Ventilation Louvres

A.O.Smith gas water heater combustion and ventilation air flow?

I live in central Tx. I just installed a A.O. Smith natural gas water heater and when inspected it failed because they said the water heater had to elevated above the pan because the air intake is the lowest part of the water heater, and was blocking the combustion. I just wanted to know if this was part of the manufacturers installation deal or part of the IRC 06, because I could not find it ANYWHERE? THANKS for info. P.s. water heater was installed in attic, and I looked at other new residential houses and they were using the same type of bottom air intake water heater and they were raised by bricks.

Public Comments

1. It's in the IBC and the plumbing code, you need to have combustion air supplied to the water heater, the reason for raising it is for the combustible gas that may cause an explosion if it is set directly on the floor. It requires 2 permanent openings in a confined area one 12" from the top and one 12" from the bottom.They must provide enough air for combustion , ventilation and dilution of flue gases. That can be found in chapter 23 of the Plumbers Handbook under Hot Water Systems.
2. I'm a plumber, but one without the current code book, so I can't tell you if it's a requirement. But this you need to know. For a lot of people, AO Smith, and other State Industries water heaters, such as Sears and Reliance are a problem child because of the mandated 2003 flamegard design. That being the case, you need easy access to the bottom of the heater to clean the flame retention screen. Because of the future problems you'll have, it's best to raise the heater. Now, if the pan has a drain and is larger by several inches in diameter than the water heater, I see no functional reason to raise the heater. As long as it can draw it's air. Anyway, I'm buying a 2009 UPC code book shortly. I'll put you on my watch-list, and when I get the blasted $100 book in, I'll let you know what it says. Until now, I haven't heard of IRC. Most areas are under IPC, UPC, Boca and others.