RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
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formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
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A.O. Smith Gas Hot Water Heater Flame Sensor Repair
Without warning, 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 trepidacious 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.
After turning 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.
Everything was 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 the sensor.
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