2

My in-garage 50 gallon gas-fueled water heater stops working once a month or so when there’s a big wind storm. Once I observe the hot water isn’t working I need to turn it off for ten minutes then relight it. Sometimes I smell gas in the garage and take care to ventilate it (although this often happens in freezing weather).

It vents through the wall and into my masonry chimney which I’d estimate is 35’ tall (the garage makes up the full ground floor and there are two habitable stories above).

Is this something that can be remedied in the garage, or will I need some sort of modification to the chimney cap? If so what trade do I call for that? Any other advice?

6
  • 4
    Get a gas-certified engineer out. If the pilot can go out & the gas not auto-shut off, you have a potentially explosive problem.
    – Tetsujin
    Commented Jan 16, 2023 at 16:01
  • Consider draft-proofing the garage.
    – gnicko
    Commented Jan 16, 2023 at 16:43
  • 1
    @gnicko - there should be no direct air-air path between garage & pilot light. The unit should only be open to the outside.
    – Tetsujin
    Commented Jan 16, 2023 at 16:46
  • 2
    @Tetsujin Many gas appliances that have a pilot light burn air from the surrounding room. Exhaust is often by a natural draft convection. An appliance like this is open to the room and could easily malfunction due to wind.
    – Greg Hill
    Commented Jan 16, 2023 at 18:58
  • @GregHill - I've never seen one, but there may be different rules in different territories. [They're not absolutely gas-tight, but they are not 'open to the air' indoors, like a living room gas fire.]
    – Tetsujin
    Commented Jan 16, 2023 at 19:01

1 Answer 1

7

As wind blows against a building some areas experience a rise in air pressure and other areas experience a drop in air pressure. That difference in pressure can cause a surprising draft through the flue. If the air current is strong enough it'll snuff out the pilot. When the pilot goes out the thermocouple will cool down causing the gas valve to shut off the flow of gas to the pilot.

If you're smelling gas then it could be that you've discovered the outage very quickly after the pilot extinguished, or it could be that the valve is not closing as quickly as it should. You could do some experiments to better determine what's going on.

Honestly, the best thing you could do to eliminate this problem is to replace the water heater. A model with hot surface or spark ignition has no pilot and will always light itself automatically. A model with sealed combustion has two pipes going outdoors (one for air intake and the other for exhaust); if those pipes are exposed to the same face of the building then wind will never cause a significant pressure differential between them (in practice, though, a sealed combustion appliance also won't have a pilot anyway).

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.