Ventilation Air, Venting and Combustion Air Check

2.For fan-assisted appliances (such as this furnace), calcu- late using the following equation:

Required Volume fan ²	15 ft3	(	I fan	)
			1000 Btu / hr

	ACH

where:

Iother = all appliances other than fan-assistedinput in Btu per hour

Ifan = fan-assisted appliance input in Btu per hour ACH =air change per hour (percent of volume of space exchanged per hour, expressed as a decimal)

3.For purposes of this calculation, an infiltration rate greater than 0.60 ACH shall not be used in the equations above.

The following requirements apply to the Standard Method and to the Known Air Infiltration Rate Method.

SAdjoining rooms can be considered part of a space, if there are no closeable doors between rooms.

SCombining spaces on the same story. Each opening shall have a minimum free area of at least 1 in.2/1,000 BTUH (2,200 mm2/kW) of the total input rating of all appliances in the space

but not less than 100 in.2 (0.06 m2). One opening shall commence within 12 in. (304.8 mm) of the top, and one opening shall commence within 12 in. (304.8 mm) of the bottom, of the enclosure. The minimum dimension of air openings shall not be less than 3 in. (76.2 mm).

SCombining spaces in different stories. The volumes of spaces on different stories shall be considered as communicating spaces where such spaces are connected by one or more openings in

doors or floors having a total minimum free area of 2 in.2/1,000 BTUH (4,400 mm2/kW) of total input rating of all appliances.

SAn attic or crawl space may be considered a space that freely communicates with the outdoors provided there are adequate ventilation openings directly to outdoors. Openings MUST remain open and NOT have any means of being closed off. Ventilation openings to outdoors MUST be at least 1 square inch

of free area per 4,000 BTUH (550 mm2/kW) of total input rating for all gas appliances in the space.

SIn spaces that use the Indoor Combustion Air Method, infiltration should be adequate to provide air for combustion, ventilation and dilution of flue gases. However, in buildings with unusually tight construction, additional air MUST be provided

using the methods described in section titled Outdoor

Combustion Air Method:

SUnusually tight construction is defined as Construction with:

1.Walls and ceilings exposed to the outdoors have a continu- ous, sealed vapor barrier. Openings are gasketed or sealed and

2.Doors and openable windows are weather stripped and

3.Other openings are caulked or sealed. These include joints around window and door frames, between sole plates and floors, between wall-ceiling joints, between wall panels, at penetrations for plumbing, electrical and gas lines, etc.

Ventilation Air

Some provincial codes and local municipalities require ventilation or make-up air be brought into the conditioned space as replacement air. Whichever method is used, the mixed return air temperature across the heat exchanger MUST not fall below 60° so that flue gases will not condense excessively in the heat exchanger. Excessive condensation will shorten the life of the heat exchanger and possibly void your warranty.

Venting and Combustion Air Check

NOTE: If this installation replaces an existing furnace from a commonly vented system, the original venting system may no longer be sized to properly vent the attached appliances. An improperly sized venting system may cause the formation of condensate in the vent and the leakage or spillage of vent gases. To make sure there is adequate combustion air for all appliances,

MAKE THE FOLLOWING CHECK.

Vent	Pipe	Draft Hood
Typical Gas
Water Heater
		Match

A07688

Fig. 7 - Vent Check

The following information is supplied to allow the installer to make adjustments to the setup of existing appliances, IF REQUIRED, based on good trade practices, local codes, and good judgement of the installer. Manufacturer does NOT take responsibility for modifications made to existing equipment.

58HDV