Pump Overrun Time; Minimum Limitation Of The Boiler Return Temperature - Siemens RVA47.320 User Manual

Benefit
Description
Setting
Effect
Example
Note
Benefit
Description
Siemens Building Technologies
HVAC Products
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
0...20
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.
HK
Q
ON
OFF
Y
TVNw
TVRw
HK Operating mode
Q Pumps
Y External mixing valve (via LPB)
TVNw Nominal flow temperature setpoint
TVRw Reduced flow temperature setpoint
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.
Basic Documentation RVA47.320
Description of the OEM settings
Unit
min
tPN
Nominal operation
Reduced operation
tPN Pump overrun time
Factory setting
5
t
t
t
113/166
CE1P2379E
15.07.2002