AO Smith GCV 50 100 - Pilot Light Won't Stay Lit


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Old 02-11-14, 07:26 PM
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AO Smith GCV 50 100 - Pilot Light Won't Stay Lit

I have an AO Smith GCV 50 100 (Serial # E05J071181) where the pilot light will not stay lit when trying to re-light. Unit is approximately 9 years old with no prior history of repairs.

Issue arose last night when the water in the shower did not stay hot very long. I checked hot water later in the evening and it was cold. I inspected the heater and found the pilot light to be out. I tried to re-light, but pilot would not stay lit after following AO Smith's instructions (hold down pilot button for 1 minute before turning to "ON"), etc. As I released the button, the flame would instantly die out. Flame is 90% blue with some orange "flickers" mixed in.

From some basic research, it appears either the pilot needs to be cleaned or replaced. Replacement is very straightforward. Two questions:

1) Does it appear I'm headed on the right track?
2) How/what needs to be cleaned? Water heater is in our attic with drain pan that makes looking under the unit difficult. Do I just need to remove the black air intake screen and blow compressed air inside?

I found this thermocouple online which appears to be a direct replacement for this model:

Reliance Water Heater #9003542 Nat Gas Pilot Assembly - Amazon.com

Any confirmation on the above would be greatly appreciated.

Fortunately, our house has two water heaters with the working heater serving a 3rd bathroom. However, my wife wants "her" shower fixed so I need to repair ASAP .

Thanks for any assistance provided.
 
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Old 02-11-14, 07:50 PM
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Hello and welcome....

There is an air screen basically called a corderite disk.. It is located between the bottom of the heaters air intake and the bottom of the burner inside the gas chamber...

This needs to be cleaned most likely...

Here read through these... I know I posted a few good posts on how to clean it... Make an attachment for your vacuum. Piece of pvc pipe 3/4 and an elbow...

Search Results | DoItYourself.com
 
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Old 02-11-14, 08:25 PM
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Thanks. My drain pan may prevent me from getting much of any vacuum attachment inside the air inlet where the black grate is. Can this be accessed/cleaned by removing the thermocouple as well?
 
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Old 02-11-14, 08:31 PM
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It can be accessed but you cant vacuum it from inside... You need to vacuum from the bottom...

I snip the drain pans and fold the lip down... When I am done I fold it back up and silicone where I cut...

Last that heater should be at least 7 yrs old...Sometimes its better to replace if cleaning does not fix it...Sometimes the disk gets imbedded too bad... Its past warranty.. Just a thought..
 
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Old 03-30-14, 08:43 PM
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Pilot light

If pilot light won't stay on and you have confirmed air intake is clean and clear vent pipe it could be the thermal couple a meter in series from end of thermal couple to ground and on millivolt DC setting should read 4-5 MV when you have a lit pilot this is what proves to the gas valve and keeps the pilot on. No Millivolt signal no pilot.
 
 

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