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Dom D'Agostino · #5 (**permalink**) 05-28-2008, 10:04 PM

Quote:

Originally Posted by Jon Randolph

If it is a sealed burner, it is not required to be 18" off of the floor.

BTW...

Where does a sealed burner unit get it's combustion air from? Seems to me that the combustion air would have to come from around the burner area, which would negate the allowance to be on the floor.

From State Water Heaters Technical Reference:

On July 1, 2003, all residential gas water heater manufacturers introduced 30, 40 and 50-gallon atmospheric models with "Flammable Vapor Ignition Resistant" design. Every manufacturer's design must meet standards and protocols established by the American National Standards Institute (ANS Z21.10.1). And, while all manufacturers' designs are unique in some respects, all incorporate the following features:

A Flame Arrestor, located beneath the burner, designed to permit combustion air to flow up through it to sustain combustion, but to prevent flames from escaping downward through it in the event of flammable vapor ignition.
A Thermal Cutoff switch (TCO), designed to shut the unit down when it senses excessive temperatures caused by inadequate combustion air inside the combustion chamber

Dom.