By Jim Olsztynski

Issue: 3/03

Rheem Water Heaters hosted the industry's trade press in a series of visits to its Montgomery, AL, facility in early Feb. to unveil the Rheem Guardian System, a new line of residential gas-fired, atmospheric water heaters specially designed to meet the new ANSI Standard governing flammable vapor ignition resistance (FVIR).

ANSI Z21.10.1-2001 goes into effect July 1, 2003, to address the problem caused by improper storage of gasoline or other flammable liquids near gas-fired water heaters. The new standard covers residential 30-, 40- and 50-gal. units.

To meet the new standard, any water heater produced on or after the effective date must be designed so it cannot ignite flammable vapors caused by spilled gasoline outside the unit. There is no retrofit provision, so existing installations will not be affected, and non-FVIR water heaters may continue to be sold and installed until inventory is depleted. Rheem's vice president of marketing, David Martin, estimated that will be around September of this year.

Rheem collaborated with other water heater manufacturers to develop FVIR technology as part of a Water Heater Joint Research and Development Consortium, although each company has its own proprietary design approach. All FVIR water heaters will include a flame arrestor plate to shield the burner and prevent its flame from spreading beyond the arrestor and igniting vapors outside the water heater. Rheem's Guardian System also includes an air shutoff system that cuts off both the air supply and gas supply in the event of a flammable vapor incident. This prevents vapors from continuing to burn inside the water heater's combustion chamber, which might overheat the unit.

Rheem also has incorporated design features to resist the detrimental effects of lint, dust and oil (LDO) on arrestor plate designs. The new ANSI Standard includes testing for reliability in high LDO environments. Rheem presents its Guardian System as maintenance-free, not requiring periodic cleaning of the arrestor plate.

Power-vented water heaters will come under the new standard as of July 1, 2004. Remaining models, including commercial water heaters, will have to comply as of July 1, 2005.

For more complete information about FVIR, visit PME's editorial archives for March 2003 and click on the article, "A New Design for Gas Water Heaters."

Jim Olsztynski is consulting editor for PME. He can be reached at