AO Smith FSG 40 232 Water Heater Problem

Always Learning

Always Learning

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Hi all, first time poster here. Great forum you have here! :)

I have a problem with a water heater that I can't figure out. The pilot light goes out from time to time. Sometimes once every few days, sometimes not for 6 months. At first, I changed the thermocouple, but that didn't help. Then I figured that maybe some debris could be blocking the little pilot light orifice, so I took that off to tap it on a hard surface and used compressed air to try blowing any debris backwards through the line (though the orifice is so small I don't know if the compressed air got through).

Can anyone shed some light on this?
 
Are you in a very hot climate ( that could be almost anyplace right now!) and is the water heater in the attic?
 
I had a problem before where the supply line was not large enough for everything it was supplying and when another unit turned on it robbed gas from everything else and the pilot light would go out.
 
name the Brand of heater

you have not given anyone much info to go on...

make model, year made ect.... but

if the unit is a Whirlpool flame lock, then you are in trouble


if it is any other good brand it is most likely the gas valve --thermostat High Limit sensor inside it going bad....

you will have to replace the gas valve...


If it is a Kenomre or Smith or State, made after 2003
their is a good possibility its clogged up with lint underneath the unit and that is trouble too...


or if the unit is more than 10 years old,
its already lived its ife...

stick a fork in it... its done
 
Last edited:
I use a special tapered wire called a "pilot broach" to clean out the pilot orifice. You may want to give that a try.

The new thermocouple may not be any good either. Try this test:
1.Turn down thermostat. Leave gas valve on.
2. Blow out the pilot.
3. If your gas valve shuts off the gas (listen for a click) in 25 seconds or less, the thermocouple is bad. 25-60 seconds is okay.
 
Thank you all for responding! :)
jimbo said:
Are you in a very hot climate ( that could be almost anyplace right now!) and is the water heater in the attic?
Click to expand...
No, and the water heater is in the cool basement.

Peanut9199 said:
I had a problem before where the supply line was not large enough for everything it was supplying and when another unit turned on it robbed gas from everything else and the pilot light would go out.
Click to expand...
I think I'm good. I have a 1" line coming in, then it's reduced at the furnace, water heater, and stove. Plus I fired up all the burners on the stove top to try killing the water heater pilot, but it stayed lit.


master plumber mark said:
you have not given anyone much info to go on...
Click to expand...
AO Smith FSG 40 232, Natural Gas
Just turned 10 years old.
I guess I needa fork. :(

Verdeboy said:
...Try this test:
1.Turn down thermostat. Leave gas valve on.
2. Blow out the pilot.
3. If your gas valve shuts off the gas (listen for a click) in 25 seconds or less, the thermocouple is bad. 25-60 seconds is okay.
Click to expand...
85 seconds to the "click". What does that mean?
 
If the pilot flame is good / strong then you could try another thermocouple in the event the one you installed is defective but this is a 1 in a million chance.

Most likely you will need to replace the gas valve.
 
I still think replacment is the way to.If you install a new control then tank
starts leaking a month later you will be replacing it anyway.Plus with a
new w/h you get a warrenty and up to date w/h.
 
I agree with HJ. Your thermocouple is fine. Now get that cleaning wire (broach) and ream out the pilot orifice. You've got ten years of carbon build-up in there.
 
Last edited:
Always Learning said:
AO Smith FSG 40 232, Natural Gas
Just turned 10 years old.
I guess I needa fork. :(
Click to expand...

You just ain't payin' attention.:D
 
Thank you all for the advice. :)

I've gotten out once since y'all chimed-in to look at new water heaters and only found "Richmonad" brand at the local big box. Y'all probably have your favorite brand or two. Do you mind sharing some of the better brands? Or some of the lower end brands I might steer clear of? :)
 
Richmond is made by Rheem.

i've installed mostly rheem for the last fifteen years, for what that's worth...
 
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