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Building Technologies Division User Manual LMS14… CC1U7471en
6 The settings in detail 28.01.2015
6.12.10 Protective boiler startup
Below the boiler’s minimum temperature, protective boiler startup ensures that the
boiler is heated up more quickly by shutting down or reducing loads, depending on the
hydraulic choices available.
To exert influence on the consumers, a so-called locking signal is generated to which
the consumers can gradually respond. The consumers’ response can be parameterized
via Prot boil startup consumers (2260).
When the burner is switched on and the boiler temperature lies below the minimum
(cold start), or drops below it within a predictable period of time (warm start), the locking
signal increases.
If the current boiler temperature lies above the minimum, or reaches this level within a
predictable period of time, the locking signal becomes smaller.
If the boiler temperature remains constantly in the range between the minimum boiler
temperature and half a boiler switching differential below that level, or will reach this
range after a predictable period of time, the locking signal is maintained.
Note!
To ensure that the minimum boiler temperature can be reliably reached, the neutral
zone within the parameterized integral action time from the boiler temperature’s
turning point is reduced from half the boiler’s switching differential to zero. Next time
the burner is switched on, the new start will be made with half the boiler’s switching
differential.
To ensure that this dynamic behavior is made possible, a virtual boiler temperature is
calculated. This virtual boiler temperature is composed of the current boiler temperature
and the current boiler gradient, amplified by the anticipation time. The anticipation time
required for calculating the virtual boiler temperature can be set.
Virtual boiler temperature = current boiler temperature + (TKgradient * Tvoraus)
The locking signal has a value range from 0% upto 100%.
The switching differential (SDK) used is the Switching diff on HCs (2454) or Switching
diff on DHW (2460) respectively, in accordance with the source of the current request
for heat (heating circuit or DHW).
Calculation of locking
signal
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