This is an HVAC air handler with a split condensing unit. The fire alarm turns of the heater and/or the supply air blower. There are two exhaust fans blowing out horizontally on the left and right sides of the return air stack.
The whole unit can be disabled by a remote signal and of course disconnecting main power. It is currently set up to stop the supply blower and vent smoke with the exhaust fans until the unit is disabled. The customer has not responded yet on what they require and if their fire system can disable the unit if the fire is directly in the zone the air handler supplies.
