Siemens AVS75.39 Series User Manual page 96

Boiler / burner control
Switching differential of
the boiler
Minimum burner running
time
96 / 239
Siemens
Building Technologies
Line no. Operating line
2240 Switching differential boiler
2241 Burner running time min
The boiler control is designed as a two-point controller for which a switching
difference can be entered.
If a minimum burner running time is parameterized, the burner's switch-off point will
be raised by half the boiler's switching differential within that minimum on time. If,
within the minimum burner running time, the boiler temperature exceeds the
setpoint by more than the full switching differential, the burner will also be shut
down before the minimum on time has elapsed. On completion of the minimum on
time, the burner's switch-off point will be set to the boiler temperature setpoint plus
half the switching differential. This function only acts on the first burner stage.
T
+SDK
TKw
TKw +SDK/2
TKw
TKw- SDK/2
1
tBRmin
0
tBRmin
1
BR
0
T Temperature
t Time of day
tBRmin Minimum burner running time
BR Burner ( 0= off, 1 = on)
TKw Boiler temp setpoint
TKx Actual boiler temperature
SDK Switching differential of the boiler
User manual RVS43.345
The settings in detail
TK
x
tBRmin tBRmin
t
CE1U2354en_021
2013-09-02