Feature
by Bright Winn
How dangerous is a water heater? It can be very dangerous if it is not installed according to code. When examining your water heater make sure it is on a stand if it is in a garage. Check if the water heater is seismically braced. Does it have a TP/Valve? Does the TP/Valve have a blow-off tube extending to a drain or outside to the ground? Is there adequate combustion air? Let’s look at these problems individually.
Fire Hazard
In the U.S. there are about 1,000 fires a year that are caused by water heaters in a garage. If a water heater in a garage is not placed on a stand, then the pilot light can ignite gasoline fumes from cars, paint thinner, charcoal lighter fluid and most solvents. If a water heater is not seismically braced to code, then it can fall during an earthquake. Should this happen, the gas connection can break and an explosion could soon follow.
All water heaters up to 50-gallons and manufactured after July 1, 2004 are now flammable vapor-ignition resistant. What this means is that all the combustion chambers on the new units have a filtering system that will allow combustible fumes into the chamber but will not allow flames back out of the chamber. It is a very clever invention. When the temperature in the chamber is raised above that of combusting natural gas, the whole unit shuts down. By combining this new technology with the code requiring the placement of water heaters on a stand, the chance of a fire has now been reduced dramatically.
Water heaters must be seismically braced. This means that there must be two straps, high and low, around the unit and attached to the building. The screws must be 1⁄4" x 3" in order to attach the strapping, also known as plumber’s tape. Anything less is not according to code. The strapping must be tear-dropped, which means it must circle the heater twice and then attach at opposite ends. There are kits out there that have all the right parts. Also, make sure to check the water-heater stand, which is supposed to be bolted to the building or the floor.
Scalding
If a water heater does not have a blow-off tube attached to the TP/Valve (temperature/pressure relief valve), then 210-degree water could spray out and harm a person in the area.
All water heaters are now supplied with a TP/Valve. As its name describes, this is a safety device that opens when either the temperature or pressure in the unit exceeds the levels at which the valve is set. Most valves are rated to open at 210 degrees and 150 pounds pressure. When this device opens, water shoots out. The user is protected from scalding if a blow-off tube has been installed. The tube is a pipe that is supposed to run either to a drain or to the exterior of the building and terminate 24" above the ground.
Explosions
If a TP/Valve is not installed on a water heater and there is a failure of the energy cut-off valve (ECO/Valve), the pressure within the tank will go beyond 150 pounds, and the unit will literally become a rocket and shoot through the roof.
Again, we look to the temperature/pressure relief valve to protect the user. The pressure inside a water heater can exceed 150 pounds if the unit continues to run and the ECO/Valve fails. This valve is behind the gas controls and is simply a thermometer in the tank that will turn the gas off if the temperature exceeds 170 degrees. But if the ECO/Valve fails, then the T/P Valve will open and release the pressure within the unit—no explosion.
Asphyxiation
If a water heater is not vented correctly nor supplied with adequate combustion air, then it can and will create carbon monoxide, which is a deadly poison. People in the area can die. Most water heaters must be vented to the roof. There are some vents—power vents and direct vents—that do not require a vent to the roof. But the vast majority must be vented. The vent must be graded upward at no less than 1⁄4" per foot. The vertical distance must exceed the horizontal run by two-thirds. The vent pipe that penetrates the wall and the exterior of the building must be double-wall (type B) vent pipe. If the products of combustion cannot flow out of the water heater, they will stack up and the water heater will begin to create carbon monoxide.
In addition to a code flue, there must be adequate combustion air within the area. This means that for every 1,000 BTUs (British Thermal Units) the water heater burns in one hour, there must be 50 cubic feet of space in that same area. Without adequate combustion air, the unit will again create carbon monoxide.
Areas not Conducive to the Installation of Water Heaters
Vent-type water heaters may never be installed in a bedroom or in a bathroom that contains a bathtub. This also means they may not be installed in a closet or room directly off of a bedroom or bathroom with a bathtub. Water heaters use oxygen to burn, so if there is not adequate air in a bedroom, the sleeper and the water heater are competing for the limited oxygen. Why the bathtub? The answer is that some folks fall asleep in a bathtub.
There are many kinds of water heaters manufactured with several safety systems, but if they are improperly installed they can be dangerous. Always hire a licensed plumbing contractor to install your water heaters.
The opinions expressed in this article are those of the author and do not necessarily reflect the viewpoint of SFAA or the San Francisco Apartment Magazine. Bright Winn is owner of Bright Plumbing NJ Cohen Inc. in San Francisco and has been prominent in the Bay Area plumbing industry for 35 years. He can be reached at 415-671-1500, brightplumbing@aol.com. Copyright © 2005 by the San Francisco Apartment Magazine. All rights reserved.