Error 87

Safety first: If you smell gas, evacuate the property immediately and call the gas emergency number. Do not attempt any repairs. Always isolate mains electricity to the boiler before doing physical checks on the appliance. If you are not trained or unsure, stop and call a Gas Safe registered engineer.

Initial homeowner checks you can safely try:

1) Reset the boiler once: press and hold the reset button as per the manual (typically 5–10 seconds). If it restarts and runs normally, monitor for recurrence. Do not keep resetting repeatedly if the code returns.

2) Check mains power supply to the boiler and any external switches or fused spur — ensure the boiler has power.

3) Check system water pressure on the boiler gauge — aim for approximately 1–1.5 bar (within manufacturer 1–3 bar). Top up using the filling loop only if pressure is low and you know how to do so safely.

4) Inspect the external flue terminal for obvious blockages (birds’ nests, leaves, snow, ice). Clear any visible external obstruction without entering the boiler internals.

5) In cold weather check the condensate pipe for freezing (common cause of related codes). If frozen, thaw with warm (not boiling) water or a warm cloth; then restart the boiler.

6) Ensure air vents or room ventilation around the boiler are not blocked and the installation room is adequately ventilated.

If the fault persists or for deeper diagnostics (these steps should be carried out by a qualified engineer):

1) Engineer to check fault memory and live data on the PCB to confirm error 87 and any associated errors.

2) Verify fan operation: observe fan running command, measure supply voltage to the fan motor and check motor spin and impeller for obstruction or damage.

3) Inspect and test the air pressure switch and associated tubing: ensure the differential pressure hose is intact, free of blockages, correctly routed and not split or disconnected.

4) Check the flue and condensate route for internal blockage, restriction or leakage affecting pressure sensing.

5) Inspect wiring and connectors between fan, pressure switch and PCB for loose connections, corrosion or burned joints.

6) If electrical supply to the fan and pressure switch is correct but the fan fails or the pressure switch gives inconsistent readings, replace the faulty component (fan assembly or pressure switch). If wiring and components test OK but errors persist, investigate the PCB and replace if deemed faulty.

7) After any repairs, test the boiler through a full start/stop cycle and monitor for correct operation and absence of fault codes. Confirm plume, flue gas path and safety interlocks operate correctly.

Final note: Because fan and air-pressure faults affect safe flue operation and combustion, if the simple homeowner checks above do not clear the fault you should contact a Gas Safe registered engineer. Do not attempt internal electrical or gas-related repairs yourself. Repeated lockouts or intermittent faults require professional diagnosis and repair.