International comfort products H8UH5050B12C2 Installation Instructions Manual page 8

Requirements
1. Provide the space with sufficient air for proper combustion and
ventilation of flue gases using horizontal or vertical ducts or
openings.
2. Figure 6 illustrates how to provide combustion and ventilation
air when two permanent openings, one inlet and one outlet, are
used.
a. One opening MUST commence within 12" (305 mm) of the
floor and the second opening MUST commence within 12"
(305 mm) of the ceiling.
b. Size openings and ducts per Table 1.
c. Horizontal duct openings require 1 square inch of free area
per 2,000 BTUH (1,100 mm
gas appliances in the space (see Table 1).
d. Vertical duct openings or openings directly communicating
with the outdoors require 1 square inch of free area per 4,000
2
BTUH (550 mm /kW) for combined input of all gas appliances
in the space (see Table 1).
3. When one permanent outdoor opening is used, the opening
requires:
a. 1 sq. in of free area per 3,000 BTUH (700 mm
combined input of all gas appliances in the space (see
Table 1) and
Figure 6
Outside Air (This is ONLY a guide. Subject to codes of country having jurisdiction.)
This installation NOT approved in Canada
Gable Vent
Gas Vent
Ventilated Attic
Top Above Insulation
Outlet Air (1)
Inlet
Air (1)
Furnace
Ventilated Crawl Space
Minimum One Inlet and One Outlet Air Supply is Required
May be in and Combination Shown
Inlet Air Opening Must be Within12"(305mm) of floor
Outlet Air Opening Must be Within12"(305mm) of ceiling
2
(1) 1 Square Inch (6cm ) per 4000 BTUH
2
(2) 1 Square Inch (6cm ) per 2000 BTUH
Free Area
Table 1
BTUH
Input
Two Horizontal Ducts
Rating
(sq. in./2,000 BTUH)
50,000
75,000
100,000
125,000
140,000
EXAMPLE: Determining Free Area
Furnace Water Heater
100,000 +
Furnace Water Heater
100,000 +
8
2
/kW) of combined input for all
Gas Vent
Optional Inlet Air (1)
Soffit Vent
Inlet
Furnace
Air (1)
Minimum Free Area Required for Each Opening or Duct to Outdoors
25 sq. in.
37.5 sq. in.
50 sq. in.
62.5 sq. in.
70 sq. in.
Total Input
30,000 = (130,000 ÷ 4,000)
Total Input
30,000 = (130,000 ÷ 2,000)
Specifications are subject to change without notice
b.
not less than the sum of the areas of all vent connectors in the
space.
The opening shall commence within 12" (305 mm) of the top of the
enclosure. Appliances shall have clearances of at least 1" (25.4
mm) from the sides and back and 6" (152 mm) from the front. The
opening shall directly communicate with the outdoors or shall
communicate through a vertical or horizontal duct to the outdoors or
spaces (crawl or attic) that freely communicate with the outdoors.
4. Combination of Indoor and Outdoor Air shall have:
a. Indoor openings that comply with the Indoor Combustion
Air Method below and
b. Outdoor openings located as required in the Outdoor
Combustion Air Method above and
c. Outdoor openings sized as follows.
1) Calculate the Ratio of all Indoor Space volume divided by
required volume for Indoor Combustion Air Method.
Outdoor openings sized as follows.
2) Outdoor opening size reduction Factor is 1 minus the
Ratio in 1) above.
2
/kW) for 3) Minimum size of Outdoor openings shall be the size
required in Outdoor Combustion Air Method above
multiplied by reduction Factor.
Gable Vent
Ventilated Attic
Top Above Insulation
Soffit Vent
Outlet Air (1)
Inlet
Air (2)
Single Opening
(sq. in./3,000 BTUH)
16.7 sq. in.
25 sq. in.
33.3 sq. in.
41.7 sq. in.
46.7 sq. in.
= 32.5 Sq. In. Vertical
= 65 Sq. In. Horizontal
Gas Vent
Outlet
Air (1)
Furnace
Inlet
Air (1)
Two Vertical Ducts or
Openings
(sq. in./4,000 BTUH)
12.5 sq. in.
18.75 sq. in.
25 sq. in.
31.25 sq. in.
35 sq. in.
Outlet
Air (2)
Inlet
Air (2)
Rd Duct
(sq. in. /4,000 BTUH)
4"
5"
6"
7"
7"
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