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Siemens Building Technologies
Basic Documentation RVA47.320
CE1P2379E
HVAC Products
Description of the OEM settings
15.07.2002
5.3
Pump overrun time
•
Protects the boiler against overtemperatures
•
Use of residual heat in the boiler.
Overrun of the primary, heating circuit and d.h.w. charging pump ensures that residual
heat will be carried away from the pressureless header. This makes certain that the
boiler pump controlled by the BMU will be able to draw the residual heat from the boiler,
thus avoiding boiler overtemperatures and preventing the manual reset safety limit
thermostat from cutting out.
1.
Press the line selection buttons to select line 8OEM.
2.
Press the + / - buttons to set the pump overrun time.
Setting range
Unit
Factory setting
0...20 min 5
All pumps that, at the time of burner shutdown of the last boiler, were operating,
continue to run for the period of time set here. At the same time, the previous flow
temperature setpoint remains valid, allowing the mixing valves of the controllers
connected to LPB to stay open.
ON
OFF
t
HK
Q
t
TVNw
TVRw
2373
Z2
8
Y
t
tPN
HK Operating
mode
Q Pumps
Y
External mixing valve (via LPB)
TVNw Nominal flow temperature setpoint
TVRw Reduced flow temperature setpoint
Nominal
operation
Reduced
operation
tPN
Pump overrun time
With no burner shutdown, the general pump overrun time is one minute.
5.4
Minimum limitation of the boiler return
temperature
•
The minimum boiler return temperature can be adjusted
•
The effect on the consumers can be adjusted
The setting defines the permitted minimum boiler return temperature.
Benefit
Description
Setting
Effect
Example
Note
Benefit
Description