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Building Technologies Division User Manual LMS14... CC1U7471en
6 The settings in detail 07.05.2014
The following assignments apply, depending on the operating mode:
Heating mode DHW storage
mode
Instantaneous water
heater mode
Minimum switch-off differential 2455 2461 2461
Maximum switch-off differential 2456 2462 2462
Switch-off differential SdAus f (heating circuit) f (DHW) f (DHW)
Switch-on differential SdEin 2454 2460 2460
Time to reduction to minimum switch-off
differential
2457 2463 2463
Key
Line no. Meaning
2454 SdHkEin Switch-on differential heating circuits
2455 SdHkAusMin Minimum switch-off differential heating circuits
2456 SdHkAusMax Maximum switch-off differential heating circuits
2457 ZsdHkEnde Settling time heating circuits
2460 SdTwwEin Switch-on differential DHW
2461 SdTwwAusMin Minimum switch-off differential DHW
2462 SdTwwAusMax Maximum switch-off differential DHW
2463 ZsdTwwEnde Settling time DHW
f Function of
By equating the switching differentials (2455 = 2456 or 2461 = 2462), the dynamic
switch-off differential can be deactivated. In that case, the switching differentials are still
dynamically calculated, but – due to limitation of the switching threshold – the result
obtained is always the value parameterized for the switch-off differential.
In addition to limiting the switch-off thresholds, it is made certain that a minimum
switching differential of 2 K is observed. If switch-on and switch-off thresholds have a
smaller temperature difference, the switch-on threshold is forced to a reduced level of
(switch-off threshold boiler –2 K). In that case, no consideration is given to minimum
limitations.
For better illustration, an example is given here:
2210 = 40 °C 2454 = 1 °C SkHkAus = 0 °C 8311 = 40 °C
Based on these temperatures, the following thresholds are calculated:
Switch-off threshold boiler = 8311 + SdHkAus = 40 °C + 0 °C = 40 °C
Switch-on threshold boiler = 8311 - 2454 = 40 °C - 1 °C = 39 °C
The difference of (switch-off threshold boiler – switch-on threshold boiler) is only 1 °C.
This means that the minimum switching differential is not observed. For this reason, the
switch-on threshold is lowered:
Switch-on threshold boiler = switch-off threshold boiler - 2 °C = 40 °C - 2 °C = 38 °C
Key
Line no. Meaning
2210 Setpoint minimum
2454 SdHkEin Switch-on differential heating circuits
8311 TKSoll Boiler temperature setpoint
SdHkAus Switch-off differential heating circuits
Note!
The dynamic switching differentials can only be parameterized with positive values.
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