Remedy
Tip: Check the ceramic insulator is not damaged, this can cause the spark to earth, twist and pull the ceramic insulator to ensure it is not broken.
▶ Check the gas supply to property and the inlet on the gas valve (→ Chapter 10.11, page 70).
▶ Check the low pressure when the gas valve opens.
▶ Gas valve failing to open: check for voltage to the valve and for possible blockage on inlet filter of the gas valve.
▶ Obstruction in the air intake to the fan leading to incorrect CO2 ratio. Back flow prevention valve is damaged or stuck (→ Chapter 10.8, page 67).
▶ Condensate trap is blocked or restricted. Condensate pipe is frozen (→ Chapter 9.9, page 58).
▶ Flue is blocked or restricted.
▶ Heat exchanger is blocked or restricted (→ Chapter 10.13, page 71).
▶ Check the burner for damage.
▶ Check the ignition electrode or the lead failure (→ Chapter 9.10, page 59).
▶ Check the flame sense or the lead failure.
▶ Check the rectification ground (black wire to heat exchanger).