Regulating Methods of Design and Installation of Warm Air Winter Air Conditioning Systems & Warm Air Heating Systems in Buildings

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(b) Registers for warm air, and warm air pipes, stacks and fittings shall not be located in outside walls unless properly insulated with 1 in. air cell covering or its equivalent on the cold side. (c) For any system having not more than two warm air openings, at least one of these openings shall be without valve or louvers and the pipe thereto shall be without, damper. (d) All applicable provision in the Underwriters' Standards shall be followed. (See Section 322). Section S - Return Air Supply to Furnace. (a) The selction of ducts, risers, fittings and intakes on the return air side shall be made in accordance with the standard method, outlined in the Manual, Sections C through G. Returns should be short, dieect, and with least number of turns and restrictions. (b) All applicable provisions in the Underwriters' Standards shall be followed. (See Section 360 entitled "Cold or Return Air Ducts. ") (c) The air supply to the furnace may be taken from within the building or may be taken partially from outside and partially from within. All joints in the duct system shall be made dust tight. (d) i7here a boot or shoe is connected to the casing at the base, the opening shall not extend higher than a line on the level of the top of the grate of the furnace. The width of the shoe shall be of proper measurement to make the area at all points at least equal to that of the round or square pipe. This boot or shoe shall be of streamline transition construction. (e) ITherever the space between joists is used to convey return air over head, all bridging and bracing shall be removed and a dust proof sheet metal bottom shall be constructed. If more area is required two or more spaces may be used, or a pan may be constructed to extend below the joist to obtain the required area. The connection from this pan to the boot or shoe shall be made of galvanized iron not lighter than No. 26 U. S. Standard Gauge, and shall have a transition fitting, the top area of which shall be at least 10 per cent greater than the area of the connecting pipe. To reduce friction and for the sake of cleanliness, it is recommended that the joists and all wooden surface between such joists be lined with metal.