Johnson Controls LP8C/LPLC*MP Air Supply Openings and Ducts, Ventilated Combustion Air

368262-UIM-B-1008

Gable

Vent

	Ventilated
Optional	Attic
	Top Above
Inlet (a)
	Insulation
Soffit	Outlet
Vent	Air (a)
	Gas
	Water
	Heater
	Ventilated
	Crawl Space

Gas

VentGable

Vent

Ventilated

Attic

Top Above

Insulation

Soffit

Vent

Furnace	Gas
	Water
Inlet	Heater
Air (b)

Gas Vent

Furnace

Gas

Vent

Outlet

Air (b)

Inlet	Inlet	Heater	Furnace
		Gas
		Water
Air (a)	Air (b)

Outlet Air (a)

Inlet Air (a)

FIGURE 27: Outside and Ambient Combustion Air

Air Supply Openings and Ducts

1.An opening may be used in lieu of a duct to provide the outside air supply to an appliance unless otherwise permitted by the authority having jurisdiction. The opening shall be located within 12” (30.5 cm) horizontally from, the burner level of the appliance. Refer to “COMBUSTION AIR SOURCE FROM OUTDOORS and VENT AND SUPPLY AIR SAFETY CHECK” in these instructions for additional information and safety check procedure.

2.The duct shall be either metal, or a material meeting the class 1 requirements of CAN4-S110 Standard for Air Ducts.

3.The duct shall be least the same cross-sectional area as the free area of the air supply inlet opening to which it connects.

4.The duct shall terminate within 12 in (30.5 cm) above, and within 24 in (61 cm) horizontally from, the burner level of the appliance having the largest input.

5.A square or rectangular shaped duct shall only be used when the required free area of the supply opening is 9 in2 (58.06 cm2) or larger. When a square or rectangular duct is used, its small dimen- sionshall not be less than 3 in (7.6 cm).

6.An air inlet supply from outdoors shall be equipped with a means to prevent the direct entry of rain and wind. Such means shall not reduce the required free area of the air supply opening.

7.An air supply inlet opening from the outdoors shall be located not less than 12” (30.5 cm) above the outside grade level.

Combustion Air Source from Outdoors

1.Two permanent openings, one within 12 in (30.5 mm) of the top and one within 12 in (30.5 mm) of bottom of the confined space, Two permanent openings, shall communicate directly or by means of ducts with the outdoors, crawl spaces or attic spaces.

2.One permanent openings, commencing within 12 in (30.5 mm)of the top of the enclosure shall be permitted where the equipment has clearances of at least 1 in (2.54 cm) from the sides and back and 6 in (15.24 cm) from the front of the appliance. The opening shall communicate directly with the outdoors and shall have a min- imum free area of:

a.1 square in per 3000 Btu per hour (6.45 cm3 per 0.879 kW) of the total input rating of all equipment located in the enclosure.

b.Not less than the sum of all vent connectors in the confined space.

3.The duct shall be least the same cross-sectional area as the free area of the air supply inlet opening to which it connects.

4.The blocking effects of louvers, grilles and screens must be given consideration in calculating free area. If the free area of a specific louver or a grille is not known. Refer to Table 7 to estimate free area.

Ventilated Combustion Air

The ventilated attic space or a crawl space from which the combustion air is taken must comply with the requirements specified in “AIR SOURCE FROM OUTDOORS” in this instruction or in Section 5.3, Air for Combustion and Ventilation of the National Fuel Gas Code, ANSI Z223.1 (latest edition). This type installation requires two properly sized pipes. One brings combustion air from a properly ventilated attic space or crawl space and a second pipe that extends from the furnace vent connection (top right of unit) to the exterior of the building.

Vent and Supply (Outside) Air Safety Check Procedure

For Category I furnaces, vent installations shall be in accordance with Parts 7 and 11 of the National Fuel Gas Code, ANSI Z223.1/NFPA 54, and or Section 7 and Appendix B of the CSA B149.1, Natural Gas and Propane Installation Codes, the local building codes, furnace and vent manufacture's instructions.

Multi-story or common venting systems are permitted and must be installed in accordance with the National Fuel Gas Code, ANSI Z223.1/ NFPA 54 and / or the CSA B149.1, Natural Gas and Propane Installa- tion Codes, local codes, and the manufacture's instructions.

Vent connectors serving Category I furnaces shall not be connected into any portion of mechanical draft systems operating under positive pressure.

Horizontal portions of the venting system shall be supported to prevent sagging using hangers or perforated straps and must slope upwards not less than 1/4" per foot (0.635 cm/m) from the furnace to the vent ter- minal.

It is recommended that you follow the venting safety procedure below. This procedure is designed to detect an inadequate ventilation system that can cause the appliances in the area to operate improperly causing unsafe levels of Carbon Monoxide or an unsafe condition to occur.

Johnson Controls Unitary Products 21