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Benefit
Description
Setting
Effect
On time ratio
Running time
Limitations
Important
Siemens Building Technologies
HVAC Products
5.54 Overtemperature protection for the pump
heating circuit
• Prevents overtemperature in the pump heating circuit
• Enhances the control performance of a pump heating circuit
The flow temperature can be higher than that called for by the pump heating circuit
(e.g. in the case of a higher setpoint demand by another consumer). The controller
offsets the surplus energy by letting the pump cycle, thus preventing the pump heating
circuit from overheating.
Setting range
0 / 1
The pump of the pump heating circuit will cycle in a way that the effect of too high flow
temperatures will be offset.
0
Overtemperature protection deactivated
1
Overtemperature protection activated
The cycling period is fixed at 10 min. This period of time will be broken down according
to the following on time ratio:
−
TVwGef
TRw
ε
=
−
TVxGed
TRw
ε
On time ratio
TVwGef
Demanded flow temperature setpoint
TRw
Current room temperature setpoint
TVxGed
Actual value of the attenuated flow temperature
Multiplication of the on time ratio by the cycling period (10 minutes) gives the number of
minutes for which the pump runs.
This means that with an on time ratio
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 will be activated and deactivated at the following switching points:
• Pump continuously ON
• Pump continuously OFF
Function "Room temperature switching differential" (operating line 722) of a room sen-
sor – if present – overrides that of "Overtemperature protection for the pump heating
circuit".
Basic Documentation RVP540 / RVP550
Description of the EXP settings
Unit
–
ε
of 0.6, the pump runs for 6 minutes and is then
ε
TVxGed
≤
TVwGef (
TVwGef
≤
TRw
<
TVxGed
Factory setting
1
≥
1)
CE1P2488en
18.10.2002
313/348
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