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Siemens Building Technologies
Basic Documentation RVP540 / RVP550
CE1P2488en
HVAC Products
Description of the EXP settings
18.10.2002
5.9 Operating mode of the boiler
•
The boiler temperature is maintained only if required
The setting defines whether it is necessary or desirable to maintain a minimum boiler
return temperature.
Setting range
Unit
Factory setting
0...2 –
1
The following settings are available:
0
Continuous operation (without extended burner running time)
The boiler operates at the minimum boiler temperature level (operating line 270),
independent of whether or not the consumers call for heat. Exception Standby
1
Automatic operation (without extended burner running time)
The boiler is operated only when one of the consumers calls for heat. If the de-
mand for heat drops below TKmin, the boiler is still maintained at the minimum
boiler temperature level (operating line 270).
2
Automatic operation (with extended burner running time)
The boiler is operated only when one of the consumers calls for heat. The effec-
tive boiler temperature setpoint is used, even if it lies below TKmin (operating
line 270).
If the boiler temperature drops below the setpoint by half the boiler's switching
differential (SDK/2), the burner will be put into operation until the boiler tem-
perature has exceeded TKmin by one switching differential (extended burner
running time).
Of course, if the demand for heat by one of the consumers exceeds the minimum boiler
temperature, the required setpoint will be maintained.
In the standby mode , minimum limitation is deactivated. The boiler temperature is
maintained at required level only when there is demand for heat. The protective func-
tions will remain active, however.
Without
extended burner running time
With
extended burner running time
20
10
0
-10
-20 °C
40
30
60
50
°C
TK
TKmin
TKw
SD
K
23
73Z
26
0
20
10
TAgem
70
20
10
0
-10
-20 °C
40
30
60
50
70
TK
TKmin
TKw
SDK
244
0D2
7
0
20
10
TAgem
°C
Benefit
Description
Setting
Effect
Note
Standby
Extended burner
running time
