Dead gas water heater

[kaneohe]

I normally turn the control on our gas water heater from
ON to PILOT when we leave on a trip. Heater was working fine when we left on last trip. However, when we got back, after switching back to ON, water heater did not turn on. Pilot is on but main flame does not turn on as it normally does.

What is problem, is it just an accident that it died when it did or does turning from ON to PILOT (perhaps 3 to 4x/yr) create the problem? Water heater is 7 yrs old. Worth fixing or not?

[cantlogin]

Try giving that control a sharp rap with the handle of a screwdriver.

[Walt34]

If you know how to replace the gas valve yourself it's worth fixing. If you have to pay someone to do it the repair will be around half the cost of a new heater so you're probably better off buying a new water heater.

[travelover]

Quote:

Originally Posted by cantlogin Try giving that control a sharp rap with the handle of a screwdriver.

+1. They get crotchety in their old age and when you turned it to a new position it stuck. I'd work it back and forth and rap on it to loosen any corrosion or sticking points. It could also be the thermocouple, if it has one.

[ERD50]

Quote:

Originally Posted by travelover +1. They get crotchety in their old age and when you turned it to a new position it stuck. I'd work it back and forth and rap on it to loosen any corrosion or sticking points. It could also be the thermocouple, if it has one.

I agree with some gentle tapping, but I don't think it would be the thermocouple. As I recall, on the ones I've worked on, if the thermocouple circuit is bad, it totally shuts off the gas and even the pilot goes out. I say that because you need to hold it in 'pilot' position long enough for the thermocouple to get hot, or the pilot goes out.

Maybe there are different designs, but that's what I'm familiar with.

Could also be a fault in the thermostat, and it is not 'calling' for heat.

-ERD50

[calmloki]

Quote:

Originally Posted by ERD50 I agree with some gentle tapping, but I don't think it would be the thermocouple. As I recall, on the ones I've worked on, if the thermocouple circuit is bad, it totally shuts off the gas and even the pilot goes out. I say that because you need to hold it in 'pilot' position long enough for the thermocouple to get hot, or the pilot goes out. Maybe there are different designs, but that's what I'm familiar with. Could also be a fault in the thermostat, and it is not 'calling' for heat. -ERD50

+1 good point on thermocouple

[travelover]

Quote:

Originally Posted by ERD50 I agree with some gentle tapping, but I don't think it would be the thermocouple. As I recall, on the ones I've worked on, if the thermocouple circuit is bad, it totally shuts off the gas and even the pilot goes out. I say that because you need to hold it in 'pilot' position long enough for the thermocouple to get hot, or the pilot goes out. Maybe there are different designs, but that's what I'm familiar with. Could also be a fault in the thermostat, and it is not 'calling' for heat. -ERD50

Maybe I'm out of date. On my old furnace and water heater the thermocouple did not stop flow to the pilot, just the main burner. Newer ones, no doubt, have the thermocouple control both.

[kaneohe]

Thanks all for the replies...........here's an interim result: I banged on the part
with the ON/PILOT/OFF control a number of times in both the PILOT and ON positions. No response though being a basic chicken, it's possible I didn't do it
sharply enough........more like a gentle tapping. I notice upon re-reading your comments too that I only did it in 2 fixed positions , rather than hitting while moving the knob....need to keep that in mind next time.

Anyway, I noticed for the first time in 40 yrs that there is a vacation (low temp setting) position on the temp control knob and turned that up.....voila...instant flame. I guess I didn't think about doing that since, in the past, turning the mode knob from PILOT to ON always did the trick. I normally never touch the temp control knob which is set to slightly lower than normal. Is it possible that the ambient temp was warm enough while we were gone that the water didn't need any heating when I switched from PILOT to ON?

Is it better to use that vacation setting on the temp control knob rather than the mode knob (PILOT/ON/OFF ) that I've always used in the past? One reason I might not want to mess with it now is that it seems to have a fairly large hysteresis ......it turns on at some position but turns off at a much lower position so water temp might change if I mess with it. Don't know if it was always like that or not.

Agree w/ the comments about the thermocouple. My experience is that when the TC is new, you only have to hold the button down a short time after lighting the pilot before you release it. As it ages, you have to hold it down longer (sometimes as much as 5 min) or else the pilot will go out.
I told the PG&E serviceman that and he didn't believe me. He got out some test box and tested the TC and pronounced it good as new. 3 mos. later, it was dead.

Anyways, happy ending for now. Thanks again for the help.

[travelover]

Quote:

Originally Posted by kaneohe .............. Anyway, I noticed for the first time in 40 yrs that there is a vacation (low temp setting) position on the temp control knob ................

Is it really 40 years old? Mine is 20 yo and I feel like it is on borrowed time. Anyway, if that old, maybe thermocouple as I mentioned above.

[calmloki]

Quote:

Originally Posted by travelover Maybe I'm out of date. On my old furnace and water heater the thermocouple did not stop flow to the pilot, just the main burner. Newer ones, no doubt, have the thermocouple control both.

Cwap - you are correct. if pilot is out, thermocouple stops flow to both pilot and main, if pilot is burning thermocouple hasn't shut off gas and is working. In this case pilot is reported as burning.

[kaneohe]

Quote:

Originally Posted by travelover Is it really 40 years old? Mine is 20 yo and I feel like it is on borrowed time. Anyway, if that old, maybe thermocouple as I mentioned above.

No, sorry for the poorly worded misleading statement........I was referring to my experience in this house w/ water heaters of which there have been at least 3. This one is 7 yrs old.