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I-EEDU (02-21) 150492-A
Table 15. Minimum Clearance Requirements for Horizontal Vent Terminal
Component/Structure
Minimum Clearance, All Directions Unless Specified (Feet (Meters))
Forced air inlet within 10 feet (3 .1 meters)
*
3 (0 .9) above
Combustion air inlet of another appliance
6 (1 .8)
Mechanical air supply inlet to any building
Canada: 6 (1 .8)
Any building opening (door, window, or gravity air inlet)
4 (1 .2) horizontal and below
1 (0 .3) above
Gas meter,
**
electric meter, and relief equipment
US: 4 (1 .2) horizontal
Canada: 6 (1 .8) horizontal
Gas regulator
**
US: 3 (0 .9) horizontal
Canada: 6 (1 .8) horizontal
Adjoining building or parapet
6 (1 .8)
Adjacent public walkway
7 (2 .1) above
Grade (ground level)
3 (0 .9) above
*
Does not apply to the inlet of a direct vent appliance .
**
Do not terminate the vent directly above a gas meter or service regulator .
Duct Connections
⚠ CAUTION ⚠
Joints where ducts attach to furnace must be sealed securely to prevent air leakage into burner
rack area. Leakage can cause poor combustion, poor performance, and pilot problems and can
shorten heat exchanger life.
NOTE: If the furnace is equipped with a unit-mounted ductstat (option AG3), the sensing bulb must
be removed from the mounting bracket (save the retainer clip) before the ductwork can be attached
(refer to
Option AG3: Discharge Air Temperature Sensor Installation
Ductwork Requirements
• Type:
the type of duct installation to be used depends in part on the construction type of the roof (wood joist, steel
bar joist, steel truss, or pre-cast concrete) and ceiling (hung, flush, etc .) .
• Material:
rectangular duct should be constructed of not lighter than #26 US gauge galvanized iron or #24 B&S
gauge aluminum .
• Size:
proper sizing of supply air ductwork is necessary to ensure a satisfactory heating installation . The recognized
authority for such information is the Air Conditioning Contractors Association, 2800 Shirlington Road, Suite 300,
) . A manual covering duct sizing in detail may be purchased directly from them .
• Structure:
all duct sections 24 inches (610 mm) or wider and over 48 inches (1,219 mm) in length should be
cross-broken on top and bottom and should have standing seams or angle-iron braces .
• Joints:
should be S and drive strip or locked .
• Ductwork through masonry walls:
no warm air duct should come in contact with masonry walls . Insulate around
all air ducts through masonry walls with not less than 1/2 inch (1 inch is recommended) of insulation .
• Ductwork through unheated space:
insulate all exposed warm air ducts passing through an unheated space
with at least 1/2 inch (1 inch is recommended) of insulation .
• Supports:
suspend all ducts securely from buildings members . Do not support ducts from unit duct connections .
• Removable panels:
ducts should have removable access panels on both upstream and downstream sides of the
furnace . These openings must be accessible when the furnace is in service and should be a minimum of 6
×
10
inches in size so smoke or reflected light may be observed inside the casing to indicate the presence of leaks in
the heat exchanger . The covers for the openings must be attached in such a manner as to prevent leakage (refer
to
Ductwork-to-Furnace Connections
section) .
