 Rheem FVIR repair requires part Some gas control valves can be reset after FV lockout Gas water heater should sit 18" above floor |
Who
makes the most easily resettable FVIR: Who makes the best Flammable vapor system: Applies to residential gas water heaters/ does not apply to commercial heaters or electric heaters  Search    Search using google with ads    |
 Difference between FVIR vs FV
sensorThe FV sensor is located on front of many water heaters today. The sensor will trip if it senses gasoline vapors in the air. It does not respond to other types of flammable vapors. Research shows that gasoline is the most common cause of fire or explosion caused by water heater. The FV sensor is easily tested using multimeter and easily replaced by plugging new one into terminal slots. How-to-test-FV-sensor-2.pdf  Flammable-vapor-sensor explained .pdfThe FVIR is different than the FV sensor. The FVIR flammable vapor ignition system is located inside the heater. FVIR is mandated by congress. The purpose of the FVIR is to retard the acceleration of a fire that is ignited inside the water heater ... for example, if you are using a lacquer-base substance in enclosed area near the water heater, the vapors will be drawn into the combustion chamber by normal operation of water heater sucking in air to support combustion. The pilot flame or burner can ignite the lacquer vapors. After ignition the fire can accelerate back into the room where you are working, causing explosion or fire. The FVIR system is designed to respond to the the ignition, and shut off access between the combustion chamber and the room.  Bradford White and AO Smith both use a screen-like material that is designed to let air passively enter the combustion chamber to support ordinary operation of heater ... but if there is an explosion outward, the screen limits the acceleration of flames ... it stops or retards the fire from going back into room. The Rheem system does not use a screen. Instead they use a glass vial that breaks under high heat and causes a damper to close ... the glass vial is difficult to replace, unlike the screen system that needs no replacement ... that is unless Rheem changed systems, but the lack of transparency by Rheem makes everybody a little dumber because we have to guess... which is reason enough not to recommend Rheem. |
Best: AO Smith has easiest FVIR with fairly simple DIY repair. Brands using same design include State, Whirlpool, Kenmore, Reliance, American, Craftmaster etc. How to repair AO Smith FVIR Worst: Rheem makes the hardest, requiring disassembly and replacement part, including Richmond, GE, Reliant How to repair Rheem FVIR Good: Bradford White makes a system that resists FV problems, but is in the middle for ease of DIY repair and requires disassembly. How to repair Bradford White FVIR Flame lock cleaning .pdf Resources: Troubleshoot FVIR for each manufacturer Troubleshoot gas control valve thermostats Which is best gas water heater Old gas water heaters had no flammable vapor protection. Gasoline fumes would be sucked into burner and fumes would ignite. Sometimes there would be whoomph sound without further ignition of vapors in the room. Other times, there would be enough flammable vapor accelerating in flame that entire room would explode into a fireball, killing occupants and burning down house. Insurance company losses caused government to mandate water heater companies invent and implement FV systems. Other sources of ignition Tankless gas water heaters have no FVIR safety feature. Likewise, electric heat pump or hybrid water heaters have no protection. Nor does a fireplace, candle, space heater etc have such protection. Do not use flammable vapors inside enclosed room. Electric vs Gas Regular tank-type electric will generally not pose FV danger, unless there is electrical short. Flammable vapors, such as natural gas, are lighter that air and rise, while other flammable vapors such as propane and gasoline are heavier than air and fall to the floor. Local code prohibits installation of propane appliance below grade (basement) because gas leak can fill space with explosive vapor. |
 Raise water heater 18" off floor to avoid flood damage and flammable vapors Buy: Water heater stand |
4) Flammable vapor
Lockout varies by brand, year and model. When lighting water heater, if you have NO gas or pilot light but burner goes out when knob turned to ON ... then FV system is suspect. Some water heaters have FV system that is tripped by variety of different problems including flammable vapors. a) Push in TCO located on front of combustion chamber Troubleshoot TCO. b) Keep air intake screen, or flame arrestor screen clean. Dust and dirt can clog screen. Install heater in clean environment free from dust and chemicals. Laundry room, craft room, shop, chemical store room are not good location for FV water heater. When air intake is clogged, vent is obstructed, or incoming air supply is reduced, the air flow slows down. Same amount of gas is being burned but heat is retained inside combustion chamber instead of venting up flue. The overheating trips TCO and can trip FV system. Solution for FV lockout event varies by brand and model, and by gas control valve. Try cleaning arrestor screen first. Push in TCO reset on front of combustion chamber. Gas control valve may need to be replaced. FV sensor may need to be replaced. Part replacement depends on model and brand. c) Keep combustion parts and chamber clean. Lazy yellow flame, instead of clear blue flame, and sooting on the burner surface indicate incomplete combustion. Explosive gas can accumulate. Can trip FVIR. d) To prevent FV lockout and combustion problems: Perform maintenance shown in product manual, and keep air intake clean, allow plenty of fresh air, avoid dusty-dirty environments, and avoid flammable vapors. Help prevent FVIR event by installing gas water heater at least 18" off the floor. #1) Make sure there is adequate fresh air, and that air is clean and list free, and does not have trace chemicals. #2) Always turn off gas to water heater when painting with oil-base paint or oil-base varnish etc, and when cleaning with solvent-based products, and when pouring gasoline etc. For example when storing gasoline near water heater, the water heater should sit minimum 18" off floor, gasoline should be tightly capped, and do not pour gas to fill gas tank in same room as water heater or other gas appliance. |
 Gas appliance can ignite flammable vapors |
FVIR is flammable
vapor ignition resistance Resistance means the system will resist ignition of flammable vapors... but not 100% guarantee Gas water heater FV guidelines 1) understand FV lockout Troubleshoot FVIR 2) correctly install product (clean environment, plenty of fresh air) How to install gas water heater 2) regular maintenance to avoid problems How to clean combustion chamber 3) access to service manuals from manufacturer gas water heater troubleshoot manuals 4) turn off gas water heater when working with flammable vapors, 5) install electric water heater if you have high risk environment such as workshop for race cars, cleaning solvents, paint & lacquer, or have a dusty dirty environment (laundry room, attic, crawlspace etc) How to install electric water heater Resources How to troubleshoot gas water heater How to install gas water heater How dangerous is gasoline and gas water heater |
 Arrestor screen stops flames from spreading |
Understand lockout: There are 3 basic types of lockout. 1) First one is overheated combustion chamber due to inadequate air draw, improper installation, dirty dusty environment that clogs air intake screen, lack of proper venting, dirty combustion parts from lack of cleaning or maintenance etc. The flame begins to turn yellow instead of crisp blue... the venting of gas byproduct slows, yet same amount of fuel is being burned.... the combustion chamber overheats. Result lockout. 2) Second is actual flammable vapor sucked into combustion chamber that causes ignition of fuel and overheated combustion chamber. Most instances require cleaning, and/or part replacement.... but actual repair steps vary by model, age and brand water heater since the FVIR systems have evolved over the years since FV mandates came into effect. |
 Resource: example service manual for Intellivent: AO Smith Intellivent troubleshoot and FVIR test/ pdf Troubleshoot intellivent gas control valve |
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 Thermostat probe and ECO on gas control valve thermostat |
ECO and thermostats Thermostat on gas water heater is built into the gas control valve temperature probe. Normally this is a single use item... so if water is overheated inside tank because the thermostat has gone bad, then the ECO trips, and gas control valve must be replaced. Things that can affect failure of thermostat include age, defective manufacture, build-up of sediment etc. Resource: How to replace thermostat or gas control valve on gas water heater |
 TCO thermal cut off located front of combustion chamber |
TCO TCO thermal cut off is a resettable thermal switch located on front of combustion chamber that can be reset after some high temperature events inside the combustion chamber. TCO trips when combustion chamber exceeds temperature set point. One thing that would cause the thermal switch to trip is overheated combustion chamber because air intake screen is clogged with dust, or inadequate air supply. Dust clogs screen, so there is less air for venting, but same around of gas is burning inside combustion chamber, and overheating situation occurs. Resource: Troubleshoot incoming air supply |
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If
flammables materials are used, then all gas burning appliances in the
vicinity must be shut off and pilot lights extinguished. Open doors and
windows for ventilation while flammable substances are in use. The FV sensor is located inside a plastic case to keep it dry and clean... if the sensor is blocked, or has been covered with dust, leaves, water etc, it will not function. Replace part. The FV sensor must have continuity, so a small current of electricity can pass through the sensor and signal to gas control valve that all is ok. Buy: Flammable sensor kit |
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| 14 things needed for gas water heater & .pdf resources | |
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What you need for
operation of gas water heater. General troubleshoot 1) Basic parts and operation 2) Adequate incoming air supply ... issues: closed doors, tightly insulated house, very hot attic. 3) Adequate air supply getting to burner... issues: dirty vent screen, dirty environment, maintenance. 4) Thermal cutoff ... TCO ... issues: failed part, maintenance, vent. 5) Flammable vapor lockout .... issues: exposure to vapors, bad FV sensor, failed FV system, 6) Fuel supply to gas valve thermostat ... natural gas and propane are different ... issues: wrong gas, low pressure, moisture in pipe, undersized gas meter, supply line too small for BTU rating. 7) Gas valve thermostat regulates fuel supply ... issues: not enough gas, failed thermostat, failed gas control valve. 8) Fuel supply from thermostat to burner ... issues: maintenance, thermocouple-thermopile, gas control valve. 9) Clean and replace burner ... issue: periodic maintenance requires burner inspection, cleaning, and possible replacement 10) Functioning thermopile-thermocouple-pilot light ... issues: misalignment, failure of part. 11) Ignition of fuel supply by pilot light or hot surface igniter ... issues: pilot light, piezo igniter, electrode. 12) Power vent water heater troubleshoot ... issues: pressure switch, blower, blower sequence from gas control, outlet polarity 13) Venting combustion byproduct .... issues: vent in disrepair, other vents in house drawing air 14) Misc troubleshoot manuals |
 Inspect anode each 2-5 years Anode rod prevents tank from rusting Buy: Anode rods at Amazon Resources: Replace anode rod How to maintain water heater |
 Pressure gauge/ attach to water heater drain valve Pressure over 80 psi can damage water heater and household plumbing Buy: Water pressure gauge Temperature-pressure gauge Resources: Identify water heater valves Troubleshoot water pressure |
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