Basic Documentation

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Siemens Modular Heating Controller RMH760B CE1P3133en
Building Technologies 10 DHW heating 2017-09-29
From the consumer’s point of view, a load increase can be effected in the form of pump
and / or mixing valve overrun. This will force the consumer to continue to draw heat.
Overrun is not possible with direct DHW heating since there is no pump on the
secondary side. Overrun does not act on the circulating pump.
By setting the DHW priority, a load reduction on the heating circuits can be enforced.
When the priority is active, there is thus more heat available for DHW heating, and the
charging time becomes shorter.
For more detailed information, refer to section 10.10 " DHW priority".
10.8 Limitation and protective functions
10.8.1 DHW discharging protection
The flow temperature is monitored to prevent the storage tank from being discharged.
Discharging protection can become active during storage tank charging or during
overrun and deactivate the charging pump or primary pump.
To ensure that the function will also be performed when the charging pump is
deactivated (with no flow past the sensor), the flow temperature of the primary
controller or that of the boiler is used.
If a primary controller is used without a pump, it is possible that there will be no flow
past the flow temperature sensor. For this reason, discharging protection can be
deactivated.
In the case of plants with heat exchanger, the primary flow temperature is used, if
available.
The flow temperature must be acquired either locally by the same controller or by some
other device which communicates via bus.
For detailed information, refer to chapter 15 "Communication".
Main menu > Commissioning > Settings > … or
Main menu > Settings > DHW > DHW
Operating line
Range
Factory setting
Discharge protection
Yes / No
Yes
During storage tank charging, discharging protection switches the respective charging
pump off if:
DHW plant type Condition for switching off
Discharging
protection with
DHW 1
DHW 2
Flow temperature < [storage tank
temperature* + 1/8 setpoint
increase of DHW charging]
Primary pump
DHW 3
DHW 4
DHW 5
Primary flow temperature <
[storage tank temperature** + 1/
8
setpoint increase of heat
exchanger]
Secondary pump
During overrun, discharging protection switches the primary pump off if:
DHW plant type
Condition for switching off
DHW 1
DHW 2
DHW 4
DHW 5
Flow temperature < storage tank temperature**
Load increase
Flow temperature
⇒
Settings
Storage tank charging
active
Overrun active