Water heater pilot light keeps blowing out from drafts

Symptoms

• Pilot goes out specifically during windy weather or when doors/windows are open nearby
• Relighting works fine but it blows out again later
• Water heater is in a garage, closet, or exterior wall location
• No thermocouple issue found on inspection

Likely causes

• CommonInsufficient combustion air supply to the water heater closetA sealed or poorly vented closet can create drafts as air is pulled in to feed combustion.
• CommonBackdrafting from the vent flue due to wind or a blocked chimney/ventWind gusts hitting the vent termination can occasionally push air back down the flue.
• PossibleNearby exhaust fans (bathroom, kitchen, dryer) depressurizing the spaceRunning exhaust fans can pull air, and sometimes flue gases, back down through the water heater vent.
• PossibleDamaged or improperly installed vent pipeGaps or disconnected sections in the vent can let outside drafts reach the pilot area.

What to do

1. Note the conditions when the pilot blows out, such as windy days or when a specific fan or door is used.
2. Check that the water heater closet has proper combustion air vents (louvers near the floor and ceiling) that aren't blocked by stored items.
3. Inspect the visible vent pipe from the water heater to where it exits the house for gaps, disconnections, or damage.
4. Avoid running strong exhaust fans in tight proximity to the water heater closet if this seems to trigger the issue.
5. Check outside at the vent termination for damage, blockage, or a cap that's come loose in the wind.
6. If the pilot blows out consistently under normal conditions with no obvious draft, have the venting professionally assessed.

Tools and parts

• Flashlight

When to call a pro

If the vent, combustion air supply, or backdrafting seems to be the issue, have a licensed plumber or HVAC technician inspect and correct the venting.

Safety