The Tank › Blown Flue Baffle
- May 4, 2009 at 1:44 am #11323
Hello everyone. I’ve been reading this board all day while troubleshooting my water heater and thought I would post the day’s findings (with pictures!) to help out anyone else who may have this problem in the future.
Water Heater = A.O. Smith
Model = FGR 40 118D (40 Gallon)
Serial# = GE92-1087741-118D (May 1992)
Type = Natural Gas
Yesterday morning the wife complains after taking her morning shower that there is no hot water. I go out to the garage to inspect. We have owned the house for 3 years and I have never done more than look at the water heater before. So I open up both (inner and outer) doors and sure enough, the pilot light is out. No big deal. Turn off the gas, turn down the thermostat, turn gas back to pilot, push in the pilot button, hear the gas flow, light a match, light the pilot, wait for thermocouple to heat up, turn gas all the way on, turn thermostat back up, burner lights, and all is good in the world once again.
Or so I think. Later that day, no hot water again. Inspect again. Pilot light is out again. Repeat process. No problems lighting pilot or burner. But after the tank has been on for a while, the pilot goes back out again.
So now I have to figure out what’s going on. Test the voltages for the thermocouple output test (13mv) and the safety drop out test (10mv). Both are a little low (11mv/9mv respectively) but not too bad. Replace thermocouple anyway. No change.
So now what? I check in the air intake. Its a little dusty, but not bad. Clean it out. Exhaust vent looks fine too. Looking inside the combustion chamber I can kind of glimpse something that shrapnel (See pic)May 4, 2009 at 1:45 am #11324
Next I stick my hand up inside the flue and sure enough, pieces of metal crumble in my hands. I pull them out and look at them:May 4, 2009 at 1:46 am #11325
Since I can’t see inside, I used the camera to get a better look:May 4, 2009 at 2:02 am #11326
Wow, that sucks! I just wrote a nice long summary, tried to post it, and got denied because it was too big. That wouldn’t be such big deal if hitting the back button didn’t cause everything I wrote to disappear into cyberspace =(
Alright, so this is the short(er) version. Obviously my flue baffle is rusted out and needs to be replaced, but is that really the cause of the pilot light going out? I watched it and both the pilot light and burner flame extinguish at the same time, more like a cut-off is killing them. Any thoughts?May 4, 2009 at 2:17 am #11327
One last thing. Here is a link to a short video I took of the pilot light staying lit when I manually turn the thermostat down (killing the burner flame) and back up a few times:
Doesn’t this show that something is definitely killing the supplied gas (since its not the burner extinguishing that’s the culprit)?May 4, 2009 at 9:52 pm #11335EjParticipant
The FGR 40’s number 1 reason for pilot drop outs is a dirty flame arrestor. In fact I cleaned 2 today for this very same problem. I Agree you need a new baffle but unless you are seeing the burner extinguish your pilot which at looking at your video isn’t the case. Make sure the radiation shield is at least 1/2 off the bottom of the heater all the way around and clean the black intake screen along with the underside of the flame arrestor. Search my post for methods on cleaning this.
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