002
6.4.2
Running time strategies
The running time strategy defines the criteria for the switching on / off of the lag boilers.
It is determined by the following parameters:
- Nominal output of BMU 1 - 4
See line 91 -94
- Entry of minimum limit of output range (Pmin)
See line 10
OEM
- Entry of maximum limit of output range (Pmax)
See line 52
OEM
The RVA47.320 initiates changeover only when it leads to a valid operational status
while taking the above parameters into consideration.
The following parameters also have an impact on the function:
- Delayed switching on of BMU
see line 133
- Restart lock for BMU
see line 134
For stability reasons, each BMU added to the cascade first runs on the basic stage for
about one minute on completion of which it will be released for modulating control to
deliver the output required.
The running time strategies described below become active only when the flow
temperature setpoint is reached. During the heating up time (e.g. after night setback),
the boilers required are run up to the maximum released output as quickly as possible
(short heating up time).
Additional boilers are switched on as late as possible and switched off again as early as
possible. Hence, the aim is to have the
smallest possible number of boilers in
operation
, or to obtain short running times for additional boilers.
2379Z05a
ON
ON
53%
53%
53%
80%
40%
40%
80%
80%
80%
80%
80%
100%
100%
100%
53%
53%
53%
40%
40%
OFF
80%
80%
OFF
80%
80%
80%
80%
P
= increase in output
= Switching onZuschaltung
= decrease in output
= Switching offWegschaltung
P
= OutputLeistung
General
Notes
Important
Strategy 1:
Example of three boilers
with an output range of 20
- 80 %:
