Siemens LMS14 User Manual

161/617
Building Technologies Division User Manual LMS14... CC1U7471en
6 The settings in detail 07.05.2014
6.5.23 Overtemperature protection for the pump heating circuit
Line no. Operating line
HC1 HC2 HC3
820 1120 1420 Overtemp prot pump circuit
Off
On
In the case of heating plant with pump heating circuits, the flow temperature of the
heating circuit can be higher than the flow temperature called for by the heating curve,
due to requests from other heat consumers (mixing heating circuit, DHW charging,
external heat demand), or due to a parameterized minimum boiler temperature. As a
result of too high flow temperatures, the pump heating circuit would assume excessive
temperatures. Function Overtemperature protection for pump heating circuits ensures
that the amount of heat supplied to pump heating circuits corresponds to the demand
from the heating curve by activating/deactivating the pump.
The cycling period is fixed at 10 min. This period of time is broken down according to
the following on time ratio:
Required flow temperature setpoint – room temperature setpoint
On time ratio = -----------------------------------------------------------------------------------------------
Attenuated actual value of flow temperature – room temperature
setpoint

Multiplying the on time ratio by the cycling period (10 minutes) gives the number of
minutes during which the pump is running. This means that if the on time ratio is 0.6,
the pump runs for 6 minutes and is then switched off for the remaining 4 minutes of the
cycling period.
The pump’s running time is set to a minimum of 3 minutes. The pump’s off time is set to
a minimum of 2 minutes. Also, the pump is activated and deactivated at the following
switching points:
 Pump continuously On Attenuated actual value of flow temperature  required
flow temperature setpoint (on time ratio 1)
 Pump continuously Off Required flow temperature setpoint  room temperature
setpoint  attenuated actual value of flow temperature
Note!
The overtemperature protection function can switch off the consumer pump.
Therefore, if overtemperature protection is active, you must ensure that the boiler
flow rate is correct, because there may not be any other consumer pumps still
running except this one.
Overtemp prot pump
circuit
On time ratio
Running time
Limitations

Siemens LMS14 Specifications

General

Brand	Siemens
Model	LMS14
Category	Control Unit
Language	English