John Wood atmospheric gas water heater pilot will not stay lit; pilot lights briefly then goes out when knob is released

Safety: Turn the gas control knob to OFF and wait at least 5 minutes before relighting to clear any gas.

• 1. Observe pilot flame: When lighting, ensure the pilot flame fully engulfs the top 10–12 mm of the thermocouple. A small or yellow flame may not heat it enough.
• 2. Clean pilot orifice: Turn gas off. Remove the pilot tube from the burner assembly and gently clean the orifice with compressed air. Do not enlarge the opening.
• 3. Tighten thermocouple connection: At the gas control valve, snug the thermocouple nut by hand plus a small additional turn with a wrench. Do not overtighten.
• 4. Replace thermocouple: If the pilot still will not stay lit, install a new John Wood-compatible thermocouple of the same length and type.
• 5. Relight and test: Follow the lighting instructions on the heater label. Hold the pilot button down for 30–60 seconds before releasing. If it stays lit, switch to ON and verify burner operation.