Glow-worm Printed Circuit Board 800877

The printed circuit board (PCB) is the control centre of the appliance. It monitors and regulates every process in the boiler through the thermostats, sensors and switches, and it enforces the safety parameters that shut the appliance down when conditions fall outside normal limits. This board is supplied by Glow-worm for the Swiftflow range and carries part number 800877.

• The boiler fails to fire or will not run through a full sequence, with no response from the controls.
• The display or indicator LEDs are dead, intermittent or showing irregular output.
• The boiler locks out repeatedly and will not reset reliably.
• Sensors, thermostats or switches appear to have no effect on boiler operation.
• The board shows visible heat damage, corrosion or tracking around components and terminals.

• Check the GC number on the appliance data badge against the compatibility list to confirm the correct board for your Swiftflow model and control variant.
• Confirm the existing board's part number and compare it with the alternative numbers listed below, as earlier board versions were used across this range.
• Note whether the control variant is Honeywell or SIT, as both are covered by this part number but the appliance identification should still be verified.
• Work on the appliance should be carried out by a competent person, with the electrical supply isolated before the board is removed.