Online News--A New Design For Gas Water Heaters
By Kelly Faloon
This summer marks the beginning of a new standard--and a new design--for gas water heaters. ANSI Z21.10.1-2001, which covers all gas-fired residential water heaters of 75,000 Btus or less manufactured in the United States, requires that the design of such water heaters "shall not ignite flammable vapors outside the water heater created by the spilling of...gasoline onto the floor."
Rollout begins July 1, 2003, with 30-, 40- and 50-gallon atmospherically vented water heaters. Phase 2 begins July 1, 2004, with 30-, 40- and 50-gallon power-vented heaters, and Phase 3 covers the remaining models, including commercial models, starting July 1, 2005. (Canada's Phase 1 will begin Jan. 1, 2004--six months behind the U.S. rollout.)
Efforts by the Water Heater Joint Research and Development Consortium resulted in a new technology. Arrestor plate technology is the linchpin of the first generation of flammable vapor ignition resistant (FVIR) water heaters. The consortium looked at a wide-range of technologies before settling on the arrestor plate as the best solution, said Jim Bienias, Rheem's senior product manager for residential products.
"If you go back into the history of water heaters, they've remained for the most part very reliable and unchanged for the past 40 to 50 years," he explained. "This design change is a dramatic difference for this industry."
Back in 1993, the Gas Appliance Manufacturers Association, in conjunction with its Water Heater Division members, sponsored a consumer awareness program designed to educate the public about a particular danger found in the home--flammable vapor ignition.
Flammable vapors are the byproduct of the evaporation of flammable liquids, such as gasoline, due to accidental spills or misuse in the home. When these vapors come in contact with an ignition source, they can cause a fire or explosion. Traditionally designed gas water heaters, which draw combustion air through vents at the bottom of the appliance, have occasionally ignited these vapors.
The U.S. Consumer Product Safety Commission in 1994 stated that the ignition of flammable vapors by gas-fired water heaters was associated with nearly 2,000 fires, resulting in 17 deaths and 316 injuries. However, only 5% of fires involving ignition of flammable vapors in homes were related to the gas water heaters. About 75% of these fires were due to spills of improperly stored gasoline or the improper use of gasoline.
The gas water heater industry, working with the CPSC and the American National Standards Institute, offered to voluntarily develop a permanent, technical solution to the flammable vapor ignition problem--the first redesign of water heaters in decades.
The new design calls for a sealed combustion chamber with an air inlet, where air flows through the arrestor plate, which is a perforated piece of steel. If any flammable vapors enter the combustion chamber, the arrestor plate, or flame arrestor, controls the burning of the vapors and prevents the flames from escaping the unit into the room, thus avoiding a fire or explosion. A bench standard that calls for protection of the water heater from lint, dust and oil, or LDO, was attached to the flammable vapor standard after it was determined in test studies conducted at Battelle Laboratories in Columbus, OH, that LDO contamination could be a problem.
However, each manufacturer has its own little spin on the design features. American Water Heater Co. was the pioneer with is Flame Guard system introduced in 1999, before the new ANSI standard was developed, said Tim Shellenberger, senior vice president of product engineering.
"American Water Heater (and its then-owner Southcorp Australia Pty Ltd.) had looked at various methods over a number of years but never quite got there," he noted. "With the advent of PCs, we used some pretty high-powered computer software to help develop the product."
While the combustion chamber is not 100% sealed (air is needed for combustion), it's sealed to the extent it needs to be to prevent any flammable vapors from flashing outside, he explained. The Flame Guard has a temperature sensor in the thermocouple that serves two purposes: 1) If there's a flammable vapor accident, and there are flames burning inside the combustion chamber, the sensor will shut down the gas flow to the burner and the pilot light; and 2) If the flame arrestor gets clogged, the sensor will also shut the system down safely.
The A.O. Smith Water Products Co. and State Industries will be introducing new C3 Technology gas water heaters. The C3 flame arrestor is made from fireproof Corderite, a ceramic material, said Mike Parker, vice president of marketing at A.O. Smith.
"Incoming air flows through the flame arrestor, which distributes the air evenly to the gas burner," he said. "If gas is accidentally spilled near the unit and the flammable vapors enter the combustion chamber, the flames burn off the top surface and can't escape through the flame arrestor."
C3 water heaters have a removable screen at the bottom of the unit for filtering out LDO while providing air for the combustion chamber. The units are also equipped with a thermal cut-off device to shut off gas flow during a flammable vapor ignition or excessive internal temperatures due to a clogged LDO screen.
A little different design comes from Rheem in the form of air intake on the sides of the water heater that prefilters the air entering the combustion chamber.
"Water heaters are often installed in locations such as laundry rooms, basements or garages, and most are designed to take their air from the base of the unit where a lot of lint and dust tend to accumulate," Bienias explained. "If the arrestor plate becomes blocked with contaminants, the unit may not combust properly. Once the water heater starts reburning the same air, it produces carbon monoxide."
Rheem's Guardian System takes air from the sides of the water heater. The airway to the combustion chamber has a baffle system, which causes the airflow to make several changes in direction. LDO is filtered out before the air enters the combustion and burner chambers.
Another significant difference is that the system completely shuts off the combustion chamber when a FVI occurs; this includes gas and air. The air shutoff system avoids overheating the unit in an uncontrolled burn.
Bradford White's version will have the same height as its conventional models, said Michael W. Gordon, vice president of engineering.
"That becomes an issue for installations where the piping is already set up; you just have to disconnect one and connect the other without having to redo piping," he said.
The company added a pedestal base to allow easier movement over floors for installation, as legs can catch on carpets or scratch up floors.
Bradford White's flame arrestor is made of stainless steel, which makes it very resistant to temperature in case of a flammable vapor incident. The FVIR water heater also has thousands of louvers that separate the combustion air coming in from where the burner is located. They are designed to do two things, Gordon explained: 1) Give velocity to the air coming in, and 2) Change its direction. The combination of the two prevents vapors in the air from flashing back.
The standard will not prompt any change-outs of installed products, said Bienias. In fact, he likened this new water heater standard to that of the 1.6-gpf toilets a few years ago.
And although the designs are different, these new water heaters aren't any more difficult to service than other water heaters. In fact, all four companies have equipped their new models with piezo electric igniters, the same kind used on gas grills, which makes the plumber's job a little easier.
"If you look at a Flame Guard product and a conventional water heater right next to each other, you probably wouldn't be able to tell the difference unless you knew what you were looking for," Shellenberger said.
The Bradford White unit is easy to clean and has a resetable thermal switch on the outside of the heater, which will make servicing the water heater easier. "We made a huge effort to make sure our FVIR water heater is seamless; it's arranged in such a way that it doesn't present any installation problems that might throw our installers off," Gordon said.
But new technology usually means product training. "Because the product is different, it could be interpreted as more difficult," Parker said. "It's new technology, and it may cause a little angst in the industry as people adapt to it. It's clearly an improvement and there's been a lot of work in the industry to try and develop this specific technology."
He said that A.O. Smith is planning to provide training for its servicers so that they understand what's different about the technology. Training would be done at its new training facility and in the field. The company is also working with a local university to develop a distance training capability.
Bradford White will roll out its training program about three months before the introduction date of the product, about the second quarter of 2003, Gordon said.
"The training is for our reps, our distributors and our contractors," he explained. "This will include educational material, tapes and presentations to get them comfortable with the technology."
Training will also be an issue for the folks at Rheem. "As products become a little more complex, contractors become a little bit more nervous," Bienias said. "In the spring of next year we will provide some training programs to all of our people, internally and externally, as well as some industry training to get contractors familiarized with the product and the changes."
One issue that will have an impact on the industry is price. "Water heaters have remained at a fairly reasonable price and unchanged for a number of years," he said. "With these new technologies, there could be a 50-60% cost increase, depending upon which level of the distribution chain you're in."
He added that Rheem anticipates a buildup of wholesaler inventories on older model water heaters in the weeks before the new standard takes effect. Rheem intends to limit orders to discourage such large inventory buildups.
American Water Heater has experienced the price problem since its introduction of Flame Guard. "The Flame Guard water heater represents a small portion of our sales," Shellenberger said. "And it's not necessarily because the consumer doesn't want to buy it, but some of our customers, our wholesalers, don't want to buy it because it costs more money."
Kelly Faloon is senior editor for Plumbing & Mechanical Magazine.