F4 error, burner does not ignite, you may hear clicking but no flame

Safety first: Switch off power and close the gas isolation valve. Ventilate the area if you suspect gas smell. Do not use open flames.

• Verify gas supply: Ensure the gas cock to the Protherm heater is open. Check that other gas appliances in the home are working to confirm supply.
• Bleed air from gas line: After a long shutdown or new installation, air may be in the gas line. A qualified technician should perform safe purging and ignition attempts.
• Inspect ignition electrode: Remove the burner cover and check the ignition electrode for cracks, heavy deposits, or misalignment. Clean and adjust the gap according to Protherm specifications.
• Check ignition cable and connections: Ensure the cable from the PCB to the electrode is intact and firmly connected. Look for signs of arcing to chassis.
• Test gas valve: With a manometer and under technician supervision, verify that the gas valve receives power during ignition and that outlet pressure is correct. Replace the gas valve if it does not open or is stuck.
• PCB check: If ignition spark is absent and the electrode and cable are good, the ignition transformer on the main PCB may be defective and the board should be replaced.

Warning: Gas valve and combustion work must be done only by licensed gas service personnel.