Baxi 5137531 Potterton & Main Honeywell Air Pressure Switch

The Baxi 5137531 is a fan pressure switch made by Baxi for its domestic gas heating appliances. It sits in the air path around the combustion fan and responds to the pressure difference the fan creates, opening or closing its contacts to tell the control board that airflow has been established. The board uses that signal to allow the ignition sequence to continue, and to shut the appliance down safely if the fan stalls, the flue becomes restricted or the pressure reading falls outside the expected range. Because it is pressure-operated rather than mechanically linked, it reacts to changes in flow across the whole operating range of the fan.

• The boiler locks out or fails to fire once the fan has started
• Ignition is attempted repeatedly without a flame being established
• The fan runs continuously, or cycles on and off, without the boiler firing
• Lockouts are intermittent and clear on reset before returning
• A fan or air pressure fault code appears on the appliance display

• Read the data badge on the appliance and note the model and GC number
• Compare the part number on the existing switch with BAXI5137531
• Check whether the sensing tube and gasket can be reused, as these are often transferred from the old switch