Chapter 4, Ventilation Air Supply, is hereby amended by adding the following section:

408.0 Return Air Location. Return air shall be obtained from an approved interior location of the same building. Return air shall not be obtained from the following locations:

1. Where it will pick up objectionable odors, fumes or flammable vapors.

2. A hazardous location.

3. An unsanitary location.

4. An area having a volume less than 25 percent of the entire volume served by the supply air system, unless there is a sufficient permanent communicating opening to areas having a volume equal to the required 25 percent. Appropriately sized transfer grills or door undercuts may be used to provide the required opening.

Exception: Such opening when used for a warm-air furnace in a dwelling unit may be reduced to no less than 50 percent of the required area, provided the balance of the required return air is taken from a room or hall having at least three doors leading to other rooms served by the furnace.

5. A refrigeration machinery room.

6. A room or space containing fuel-burning equipment.

Exceptions:

1. Fireplaces, fireplace appliances, residential cooking appliances, direct-vent appliances, enclosed furnaces and domestic-type clothes dryers.

2. A listed vented wall furnace.

3. A blower-type system where:

a. The return air is taken from a room or space having a volume exceeding 1 cubic foot for each (10 Btu/h);

b. At least 75 percent of the supply air is discharged back into the same room or space; and

c. The return-air inlet shall not be located within ten (10) feet (3048 mm) of any appliance firebox or draft diverter in the same enclosed room or confined space.

7. A closet, bathroom, toilet room or dwelling unit kitchen.

8. Corridors shall not be used to convey air to or from rooms if the corridor is required to be of fire-restrictive construction by the current Building Code.

9. Return air from one dwelling unit shall not be discharged into another dwelling unit through the heating/cooling system.