Siemens RVA53.242 - 5.8 Operating mode of boiler

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Siemens Building Technologies Basic Documentation RVA63.242, RVA53.242 CE1P2373E
Landis & Staefa Division Description of OEM settings 26.03.2001
5.8 Operating mode of boiler
A minimum 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 – 2
The following settings are available:
0 Continuous operation:
The boiler operates at the minimum boiler temperature level (operating line 81),
independent of whether or not the consumers currently call for heat. Exception
Stand-by
Without extended burner running time.
1 Automatic operation:
The boiler is operated only when one of the consumers calls for heat. If the
demand for heat drops below TKmin, the boiler is still maintained at the minimum
boiler temperature level (operating line 81).
Without extended burner running time.
2 Automatic operation:
The boiler is operated only when one of the consumers calls for heat. The
effective boiler temperature setpoint is used, even if it lies below TKmin
(operating line 81).
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
temperature has exceeded TKmin by one switching differential (extended burner
running time).
With 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 stand-by mode of all heating circuits, minimum limitation is deactivated. In that
case, the controller must be in "standalone“ mode (device address 0). The boiler
temperature is maintained at required level only when there is demand for heat. The
protective functions will remain active, however.
5.8.1 Extended burner running time
Without extended burner running time With extended burner running time
20 10 0 -10 -20 °C
40
30
60
50
°C
TK
TKmin
TKw
SDK
2373Z26
0
20
10
TAgem
70
20 10 0 -10 -20 °C
40
30
60
50
70
TK
TKmin
TKw
SDK
2440D27
0
20
10
TAgem
°C
Benefit
Description
Setting
Effect
Note
Standby