Rheem Flammable Vapor Sensor repeated lockouts

[GregN31]

Hello,
I have a Rheem Powervent water heater (gas) model 42VP40F (40 gallon) manufactured 05/2007.
Starting in the last year, the Flammable Vapor Sensor has started tripping intermittently.
The gas valve I have is a Robert Shaw with a manual red dial.
About a year ago we had one occurence and not knowing anything about it I called my plumber who came out and replaced the sensor.
The sensor itself is at the bottom of the water heater and is only about $20. Its carbon based I believe.
I don't believe it tested out of range but he replaced it anyway. The range Rheem said was 19,000 to 45,000 milliohms of resistance. The first one was in range but he replaced it anyway being so cheap.
That held up for several months. Beginning a few months ago it started tripping again.
This time I called Rheem, and they gave me some advice.
Every time it has gone off it has flased a code of 2 blinks, pause, 3 blinks.
The manual says about that:
"Lockout condition. FVD interface failure/miswiring (Flammable vapor sensor failure)".
There is also a code of 2 flash pause, 1 flash which is "Flammable Vapors Present". I have NEVER had that one.
It is always this 2 flash, 3 flash code.
The Rheem rep had me test the sensor, and I've done it many times now and it always tests in range. Right now its at 31,000 which is in range.
Every time it trips, and it happens sometimes daily now, it always is in range and fine.
To answer the obvious question, there are no flammable vapors I know of present, no gas, no paint, nothing different in this basement for the last several years, at least that I know of.
Whether there is some small leak of gas or something hydrocarbon I don't know of is possible, but I'm unaware.
It is not wet in this basement, the sensor itself is not wet or subjected to water.
The Rheem rep told me that if this is happening, and the sensor itself tests in range of resistance, that only leaves one thing, and that's the actual gas valve. They don't use this Robert Shaw anymore, so they told me I'd have to buy a new one with the whole burner assembly.
What they are saying is that the only thing left is that my gas valve unit is going bonkers.
This whole kit is $250-$350 plus labor to install it, so I would guess I'm in the $500 range all told.
For an 8 year old water heater, I have to wonder if I shouldn't replace it.
I will replace it if I have to but I'm wondering:
1. Does anyone have any other ideas?
2. Should I buy another vapor sensor for $20 and throw it on for kicks and see if it resolves it for another several months?
3. Any idea what could be making this go off if there is no flammable vapors present? It doesn't look immediately obvious that anything is clogged, but I could vacuum in the fresh air screen and inside the water heater a little bit I guess.
4. If the sensor is testing in range, is all that is left is the controller?

I'm ok with replacing the water heater I guess, I just am wanting to be sure and a little concerned of that small chance there is something causing this I'm not addressing and replacing the water heater will just have another water heater tripping. Like I said I don't believe I have any vapors present...but who knows.
Although they said if there were it should be damaging the sensor and making it then test out or range for resistance, so there probably really isn't any.

Oh, every time this thing locks me out with the flashing code, I simply do the reset procedure which is to turn off the power vent, then turn it back on and then turn the red dial on the controller to hot and cold 6 times in quick succession. Every time it cures the lockout and the pilot fires right up and I'm fine for several hours or a few days again. Its just starting to happen about once a day now.

Rheem did tell me there were some Robert Shaw valves subject to a recall I think it was but mine was made after, although they have switched to an entirely new assembly with a electronic valve, I think a Honeywell now.

Thanks,
Greg

 

[Master Plumber Mark]

Rheem had terrible troubles with that robert shaw valve....
I have one new in my office that has been sitting on the shelf in its original box since probably 2005
that was a replacement valve they sent me for a brand new heater we had installed a few weeks earlier..

I decided to just tear out the whole heater and install a Bradfrod White instead of messing with it and
I am glad I went the extra mile
..

your heater is out of parts warranty and I doube\t they will send you a upgrade kit to the new valve...
which they should do but dont have to.

 

[Sponsor]

 

[Dennis Vinas]

Hello,
I have a Rheem Powervent water heater (gas) model 42VP40F (40 gallon) manufactured 05/2007.
Starting in the last year, the Flammable Vapor Sensor has started tripping intermittently.
The gas valve I have is a Robert Shaw with a manual red dial.
About a year ago we had one occurence and not knowing anything about it I called my plumber who came out and replaced the sensor.
The sensor itself is at the bottom of the water heater and is only about $20. Its carbon based I believe.
I don't believe it tested out of range but he replaced it anyway. The range Rheem said was 19,000 to 45,000 milliohms of resistance. The first one was in range but he replaced it anyway being so cheap.
That held up for several months. Beginning a few months ago it started tripping again.
This time I called Rheem, and they gave me some advice.
Every time it has gone off it has flased a code of 2 blinks, pause, 3 blinks.
The manual says about that:
"Lockout condition. FVD interface failure/miswiring (Flammable vapor sensor failure)".
There is also a code of 2 flash pause, 1 flash which is "Flammable Vapors Present". I have NEVER had that one.
It is always this 2 flash, 3 flash code.
The Rheem rep had me test the sensor, and I've done it many times now and it always tests in range. Right now its at 31,000 which is in range.
Every time it trips, and it happens sometimes daily now, it always is in range and fine.
To answer the obvious question, there are no flammable vapors I know of present, no gas, no paint, nothing different in this basement for the last several years, at least that I know of.
Whether there is some small leak of gas or something hydrocarbon I don't know of is possible, but I'm unaware.
It is not wet in this basement, the sensor itself is not wet or subjected to water.
The Rheem rep told me that if this is happening, and the sensor itself tests in range of resistance, that only leaves one thing, and that's the actual gas valve. They don't use this Robert Shaw anymore, so they told me I'd have to buy a new one with the whole burner assembly.
What they are saying is that the only thing left is that my gas valve unit is going bonkers.
This whole kit is $250-$350 plus labor to install it, so I would guess I'm in the $500 range all told.
For an 8 year old water heater, I have to wonder if I shouldn't replace it.
I will replace it if I have to but I'm wondering:
1. Does anyone have any other ideas?
2. Should I buy another vapor sensor for $20 and throw it on for kicks and see if it resolves it for another several months?
3. Any idea what could be making this go off if there is no flammable vapors present? It doesn't look immediately obvious that anything is clogged, but I could vacuum in the fresh air screen and inside the water heater a little bit I guess.
4. If the sensor is testing in range, is all that is left is the controller?

I'm ok with replacing the water heater I guess, I just am wanting to be sure and a little concerned of that small chance there is something causing this I'm not addressing and replacing the water heater will just have another water heater tripping. Like I said I don't believe I have any vapors present...but who knows.
Although they said if there were it should be damaging the sensor and making it then test out or range for resistance, so there probably really isn't any.

Oh, every time this thing locks me out with the flashing code, I simply do the reset procedure which is to turn off the power vent, then turn it back on and then turn the red dial on the controller to hot and cold 6 times in quick succession. Every time it cures the lockout and the pilot fires right up and I'm fine for several hours or a few days again. Its just starting to happen about once a day now.

Rheem did tell me there were some Robert Shaw valves subject to a recall I think it was but mine was made after, although they have switched to an entirely new assembly with a electronic valve, I think a Honeywell now.

Thanks,
Greg

I purchased a "Performance Platinum 40 Gal Short 12 Year 40,000 BTU Natural Gas ENERGY STAR Tank Water Heater with WiFi Module Included" from HD in Oct2019. After a week of normal operation, it quit heating up water and I found out that it was in a lockout mode. (LED indicator flashes 7 times, pause, etc. Digging into the manual, the 7 flashes indicates that the system has detected flammable vapor or absent flammable vapor sensor. Rheem tech support walked me through resetting the unit successfully but 7 flashes re-occurred after 15 minutes. They sent me a replacement Flammable Vapor Sensor...failed after a week with the same LED indication. On my third Flammable Sensor, I used a long pair of wires to position the new sensor on a counter top, about 3 to 4 feet away from the heater...that failed after a week as well.
The water heater is mounted on a drip pan in rather large mezzanine where our break area is located...totally open space, no enclosure and well ventilated so the probability of flammable gas, paint fumes circulating around is remote. I don't have any leaks from the gas valve so I figured the sensor I have been buying are defective.
I got tired of replacing the sensor every week so I bypassed the sensing device with a 20Kohm resistor and my heater has worked flawlessly ever since.