Pilot on Vaillant gas water heater keeps going out.

If the pilot light usually keeps running but only goes out from time to time – I would suggest you look at the pilot light – you will probably find that it is partically blocked or dirty and when the main burner shuts off it is “sucking” out the pilot flame.

---

Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians

Could be possibly the thermocouple.

» This message has been edited by AKPlumber on 29 December 2004

Would have thought that if it was the thermocouple the pilot flame itself would not hold at all – it seems this one holds and goes out from time to time – not all the time.
You could the thermcouple lead and make sure it reads more than 25 millivolts when heated which would then show it to be ok. I would suspect the pilot burner most of all in this instance from the description given.

---

Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians

Peter is most likely correct about the pilot tube being obstructed, but there are two other possibilities. The regulator assembly could be faulty, such that when it switches thermostatically from “heating” to “pilot” or vice versa it shuts the pilot off. This also sometimes happens with a faulty pilot thermocouple. Also, there could be a downdraft from the flue that blows out the pilot after a heating cycle.

The first thing to do, as Peter says, is to have the pilot orifice cleaned. If that doesn’t work, replace the entire regulator, thermocouple, and pilot. The set of parts will run about $125 around here. At this point, you might just consider buying a new water heater, especially if the water heater is more than 8 years old.

If you STILL have the problem, check your flue, especially the damper and the draft diverter (that little hood atop the heater that leads into the flue pipe—every heater needs one).

NtP