# Hot Water Tank Flammable Vapor Sensor Lockout - A.O. Smith - Promax



## JerryKo

*Flammable vapour sensor*

i have 2 gas hot water heaters and one electric one in my 3 unit apt building.
the flammable vapour sensors have gone off 3 times each in my gas heaters in the last year... that is 6 sensors in a room that only has furnaces and hot water heaters, and 4 spare car tires. 
can i do anything to prevent this from happening? my plumber that comes in charges me around $170 each time he comes in, and he doesnt smell any flammable vapours, nor do I. the plumber doesnt know what the problem could be, he doesnt have these issues with the same hot water heaters in other buildings, just mine. it doesnt happen on the air heaters, just the hot water heaters.

any suggestions from anyone?


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## taviyo

*Pipe Dream*

JerrkyKo,

I believe that flammable vapors *are* causing your issue and your plumber is not helping you by doing a reset on your tanks. Plumbers like this guy make small fortunes on resetting these FV sensors as they are quick and easy fixes with a large house call bill. I would suggest finding someone more interested in fixing your real problem which is most likely a leaking gas fitting(s). At the very least, more properly ventilate your utility room and find out how to do the reset on your tanks yourself to save yourself the $170 headache.

T


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## gsoccer17jd

*FV Sensor Lockout*

Thanks for the info on resetting this sensor. After returning from vacation, the key board lit up w/3 lights after I attempted to turn the tank back on. The instruction manual stated it was a FV Sensor. I checked for gas leaks and all was OK. It worked great. I removed the switch and waited 90 minutes after setting it outside. - reassembled and it started on the 2nd attempt. Thanks again-!!!!!!:thumbsup:


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## DIY_novice

*Thank you TAVIYO*

Thank you TAVIYO !! Like you, I had been painting in my basement with oil-based paint (painting walls). I even had the windows open. Next day, no hot water! Not so helpful manual says to call qualified repair person. Yes, I can see point (it is a huge safety issue after all) . . . but still. Tried resetting myself by unplugging and plugging back in. Did not work. 

A friend found your post. You saved me $165 in labor ($65 "diagnostic charge" + minimum $100 trip charge). They also were quoting me an additional $100 to replace the FV Sensor. 

So THANK YOU again !! :thumbsup:


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## taviyo

DIY_novice said:


> A friend found your post. You saved me $165 in labor ($65 "diagnostic charge" + minimum $100 trip charge). They also were quoting me an additional $100 to replace the FV Sensor.


You can make the cheque out to taviyo PO Box 12345 :thumbup:

That's fantastic, I'm glad I posted this solution here as I'm sure there are alot more people that this has helped that haven't posted responses.


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## LarryM

DIY_novice said:


> Thank you TAVIYO !! Like you, I had been painting in my basement with oil-based paint (painting walls). I even had the windows open. Next day, no hot water! Not so helpful manual says to call qualified repair person. Yes, I can see point (it is a huge safety issue after all) . . . but still. Tried resetting myself by unplugging and plugging back in. Did not work.
> 
> A friend found your post. You saved me $165 in labor ($65 "diagnostic charge" + minimum $100 trip charge). They also were quoting me an additional $100 to replace the FV Sensor.
> 
> So THANK YOU again !! :thumbsup:


Well this is just fantastic :thumbup:
I also painted my basement with oil based paint on Sunday with the window open but it being early March I had to close the window because it is cold. I also cleaned my brush and roller in mineral spirits which I left in the pan for about 4 hours. (not the brush and roller)

Well come Tuesday morning no hot water...WTF
I get home tonight from work and school and still no hot water so I decided to read my owners manual after I see odd lights on the control panel. (the house stinks from the paint and mineral spirits)...the manual shows it is locked down because of the vapors :furious:

Glad I found this post. Last time I will use oil based paint and mineral spirits in the basement. Now I have to let everything air out and try the OPs method and pray I have hot water tomorrow night. Cold shower tomorrow morning 

Also found this on the internet. Helpful for AO Smith units with Intelli-Vent gas control 
1 Manual reset is accomplished by first, turning off power to the water heater for 10
seconds.
2 Restore the power to the water heater.
3 Within 10 seconds of restoring power, press the two temperature adjust buttons
simultaneously until the left (green) “Vacation” LED begins to blink (approx. 5 second
delay). Once the Vacation LED begins to blink, release both buttons.
4 Again, within 10 seconds, press both temperature adjust buttons simultaneously until the
Vacation LED is on steady (approx. 5 second delay).
5 Release the two buttons, the microcomputer will clear the FVS lock-out and normal
operation will then be restored.

​


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## LarryM

LarryM said:


> Well this is just fantastic :thumbup:
> I also painted my basement with oil based paint on Sunday with the window open but it being early March I had to close the window because it is cold. I also cleaned my brush and roller in mineral spirits which I left in the pan for about 4 hours. (not the brush and roller)
> 
> Well come Tuesday morning no hot water...WTF
> I get home tonight from work and school and still no hot water so I decided to read my owners manual after I see odd lights on the control panel. (the house stinks from the paint and mineral spirits)...the manual shows it is locked down because of the vapors :furious:
> 
> Glad I found this post. Last time I will use oil based paint and mineral spirits in the basement. Now I have to let everything air out and try the OPs method and pray I have hot water tomorrow night. Cold shower tomorrow morning
> 
> Also found this on the internet. Helpful for AO Smith units with Intelli-Vent gas control
> 1 Manual reset is accomplished by first, turning off power to the water heater for 10
> seconds.
> 2 Restore the power to the water heater.
> 3 Within 10 seconds of restoring power, press the two temperature adjust buttons
> simultaneously until the left (green) “Vacation” LED begins to blink (approx. 5 second
> delay). Once the Vacation LED begins to blink, release both buttons.
> 4 Again, within 10 seconds, press both temperature adjust buttons simultaneously until the
> Vacation LED is on steady (approx. 5 second delay).
> 5 Release the two buttons, the microcomputer will clear the FVS lock-out and normal
> operation will then be restored.
> 
> ​


FYI the method I listed with the reset steps worked perfectly


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## dotcom624

*Jury Rig instructions*

I had this happen to my A.O. Smith water heater this morning. My water softener discharge and drain are really close to the vapor sensor, and apparently got it wet. After trying in vain to reset it, I called the 800 number, and they said that moisture can kill it too. Bingo. I could not get the ohms under 120k (needs to be <70k to work) and that was in a perfectly clean environment. Bring the sensor out to my garage made it go >2000k, as high as my multimeter would go. I found the part locally, but I was too far away to get there tonight. 

So using the OP's advice, I "bypassed" it with a 10k ohm resistor (1/2 watt) from Radio Shack. I believe the OP stated you need a resistor >70k ohm, but <1,700k ohm. This is incorrect. 70k ohm is when it trips the sensor. It needs to be >5k ohm, but <70k ohm. I inferred that from the technical bulliten here http://www.hotwater.com/resources/literature/technical-bulletins/tb-a028-06/ ).

After jumpering the connection with the resistor, reset using the instructions, it fired right back up. Mind you, DO NOT do this for a long period of time. This is there for a reason, but as a quick fix, this works great. I'm picking up the part tomorrow, and I'm moving it further away from the water so it doesn't happen again. Perhaps protected by some surround that doesn't interfere with the opening. I DO NOT ADVOCATE THIS AS A PERMANENT FIX. Only as a temporary workaround.


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## new diy

Hey folks,

I've been searching for hours to no avail. So sorry for bringing back an old thread.

I'm gearing up to paint the floor in my basement. Knowing that I have a vapour sensor on hot water tank, I want to know what precautions I should take to prevent it from being tripped. 

At a glance, it doesn't seem easy to disconnect... It is a small white coloured piece of plastic with two saudered wires coming out the back of it connecting it to the main control terminal.

Any recommendations would be greatly appreciated. I'm considering wrapping it in a shopping bag, but not really sure if that is the kind of security that I want.

Has anyone gotten away with painting around their sensor? 

Thanks


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## KingRamsesII

*Water Heater Vapor sensor*

Hello all, So if you do the resistor fix do you take off vapor sensor and wire the two wires to the resistor? Thanks


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## Ghostmaker

Turn the gas and power off to your tank before you paint. Make sure you completely ventilate your basement prior to turning it back on. If you mess with the safety interlock you void your tank warranty.


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