August, 2005

Inspection News and Views from the American Society of Home Inspectors

What is Different About FVIR Water Heaters?


This article is reprinted from the November 2003 ASHI Reporter.

To meet the American National Standards Institute’s (ANSI) new standard for gas water heaters, a slightly different gas water heater has hit the market. Though the change in the actual design of water heaters will differ somewhat from manufacturer to manufacturer, the objective is the same. That is to reduce the potential of fire or explosion from flammable vapors ignited by gas water heaters.

WaterHeater1.gifAs of July 1, 2003, 30, 40, and 50-gallon, gas-fired water heaters built for sale in the United Sates must include features that will resist the ignition of flammable vapors outside of the unit. Suppliers, in an effort to capitalize on the concerns of the changeover, including the increase in price, stocked up on the conventional models. As that stock runs out, the newer appliances will be sold. Some plumbing suppliers in my area, eastern Virginia, have depleted their inventory of conventional water heaters and are now delivering the new units. (Photo: The average person will likely see no difference in the FVIR Models. State water heater shown. Photo courtesy of the author.)

What’s changed  

I’ve installed conventional gas water heaters for more than 30 years, and I’ll confess I had some reservations about the change. To ease my angst, I spent a little time checking out several of the major brands and reading articles on the changes. Recently I installed my first Flammable Vapor Ignition Resistant (FVIR) unit, and my first experience was a positive one. Piping changes—both gas and water and flue vent adjustments—were no more necessary than with any water heater I have replaced.

The main difference in FVIR water heaters can be found at the combustion chamber. A device called an arrestor plate is now installed. The arrestor plate will allow flammable vapor along with the combustion air to be pulled through and ignited. But the plate keeps the flame from passing back through to the atmosphere. Another feature is a temperature sensor that recognizes the event and shuts off the burner as well.

The most visible change in the new water heaters is in the way the combustion air gets to the burner. At first sight, the average person will likely see no difference in the FVIR models. Closer inspection reveals combustion air intake openings in the jacket at the sides or the base of the water heaters.

Bradford White and Rheem water heaters have openings that extend from the left and right side of the jacket door. Water heaters made by the American Water Heater Company pull in air through the bottom, and State water heaters have a screen below the jacket door in the front of the unit.

Though conventional water heaters are opened to the atmosphere, the removal of the outer jacket door on the new heaters exposes a sealed inner combustion chamber door with an inspection port. A Piezo igniter, a mechanical or push button igniter like that found on some gas logs and barbeque grills, makes the opening of the combustion chamber unnecessary for lighting.

Manufacturers suggest that under normal conditions cleaning or maintenance of the air intakes will be unnecessary for the life of the water heater. Some do note that if extreme environments create the need for cleaning, it can be done with a shop vacuum cleaner or air compressor.

To help ease installer and technician fears, Rheem and Bradford White promote that many of their replacement parts are standard, off-the-shelf items. State promotes the simplicity of their parts replacement.

Inspecting the new water heaters

Unlike “Direct Vent” water heaters that bring in combustion air and discharge spent fuel through a sealed vent to the outside, these heaters use the air from the space in which it’s located for combustion. The current lines of FVIR water heaters I’ve checked out have top mounted draft hoods like the old gas-fired conventional water heaters we’ve come to know. Normal flue venting rules and concerns should still apply.

When inspecting these new water heaters, you still want to check the water and gas piping and, of course, the Temperature Pressure Relief Valve. But when it comes to inspecting the characteristics of the flame or the quality of the ignition, do this through the view-port. Rust flakes, soot, and flame conditions that would cause you to write up a conventional water heater should be noted with the FVIR type water heaters as well.

As a professional plumber, gas fitter and HVAC contractor, I am opposed to any nonqualified person working on a gas appliance. Gas can be unforgiving. A mistake can bring terrible consequences. With this in mind, if the view-port is dirty, preventing proper inspection of the combustion chamber, note what you can see and what you cannot see. I would discourage the home inspector from opening the inner door to clean the view-port glass or to peek inside.

Should the door gasket become damaged with the removal of the inner door, the average home inspector will not have the parts needed to reseal it. Write it up, but leave it alone, and recommend that a qualified water heater contractor service the appliance.

Information for clients and real estate agents

I provide training for real estate agents in my area. During the past few months, I’ve been informing them that replacing an existing conventional gas-fired water heater with the new FVIR water heater will cost as much as 50 to 60 percent more than in the past. Installation costs should go unchanged; the increase in price is due to the cost of the appliance itself. Home inspectors who provide “cost to cure” information should keep this in mind when talking with clients.

As you encounter the new water heaters, locate and point out to your client where air enters. Encourage them to keep this area clear, and suggest they not perform activities around the unit that might create excessive amounts of dust and grime.
A recent tragedy in my hometown involving what was reported to be the
ignition of gasoline by a compressor emphasizes the fact that no flammable liquids (vapors) should be kept near any appliance. Although the new design is intended to help prevent accidental ignition of flammable vapors, continue to warn your clients about storing flammables in the vicinity of the appliance.

More Changes for Water Heaters

According to an article in the April 2003 “Plumbing and Heating Contractor News” over the next two years, all residential gas-fired water heaters will make the FVIR change.

The article also noted that energy standards would soon change for both gas and electric water heaters. An HCFC (hydrochloroflorocarbon) foam band may require an adjustment of water heater dimensions to accommodate thicker insulation around the tank and better emissions standards may have an effect on what some of us will soon see in water heaters as well.