Pilot light won't stay lit when you turn knob from pilot to on, it goes out as soon as the knob pops up before you can turn it to on

by Tina
(San Diego, CA)

pilot light on my Reliance 501 gas water heater won't stay lit when you turn it from light pilot to on, it goes out as soon as the knob pops up. What do I do? I have no hot water, and cold, freezing cold showers really ain't my thing!! Can you help me Please?I would like to try to fix it myself! How can I do a test to see what's wrong with it? How can I troubleshoot it so i know what needs fixing??

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Apr 14, 2016
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starstarstarstarstar 		Clean your flame sensor.
by: John

If I'm correct in assuming you held down the knob for a good 90 seconds after the pilot lit and the pilot still went out when you released it, I'd say the flame sensor is corroded. Just how handy are you? First, you'll need to shut off the gas at the inlet pipe by rotating the valve 90 degrees so that its direction is perpendicular to the direction of the pipe instead of in line with it. This valve can be a little snug. Some have levers on them, some don't. If your's has a lever but you can't budge it by hand, try grabbing it with something that'll provide you some extra leverage but be careful you don't push so hard that you snap it off. If your's doesn't have a lever, a Crescent wrench should turn the hub on the valve nicely. If it still won't turn, try some penetrating oil on it to help loosen it.

Once that's accomplished, you'll need to start disconnecting things connected to the gas control valve so you can remove the burner. This goes pretty quick. Just pay attention so you can put it all back together when you're done. There'll be an access plate at the base that just lifts out. Under that, there'll be another plate held in place with a few bolts or screws. Once you remove them, you'll be able to slide the whole burner assembly out. You'll see how the larger pipe goes to the main burner and how the smaller pipe goes to the pilot. You can blow through both to make sure they're not obstructed but it's highly unlikely they are.

The flame sensor sits right beside and in the flame of the pilot. It will probably look like a small metal tube and will likely be caked in grimy ash. The cake is preventing it from seeing the pilot's flame and telling the control valve that it's okay to send gas. It's what keeps gas from filling the room if the pilot ever goes out. Get some steel wool or emery cloth and rub it nice and clean. Do a good job or you'll just have to come back and do it again. Then check to see if the sensor appears to be positioned so it's in the flame of the pilot. It likely is but in case it's not, bend it gently so that it is. Now put it all back together the same way you took it apart. Turn the gas back on and try to reignite the pilot again as before. If you still have the same problem, the gas control valve on the water heater will most likely need to be replaced.

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