How to reset flammable vapor sensor on pvp50fw

SOURCE: ECO failure. Replaced the gas control thermostat & vapor sensor

It sounds like your gas/air mixture needs to be adjusted. The flame should have just the slightest amount of white, at the very tip. The rest should be evenly blue. There is an air vent adjustment in the line to the burner, right after the gas input.

SOURCE: What resistence does Flammable Vapor Sensor need

13 to 25 k ohms. Outside this range sensor is bad or has had contact with a flammable vapour or other non flammable chemicals.

SOURCE: I have a GPVH 40 100 AO smith hot water heater.The

AO smith manuals
http://www.hotwater.com/lit/im/r-gas.html

GPVH series manual
http://www.hotwater.com/lit/im/res_gas/315465-000.pdf
You can search the manual for FV

The FV sensor shorted because it detected flammable gas

Quote manual:
Flammable liquids (such as
gasoline, solvents, propane (LP or butane, etc.) and other substances
(such as adhesives, etc.) emit flammable vapors which can be ignited
by a gas water heater's hot surface igniter or main burner. The
resulting flashback and fire can cause death or serious burns to anyone
in the area. This water is equipped with a FV sensor for detecting the
presence of flammable vapors, see Figure 3. When the sensor detects
those vapors, the unit will shut down and not operate. Should this
happen, please refer to the troubleshooting guide on pages 28-30.

Troubleshoot step 14-15 says
replace the FV sensor
call tech assistance number that shows on water heater
AO Smith will refer you to a plumber
I don't believe homeowner can buy these parts due to Federal regulations
The shorted FV sensor probably saved you a flash-over
The cost of 2nd degree burns from a flash-over would be astronomical.
Fortunately you're ok, and the other folk in the room are ok.
In the old days.
Two guys I knew, winter 1978 Chicago, were laying VA tile using the black mastic.
They were killed and the house burned down because of the water heater.
Main office marked the event with a memo saying they still owed money on their account.

The only company with a re-settable FVIR that I'm aware right now is Bradford White
http://www.thetankatwaterheaterrescue.com/forums/forum3/2679.html
http://411plumb.com/bradford-white-defender-water-heater-review
Bradford White Defender FVIR is resettable without buying parts.

SOURCE: water hearer gas valve locked

If water heater has FV event, check your manual for re-setting procedure.
Look at label on side of tank for brand and model number of your water heater:
http://waterheatertimer.org/Water-heater-manufacturers.html
My understanding is that Bradford White has resettable FVIR but all other manufacturers require service technician for part replacement.

I have found one internet thread that covers do-it-yourself FV.
http://www.diychatroom.com/f7/rheem-hot-water-heater-pilot-burner-not-staying-lit-65755/

I also posted same question on water heater forums, and nobody will answer 'due to liability concerns.'
This leads me to believe there are serious safety issues that could lead to manufacturer and-or plumber liability since FV-lock-out mandates were written to reduce widespread insurance property and casualty losses.

SOURCE: my water heater say i have flammable vapors

Contact Rheem
http://www.rheem.com/Contact.aspx
1 800 432 8373
Locate product information on label on side of tank.

Typical manuals say if lockout occurs, then refer to gas valve codes and/or troubleshoot section:
http://globalimageserver.com/fetchDocument.aspx?id=a92c7d0e-8a95-48ba-8810-cd714f33d47a
http://globalimageserver.com/fetchDocument.aspx?id=80b1d50e-695f-49ac-9aae-3e9489ef1e5a

For example the manual says:
1. Verify no gasoline or flammable
vapors are present
2. Reset control using ON/OFF switch
on the gas control valve
3. Replace the flammable vapor sensor
http://waterheatertimer.org/images/Wiper-FVSensor-100.jpg
http://waterheatertimer.org/pdf/Rheem-Parts-Guide.pdf
http://waterheatertimer.org/pdf/Rheem-parts-list.pdf