Adjustment And Safety Devices; Pump Capacity/ Head - Potterton Sirius two WH Instruction Manual

16. ADJUSTMENT AND SAFETY DEVICES

The boiler has been designed in full compliance with European reference standards and in particular is equipped with the fol-
lowing:
• Limit thermostat
Thanks to a sensor placed on the CH flow line, this thermostat interrupts the flow of gas to the burner if the water in the primary
circuit overheats. Under such conditions the boiler is blocked and only after the fault has been eliminated can it be ignited again
by pressing .
It is forbidden to disable this safety device.
• NTC flue sensor
This device is positioned on the fumes duct. The electronic board stops gas from flowing to the burner in case of over heating.
Press to re-establish normal operating conditions.
The above reset operation is only possible if the temperature is less than 90°C.
It is forbidden to disable this safety device
• Flame ionisation detector
The flame sensing electrode guarantees safety of operation in case of gas failure or incomplete ignition of the main burner. In
these conditions, the boiler blocks. Press
• Hydraulic pressure switch
This device allows the main burner to be ignited only if system pressure is higher than 1 bar.
• Pump post-circulation
The electronically-controlled pump post-circulation function lasts 3 minutes and is enabled, in the heating mode, if the ambient
thermostat causes the main burner to go out.
• Antifreeze device
The electronic boiler management system includes an "antifreeze" function for the heating and DHW systems which, when flow
temperature falls below 5°C, operates the burner until a flow temperature of 30°C is reached. This function is enabled when the
boiler is switched on, the gas supply is open and the system is correctly pressurised.
• Pump anti-block function
If no heat demand is received in the heating and/or DHW modes for 24 consecutive hours, the pumps will automatically start and
operate for 10 seconds.
• Hydraulic safety valve (heating circuit)
This device is set to 4 bar and is used for the heating circuit. Connect the safety valve to a drain trap. Do not use it to drain the
heating circuit.
• Heating pump pre-circulation
In case of a heat demand in the heating mode, the appliance can pre-circulate the pump before the burner is ignited. This pre-
circulation phase last from a few seconds to a few minutes, depending on the operating temperature and installation conditions.
• Gas pressure switch
This device enables the main burner only to be switched on if the gas pressure is over 12 mbar.
The functions performed by the adjustment and safety devices are only operative if the boiler is switched on.

17. PUMP CAPACITY/ HEAD

The hydraulic pump, supplied as an accessory kit from POTTERTON COMMERCIAL, is a modulating pump. The purpose of the
pump is to circulate the water between the boiler and the hydraulic separator.
KEY TO PUMP CHARTS - SECTION E
Q RATE OF FLOW
H HEAD
THE PUMP FLOW / HEAD CHARTS CAN BE CONSULTED IN ANNEX "SECTION" E AT THE END OF THE MANUAL.
to re-establish normal operating conditions.
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