Water Heater Question...

[DriftInn]

When trying to light my water heater in my '74 '31, the pilot lights normally, but the main burner never comes on, no matter how long the pilot runs. Is this a common problem? Bag temp sensor? Regulator? Anyone with any experience? Much appreciated.

[RichardT]

I am not sure of the answer but this post will get you back on the beginning of the list. Cant anyone help?
I have always been able to get them to work with a little fiddling around, but would be afraid to suggest anything as they can be dangerous.
Just make sure you keep your face away and to the side whenever lighting a water heater as the can go POOF! and you could lose your eyebrows or worse, also always know where your fire extiguisher is and shake it once in a while so it is ready to use when you need it.

[davidz71]

DriftInn,
You said that you are able to light the pilot light and it stays lit. OK, are you then turning the thermostat to ON and you don't get a thing?

[DriftInn]

David,
Yes, exactly. I light the pilot, holding the button down, and it burns normally. But, as soon as I turn the knob to ON, the pilot goes out. Or, if I let up on the pilot button, it goes out as well. I've tried lighting the main burner by turning the switch to ON, then trying to light it manually. No go.
Any idea if there is a way to test the temp sensor? I assume that if it did not register the heat from the pilot, it would prevent the main burner from starting, right?
Any help greatly appreciated....

Oh, one more piece of info, when I bought trailer, I was able to get the water heater to work, but barely. It always wanted to go out, or not burn very clean and evenly. What about cleaning the
"regulator", or what ever you call the device with the switch , main burner, etc... on it.

[Mike76251]

I just had the same problem and found the thermistor (ECO) had shot.
If I were you I would test or replace the thermocouple first.
To do this you need to pull the thermoc. and check the voltage with a digital multimeter while heating the end.
It should put out .400 or so milliamps.
It might be easier for you just to replace the thermocouple as it is not expensive.

If it still doesn't work after this then I would suspect the ECO.
This is a $3.00 part but on some heaters you have to replace the gas valve to fix it......$90 for it unless you are handy with a mig or tig welding machine.

As this heater did not work right when it was working you might look at a trip to a shop to have it checked out.
That or a new heater mind you.

[davidz71]

Since the pilot light will not stay on when you let off the button, my service manual says the following could be wrong:
Too much primary air
Defective magnetic valve
Need new thermocouple lead
Thermocouple lead connection loose
Pilot line clogged
Improper pressure on regulator
Pilot not striking thermocouple properly
Wrong pilot burner
Heater subjected to strong cold drafts
E.C.O. switch contacts open

Checking the E.C.O. involves hooking up an adaptor and using a milivolt meter. If you start the unit up and the closed circuit output test shows less than 8 milivolts then replace the thermocouple. If in excess of 8 milivolts, blow out the pilot. A good magnet assembly should remain locked for a drop of 5 milivolts or more from original stabilized output. If magnet does not operate properly, replace magnet.

Based on just this section, if you have checked to ensure that your regulator is operating properly and that you have checked all gas lines to be sure they are not restricted then I would try Mike's suggestion next or take it to someone who has the proper equipment to check it out.