Adjustment And Safety Devices - Baxi Nuvola 3 Comfort Operating And Installation Instructions

High performance gas-fired wall-mounted boiler

Table of Contents

22. ADJUSTMENT AND SAFETY DEVICES

This boiler has been designed in full compliance with European reference standards and, in particular, it is fitted with the following:

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Air pressure switch (model 140 Fi - 240 Fi - 280 Fi - 320 Fi)

This device (17 - figure 20) only allows the burner to ignite if the exhaust flue duct is in perfect working order.

In the event of one or more of the following faults:

• flue terminal obstructed

• venturi tubes obstructed

• fan blocked

• venturi tube connection - pressure switch tripped

The boiler remains on standby and error code E03 is displayed (see table in section 9).

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Fumes thermostat (model 240 i - 280 i)

This device (15 - figure 21), the sensor of which is positioned to the left of the fumes hood, interrupts the flow of gas to the main burner if the flue is

obstructed and/or there is no draught.

In these conditions the boiler shuts down and displays error code E03 (section 9).

To restart immediately, after having removed the cause of intervention, see section 9.

It is forbidden to disable this safety device

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Safety thermostat

Thanks to a sensor placed on the heating delivery line, the thermostat interrupts the flow of gas to the burner if the water in the primary circuit

overheats. In these conditions, the boiler is blocked and only after the fault has been eliminated can it be ignited again (See section 9).

It is forbidden to disable this safety device

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Flame ionisation detector

The flame sensing electrode, located on the right-hand side of the burner, guarantees safety of operation in case of gas failure or incomplete ignition

of the burner.

In these conditions, the boiler is blocked after 3 ignition attempts.

To re-establish normal operating conditions, see section 9.

•

Hydraulic pressure switch

This device allows the main burner to be ignited only if system pressure is higher than 0.5 bars.

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Pump overrun for heating circuit

The electronically-controlled pump post-circulation function lasts 3 minutes (F17 – section 21) and is enabled, in the heating mode, if the ambient

thermostat causes the burner to go out.

•

Post-circulation of the DHW circuit pump

The pump post-circulation, which is obtained electronically, has a duration of 30 seconds and is activated at the end of operation of the DHW

pump.

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Frost protection device (heating and DHW systems)

The electronic boiler management system includes a "frost protection" function for the heating system which, when delivery temperature falls below

5°C, operates the burner until a delivery temperature of 30°C is reached.

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Lack of water circulation in the primary circuit (probably pump blocked or presence of air)

If there is insufficient or no water circulating in the primary circuit, the boiler blocks and the error code 25E is shown on the display (section 9).

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Anti-block pump function

If no heat demand is received for 24 consecutive hours, the pump will automatically start and operate for 10 seconds.

This function is operative when the boiler is powered.

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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. This function is operative when the

boiler is powered.

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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 tap. Do not use it to drain the heating circuit.