Combustion chamber draws air from room
Bradford White has FVIR resistant: Read
Flammable vapor ignition retardation system
Water heater combustion draws air into combustion chamber through air intake.
Water heater vent pipe to outdoors creates natural draft upward that pulls air into combustion chamber.
Air enters combustion chamber.
If air contains flammable vapors such as gasoline, then water heater burner ignites the vapor.
If unchecked, the ignition inside water heater will spread into surrounding room causing flashover or explosion that will kill you and burn down house.
When vapor ignites inside combustion chamber, the FV system senses very high heat and immediately shuts off air supply to combustion chamber.
This prevents flashover or explosion inside room.
Insurance company property and casualty losses prompted FV safety mandate.
Each water heater manufacturer is responsible for developing FVIR system.
Rheem developed system with glass vial that shatters in event of FV event.
Causes:
Exposure to flammable vapors, inadequate air supply, exposure to common household chemicals, clogged air intake, water heater dropped, vent pipe blocked, too many elbows in vent
 | TRD
glass vial is broken What to look for on Rheem, Ruud, Richmond, GE heaters |
When water heater experiences FV flammable vapor event, the glass vial breaks, causing spring door to snap closed cutting off air to combustion.
On Rheem/Ruud/Richmond/GE, if glass vial breaks, you need a new tank. Or Rheem or GE may send you part. Or, in case water heater is still under warranty, return heater to place of purchase for exchange.
Cause for FV event must be resolved before putting heater back into service.
Read manual and observe cautions, advisories, and maintenance shown in product manual.
FV water heaters are evolving rapidly. Information given here can be different than your specific model
When glass vial breaks, the air is shut off to combustion chamber
FV event is caused when Flammable Vapors enter water heater. Tripped FV helps prevents flashover, fire and explosion inside house.
 Larger image | Example illustration showing air intake and air shut off Other water heaters have air intake located on bottom Each model and brand water heater can vary as FVIR prevention evolves rapidly Water heaters rated over 65,000 BTU do not have FV system. Tankless water heaters do not have FV system. Space heater, open fireplace, gas logs etc do not have flammable protection and each item listed above can ignite vapors and kill you if precautions are not taken. |
1) On Rheem, Ruud, Richmond, GE heaters, look for signs of shattered glass on combustion floor.
2) Symptons by type of gas control: With Robert-Shaw and White Rodgers gas control valve: If pilot light stays on without problems as long as gas valve is in PILOT position, but you then turn to ON position and main burner flutters and disappears within 30 seconds then good chance TRD is tripped.'
With digital-type Honeywell gas control and White Rodgers Intellivent gas controls, there are wires connecting combustion chamber and gas control that will shut off gas to burner and pilot. Pilot will not light. Burner will not light.
3) Caution: Same symptoms can also be bad gas control, low gas pressure, or clogged air intake.
Inspect if air shut-off baffle is tripped upward. Inspect for broken glass. Clean air intake. Avoid dusty atmospheres. If water heater brand is not shown on this page, consult manual for FV information.
Water heater manufacturers
4) If pilot will NOT light, and there is NO gas available, then ECO can be tripped. Check manual for ECO. Some ECO/TCOs are small button located on front of combustion chamber: this configuration is re-settable after overheating problem is repaired (clean combustion parts and air intake). Some ECOs are located inside gas control thermostat. ECO inside gas control is single-use, and gas control valve must be replaced. Consult manual. Follow maintenance schedule shown in manual for cleaning combustion parts. Test ECO
5) If pilot will not stay lit, then thermocouple might be bad. Test thermocouple.
Read: pilot will not stay lit
Solutions
Solution 1: Call Rheem/ or GE or manufacturer of your tank:Rheem, Richmond, Ruud, GE water heater: Gather information from label on side of tank, then contact Rheem and ask for glass vial, and other affected parts.
GE chat
Contact Rheem
Read product manual for advisories about warranty.
Other brands: Call Manufacturer and ask for replacement parts and repair steps, and read manual for advisories.
FVIR systems are rapidly evolving, and manufacturer will have current solution which might reqire water heater replacement.
Rheem warranty and extended warranty appear to be pro-rated and say: 'the limit of liability is reached when the repairs/replacement equal the replacement cost of 'like and kind' equipment during the term of the agreement.
Follow prevention steps shown below.
Water heater manufacturers
Solution 2: Return water heater to box store where puurchased:If you bought GE water heater at Home Depot, they will exchange for new heater
Replace
How to install gas water heater
Solution 3: Replace heaterRheem, Richmond, Ruud, GE water heater must be replaced unless Rheem / GE can ship glass vial.
Other brands water heater also require replacement.
Install new heater and follow prevention steps below.
How to install gas water heater
How to recycle old water heater
Flame arrestor screen located under glass vial
Before repairs are madeClean flame arrestor so air can enter combustion chamber.
Use air compressor and duster.
Clean air intake located on side -or- located bottom of heater. How to clean air intake
If air intake is located on bottom of water heater, then water heater has 3 legs, and screen on bottom of tank is could be difficult to clean without removing burner.
Clean burner and clean combustion chamber. How to clean combustion chamber
Remove all flammables and household chemicals from area.
Move water heater out of dusty, dirty environement, and set 18" off floor
Inspect vent pipe and check draft. Vent test
Off-code repair
Full image with words
Solution 4: Repair work-around: Bend part using pliersWarning: NOT code. NOT recommended. VOIDS warranty. UNsafe since FV system is no longer operable.
How to repair TRD
How to repair Rheem FVIR: If you cannot buy the glass vile that holds spring loaded door. You can by-pass device by removing burner assembly and using needle nose pliers. Reach in and bend metal bracket that held glass vile. Bend it so it holds open spring loaded combustion air door.
Next clean out the air intake, clean flame arrestor screen that filters incoming air, and follow prevention shown below. FVIR/TRD water heaters need plenty of clean air, and proper venting.
Your heater should now stay lit.
Solution 5: Repair work-around using ordinary fuse or nailWarning: NOT code
Don't do this.
Insert cartridge type fuse (short variety) to replace glass vial
This
is not a game. New heater costs a few hundred dollars. Hospitals, lost wages, lost careers, funerals, burned-down homes cost more.
I personally knew two fellows who were killed while laying floor tile in Chicago in 1978. They were using the old petroleum-based floor adhesive (now outlawed). Water heater ignited floor adhesive and conflagration killed both young men.
Recently, the local Lowes manager told me he had a friend who lost both legs. The fellow smelled gas. Instead of leaving the building and calling gas company, he removed front panel off water heater. The explosion and fire caused life-altering injuries. His action by-passed the FVIR safety feature by removing front cover.
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| How to access FVIR/TRD. Take photos of everything for easy re-assembly. 1) Remove wires as needed from Gas control valve and ECO located on combustion door 2) Disconnect Thermocouple, Manifold tube, and Pilot tube from bottom of Gas control. Notice these connections are not overtightened and do not require pipe sealant. 3) Gas controls vary. Manifold and pilot tubes on LP gas heater are reverse thread. Some thermocouples are reverse thread. 4) Burner door is held with 2-4 screws and may require replaceable gasket or sealant. Be careful with gasket so it can be reused. 5) Pull out burner assembly. It will fit under or into a slot. 6) Reassemble after repair. Do not overtighten connections. Thermocouple is usually finger-tight + 1/4 turn. 7) Use soapy water and check manifold and pilot tube connections for gas leak. | DO NOT remove or loosen the combustion door without turning off gas. Larger image Product manual has diagrams and advisories Example combustion cover removal for Bradford White Troubleshoot gas water heater |
1) Do not store gasoline in open container.
Caused by overheating inside combustion chamber
ADEQUATE FRESH CLEAN AIR
1) Do not store gasoline or flammables near water heater. Keep gasoline, kerosene in closed containers.
2) Avoid dusty atmospheres and give water heater adequate fresh air supply
3) Turn off water heater when using oil-paints, varnish, spray propellants, shellac, WD-40, thinners, lacquors, hair spray, gasoline, solvents, flammable cleaners, contact cement. Read product label to identify flammables.
4) Install water heater 18" off floor since gasoline vapors gather close to floor. Other flammable vapors do not gather close to floor.
5) Read product labels for flammability and advisories
6) Avoid storing or using chemicals in same room
7) Craft sprays and home project materials are flammable. Read labels.
8) Read manual and follow yearly maintenance schedule for cleaning air intake and combustion parts.
9) Make sure vent pipes are working and that combustion parts and top of water heater are not sooty.
10) Don't drop water heater
 3) Turn off water heater burner and pilot when using flammables |
 4) Set water heater 18" off ground |
 5) Read product labels for flammable warning: shellac, Kilz, lacquer, varnish, craft spray, floor paint, spray paint, solvents, accelerants, cleaners, etc |
 6) Clean air intake regularly |
2) Avoid dusty atmospheres and give water heater adequate fresh air supply
5) Read label for flammable warnings
See if smoke drafts immediately upward.
The smoke should not linger. It should draw upwards quickly.
If vent does not have draft or if furnace vent is blowing out of water heater vent each time furnace turns on, then vent pipes must be repaired.
All gas appliances must vent out of house to avoid CO poisoning.
Read checking the draft
| 8) Read manual for advisories, warranty and maintenance schedule. Repurpose old water heater: Recycle old water heater Tempering tank Solar water heater |  9) Don't drop water heater. TRD/FVIR will break |
AO Smith FVIR water heater uses Cordite arrestor
Example 2011 manual
Example service manual 2006 Page 17-18
How to clean arrestor using vacuum and brush
Water heater cannot be put back into service if arresor is cracked.
Arrestor must be inspected,cleaned, and parts replaced as needed. Arrestor is not replaceable part.
 | AO SmithWater heater manufacturers Image showing 2006 AO Smith FV design. If FV event occurs, the arrestor screen is inspected for cracks. Then TCO is tested and replaced as needed. If screen is cracked, replace water heater. Otherwise, clean arrestor screen, remove flammable materials, and water heater is serviceable. 2006 design has Replaceable TCO shown Page 18 manual |
 Larger image |  Resettable TCO on front of combustion chamber Larger image | AO Smith2008-2010 design has resettable TCO located on front of water heater. If FV event causes TCO to trip, it can be easily reset. And then arrestor screen is cleaned with brush and compressed air, and then inspected for cracks. If arrestor screen is cracked, then replace water heater. Using water heater with cracked arrestor screen will void warranty. 2010 AO Smith has Honeywell electronic gas control valve, with wiring changes for resettable TCO |
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Resettable FVIR
Clear flammable vapors from area
Turn off power to water heater for 10 seconds
Within 10 seconds of restoring power, press both temperature adjust buttons simultaneously (blue and red triangles) until the green vacation LED begins to blink.
When Vacation begins to blink, replease temperature adjust buttons
Again, within 10 seconds, press both temperature adjust buttons simultaneously until the vacation LED is on steady without blinking ( 5 second delay)
Release temperature adjust buttons, the microprocessor will clear FVS lockout and normal operation will resume
AO Smith Effex water heater has resettable FVIR system
Same steps shown above are entered in control box located near top of heater.
Most water heaters need to be replaced 2012, but the manufacturers are working toward resettable FVIT.
And manufacturers have moved to conditional limited warranties that might require professional installation and yearly maintenance. Read the manual and specification sheet BEFORE buying. Call the manufacturer.
AO Smith Effex
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| AO Smith Effex has resettable FVIR Read review Effex Service Manual Same as Kenmore High efficiency, State high efficiency, and American high efficiency |  |
| Bradford White has FVIR resistant water heater 1) Flame arrestor has large openings that reduce chance of dust and lint causing problem. 2) Likelihood of dust and lint clogging flame arrestor is reduced by the height of combustion air inlet located on side of tank Read Defender FVIR heaters Review of Defender FVIR FVIR forum discussion Bradford White Icon gas control valve features |  |
| "In the case where trace amounts of flammable vapors are present in the air flowing into the combustion chamber, the vapors are harmlessly ignited by the burner / pilot flame. If flammable vapors are in sufficient quantity to prevent normal combustion, the burner/pilot flame is shut down. Should the flammable vapors continue to the burner, the flame arrestor plate prevents the flames from traveling backwards and igniting vapors outside of the combustion chamber. The calibrated, multipurpose thermal switch recognizes this and shuts down the pilot and main burner. This switch also deactivates the burner and pilot in the unlikely event of restricted airflow caused by severe lint, dust or oil accumulation on the arrestor plate." Water heater must be replaced after flammable vapor incident/ read Pg34 service manual Bradford White service manual In event of overheating, or thermal event, the ECO trips and can be reset after cause of overheating is repaired |
Designed to let air pass into combustion chamber.
But will 'prevent flames from traveling backwards through flame arrestor and outside water heater'
Read pdf
 | FVIR mandates were passed to reduce insurance casualty and property losses. Many household appliances can cause flashover and explosion of hydrocarbon fuels Fireplace Tankless water heater Hybrid electric water heater Oven Stove Space heater Gas logs Faulty wiring Tank-type gas water heaters are located in garages and storerooms where flammable vapor storage is probably more likely to happen. People are more likely to clean a paint brush using gasoline while in a garage, rather than in the kitchen or family room. |
 | If you smell gas Leave building immediately Do not turn on light switch. Do not stop to open windows Call gas company Gas is transparent but odorant is added so people can smell when gas is present. Illustration shows colored gas, but gas is transparent. LP gas hugs the floor and can fill a basement. Do not install LP gas water heater below grade (in basement). Smell close to the floor when LP gas is used. Natural gas rises. You can easily smell natural gas while standing. Install gas detector. |
