GSW gas water heater burner does not light even though the pilot is on (standing pilot models)

Safety: Turn the gas control knob to OFF and allow the heater to cool. Do not attempt to disassemble the gas valve.

• Verify pilot flame: Ensure the pilot is strong and properly heating the thermocouple. If the pilot is weak, address that first.
• Temperature setting: Confirm the thermostat dial is set above the current water temperature. Turn it up slightly and listen for a click indicating the thermostat is calling for heat.
• Inspect burner orifice: With gas off, remove the burner assembly and clean the main burner orifice with compressed air. Do not enlarge the orifice.
• Check sensing bulb (if equipped): Some older GSW valves use a capillary bulb in the tank. If kinked or broken, the valve must be replaced.
• Replace gas control valve: If the pilot is stable, burner orifice is clear, and the burner still will not light, the gas control valve is likely defective and should be replaced by a licensed gas technician.