Emergency Air Handler Shutoff

[Skip Erwin]

I came across this today. Sorry for the bad picture. Obviously its purpose is to shut off the air handler in an emergency. It's in a Townhome that's a business on the first level and residential on levels two and three. All three levels are serviced by one HVAC system. Is it so that the fire department doesn't have to look for the thermostat? What are the primary concerns? Is it an issue with gases on the first floor being spread to the upper levels? Or could they be worried about gases inside somehow being exhausted outside?

[Greg Veal]

Skip

For the most part the design (as bad as it is, in MY opinion) is to shut down the airflow to minimize fanning the flames, in case of fire, on any floor.
I assume there is some sort of automatic volume damper (VAV), incorporated with a fire rated damper (FD-type B?) for each floor/zone. It's dumb, especially in a Comm./Res. mixed use setting.

[bbenjamin]

In some states this is a DHEC regulation for such applications as Day Cares and Nursing Homes. They should be used in accordance and along with duct smoke detectors which if use correctly will prevent the spread of smoke through the duct system. Sprinklers are also a part of this regulation.