A.O. Smith Gas Hot Water Heater Flame Sensor Repair
a couple days ago our hot water heater became just a cold water storage tank. Our A.O. Smith GCV 40 100 HWH
had been functioning perfectly since we acquired it with the house in 2008. Being a gas hot water heater, I was a bit
about messing with it since gas has a way of exploding at the most inconvenient times - like when your face is staring into
a burner chamber. I attack electrical problems with near-reckless abandon from having dealt with AC and DC supplies and
controls for nearly five decades (I turn 58 in August). Nevertheless, last December when our
Trane VX95 gas furnace decided
it was time to be a cold air storage container, I sought advice on the Internet for how to exact a repair - and found it.
The problem was a dirty flame sensor element. I cleaned it per recommendation and it has work just fine ever since. I wondered,
therefore, whether the gas hot water heater might be experiencing the same phenomenon. After all, it was exhibiting the
same sort of behavior where the burner would initially ignite and then shut off after a couple seconds. Spoiler alert: It
was the sensor.
off the gas supply valve and letting the residual gas in the line dissipate, I removed the three fittings on the bottom
of the control mechanism and unplugged the ignitor wire. Next, the burner assembly was removed from the burner chamber. The
photo shows some metal
scale accumulation on the top surface, but an inspection of the bottom of the water tank did not reveal any ominous looking
areas. I vacuumed the burner assembly thoroughly and then cleaned everything with acetone. 600 grit wet/dry sandpaper was
used to carefully remove all the residue buildup off the flame sensor and other parts so that it looked almost like new
prior to being reinstalled.
replaced, gas turned on, and the pilot light re-lit. I crossed my fingers, clinched an appropriate amount, and turned the
temperature control to its normal position. Voila! The burner lit and stayed lit until the water was up to temperature.
Yea! I just saved $140 for a replacement burner assembly and, if a technician had to have been called, probably a couple
hundred bucks worth of labor. Update: I discovered after writing this that Lowes and Home Depot both
sell replacement thermocouple flame sensors for about $10, so if it happens again, I'll just replace
I pretty much live by the sage words of Red Green(aka Mr. Duct Tape), of Possum Lodge fame, "If the women don't find you handsome, they should
at least find you handy."
Go to 4:10 in the video
A huge collection of my 'Factoids' can be accessed from my 'Kirt's Cogitations'
table of contents.
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas
and reference material while performing my work as an RF system and circuit design engineer.
The Internet was still largely an unknown entity at the time and not much was available
in the form of WYSIWYG
All trademarks, copyrights, patents, and other rights of ownership to images and text
used on the RF Cafe website are hereby acknowledged.