When does a water heater become a boiler??

We are working on a 70,000 sq.ft. nursing home. There are two high temp, high capacity, gas fired "water heaters" that supply hot water for a commercial kitchen. I'm not sure yet if the domestic hot water is tempered off this supply or it may be completely separate.

The plumber had a boiler inspector on site last week and the inspector said that remote shutdowns will have to be provided for these "water heaters".....he called them boilers.

I have had to provide remote shutdowns for large boilers that provide building heat, but haven't had to do it for these smaller units. And of course in isn't engineered into this project so there were no rough-in's provided for the shutdowns.

When does a water heater become a boiler?? What is the difference?

thanks,
GJ

i'm not a plumber, but i seem to remember from years ago, aboard an oceanagraphic research vessel, (i was a ship's electrician, in another life), this difference was defined as "when the hot water heater becomes a "pressure vessel" with a test pressure certification as such, then its no longer a "heater", but is a "boiler". also, if memory serves me, it must be capable of maintaining a certain "saturation" temperature at a given "working" pressure.

hope this helps...my memory isnt as good as it was 30 years ago...

Such items are defined, and generally regulated, by the American Society of Mechanical Engineers' "Boiler & Pressure Vessel Code." I suppose that, technically, ALL water heaters would be considered "low pressure boilers."

I was told by the GC today that anything larger than 200,000 BTU capacity is considered a boiler by building code.

He also said that after this limit was put into code many manufacturers went back and changed the nameplate ratings on their equipment to 199,000 BTU to avoid this requirement.

GJ

[This message has been edited by golf junkie (edited 01-28-2003).]