Basic Documentation

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Siemens Modular Heating Controller RMH760B CE1P3133en
Building Technologies 5 General functions, fundamentals 2017-09-29
5.6.2 Load control
Load control enables heat generation to reduce the amount of heat drawn by the heat
consumers (load reduction via locking signals), or to increase it (load increase via
forced signals).
In the case of load control via locking signals, a differentiation is made between critical
and uncritical locking signals.
In the case of forced signals also, a distinction is made between critical and uncritical
signals.
These differentiations allow the heat consumers to respond to load control in different
ways.
Examples where a load reduction can be triggered are:
• Protective boiler startup (boiler temperature is still below the minimum boiler
temperature):
⇒
Load reduction via critical locking signals
• Maintained boiler return temperature without separate mixing valve (acting on the
heating circuits):
⇒
Load reduction via critical or uncritical locking signals
The type of locking signals to be generated can be parameterized
• Shifting DHW priority (if the boiler temperature setpoint is not reached during DHW
heating, the amount of heat drawn by the heating circuits will be restricted):
⇒
Load reduction via uncritical locking signals
• Absolute DHW priority (DHW heating is given priority over the heating circuits; the
heating circuits will not be allowed to draw any heat):
⇒
Load reduction via uncritical locking signals
An example where load increase is called for is overtemperature protection (pump
overrun, mixing valve overrun).
With pump / mixing valve overrun, the heat consumers are requested to draw heat at
the same level for a certain period of time (overrun time) although they do not demand
more heat. Overrun is typically triggered by a boiler after the burner has been shut
down in order to prevent overtemperatures in the boiler.
On the heat consumers, it can be selected if and to what extent they shall respond to
the different load control signals.
Heating circuits and DHW circuits always respond to critical locking signals. DHW
circuits never respond to uncritical locking signals.
Main menu > Commissioning > Settings > … or
Main menu > Settings > Heating circuit 1 (or 2 or 3) > Mixing circuit controller
Operating line
Range
Factory setting
Response uncrit locking signals
Yes / No
Yes
Locking signal gain*
0…200 %
100 %
Main menu > Commissioning > Settings > … or
Main menu > Settings > DHW > Controller primary circuit
Main menu > Settings > Main controller > Mixing circuit controller
Main menu > Settings > Primary controller > Mixing circuit controller
Operating line
Range
Factory setting
Locking signal gain*
0…200 %
100 %
* Locking signal gain applies to both critical and uncritical locking signals
Examples of load
reduction
Example of load increase
Heating circuits
Primary controller