Adjustment And Safety Devices; Pump Capacity/ Head - Baxi NUVOLA DUO-TEC GA Series Instruction Manual For Users And Fitters

16. ADJUSTMENT AND SAFETY DEVICES

The boiler has been designed in full compliance with European reference standards and in particular is equipped with the follow-
ing:
• 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.
It is forbidden to disable this safety device
• NTC fumes sensor
This device is positioned on the fumes-water exchanger. The electronic board stops gas from flowing to the burner in case of over
heating.
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.
• Hydraulic pressure switch
This device allows the main burner to be ignited only if system pressure is higher than 0.5 bars.
• 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.
• Anti-block pump function
If no heat demand is received in the heating and/or DHW modes for 24 consecutive hours, the pump will automatically start and
operate for 10 seconds.
• Three-way valve anti-blockage function
If no heat demand is received for a period of 24 hours, the three-way valve performs a complete switching cycle.
• Hydraulic safety valve (heating circuit)
This device is set to 3 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.

17. PUMP CAPACITY/ HEAD

This is a high static head pump fit for installation on any type of single or double-pipe heating systems. The automatic air valve
incorporated in the pump allows quick venting of the heating system.
KEY TO PUMP CHARTS - "SECTION" E
Q WATER FLOW RATE
H HEAD
MIN Minimum speed of modulation
MAX Maximum speed of modulation
37 7114043.01 (1-06/13)