Siemens RVL481 - Frost Protection for the Boiler

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Siemens Heating and D.h.w. Controller RVL481 CE1P2541en
Building Technologies 12 Function block "Boiler" 20.05.2008
1
0
INT
max.
FG
B2
1
0
Y
B2
t
FGI
RSI
2522D09
0
1
0
t
t
t
t
Y
B1
max.
T
Kw
+ 0,5
*
SD
T
Kw
- 0,5
*
SD
T
Kx
RSI
FG
B2
Release of burner stage 2
FGI Release integral
INT Integral
RSI Reset integral
SD Switching differential
t Time
TKw Boiler temperature setpoint
TKx Actual value of boiler temperature
Y
B1
Control signal for burner stage 1
Y
B2
Control signal for burner stage 2
12.4.3 Frost protection for the boiler
Frost protection for the boiler operates with fixed values:
• Switch-on point: 5 °C boiler temperature
• Switch-off point: Minimum limit of the boiler temperature plus switching differential
If the boiler temperature falls below 5 °C, the burner will always be switched on until the
boiler temperature has crossed the minimum limit by the amount of the switching differ-
ential.