Boiler Protection - Viessmann KW10 Installation, Start-Up And Service Instructions Manual

Additional Information

Boiler Protection

24
Boiler Protection
Minimum boiler temperature protection has been selected for all Vitotronic
controls. It is the responsibility of the installer to determine the requirements of
the boiler for each specific installation. The minimum boiler temperature function
may be disabled; to do so, refer to table in subsection "Minimum Boiler
Temperature Setting".
The boiler construction determines the necessity of a minimum boiler temperature
protection function.
Minimum boiler protection is the result of two separate functions of the
Vitotronic, KW10 control:
– activation of the burner
– deactivation of the space heating pump.
The Vitotronic 100, KW10 control uses a pump aquastat (PA) in conjunction with
an Outdoor Reset Control (ORC) to maintain a minimum boiler temperature. The
aquastat uses a probe-type mechanical limit which monitors the boiler water
temperature. When the boiler water temperature drops below the setpoint of the
pump aquastat, the burner activates and the space heating pump is deactivated.
The ORC also controls the burner by sensing the boiler temperature through the
electronic boiler sensor. When the boiler water temperature drops below the
selected setpoint temperature, the ORC will activate the burner and deactivate the
space heating pump. This only occurs when the room thermostat initiates a call for
heat. The room thermostat may be jumpered to provide a constant call for heat.
The ORC will also deactivate the space heating pump when connected to the
DHW pump module.
The space heating pump may be connected to the Vitotronic 100, KW10 control
in one of two ways:
– using a boiler-mounted pump junction box
– using a DHW pump module (accessory).
The presence of the boiler-mounted pump junction box is determined by the
boiler-specific construction.
When the space heating pump is connected to the boiler-mounted pump junction
box, the pump is deactivated when the boiler water temperature drops below the
pump aquastat setpoint. If continuous operation of the space heating pump is
required, a separate power supply connection is needed. When connecting the
pump to a direct power supply, the use of a pump on/off switch is recommended.
When the space heating pump is connected to the boiler via the DHW pump
module, pump operation is similar to that with pump connection via the pump
junction box. When the boiler temperature drops below the aquastat setpoint, the
space heating pump is switched off. If a DHW pump is connected, it also is
switched off. To modify pump operation, refer to table in subsection "Minimum
Boiler Temperature Setting".
Burner activation is similar to that of the pump control. When the boiler
temperature drops below the pump aquastat setpoint, the burner is activated. The
pump aquastat controls the burner operation when the boiler temperature is below
the aquastat setpoint. If the ORC detects that the boiler water temperature has
dropped below the setpoint, the burner will be activated by the ORC control.