Table of Contents
Advertisement
INSTALLATION
Combus on Air Supply Op ons
Gable vent
to outdoors
Install above
Outlet air to
per 4,000 btu/h
Alternate
Air Inlet
2
2
)
per 4,000 btu/h
Figure 9 - Direct to Outdoors Openings
12" (305 mm)
maximum
Two permanent
Openings
1 in
2
(6.5 cm
2
)
Space
per 4,000 btu/h
12" (305 mm)
maximum
Figure 10 - Direct to outdoors openings. Two
permanent openings.
Table 6:
Minimum Free Area of Permanent Openings for Ven la on and Combus on Air Supply – Air from outdoor or indoor spaces.
Based on the total BTU/hr input ra ng for all gas burning appliances within a confi ned space.
Opening Source
Direct to outdoors*
Ver cal ducts
Horizontal ducts
Single Opening
Two permanent openings
to another room**
*These openings connect directly with the outdoors through a ven lated a c, a ven lated crawl space, or through an outside wall.
**United States: For direc on on combining spaces in diff erent stories within the structure, refer to the current edi on of the Na onal Fuel Gas Code ANSI
Z223.1/NFPA 54. In Canada, refer to the current edi on of B149.1 Natural gas and propane installa on code.
20 • Residen al Gas Tankless Water Heater Use and Care Guide
2
2
)
Figure 11 - Ver cal Duct Openings
Space
Figure 12 - Horizontal Duct Openings
Minimum Free Area
2
2
1 in
(6.5 cm
) per 4,000 BTU/hr (See Figure 9 & Figure 10)
1 in
2
(6.5 cm
2
) per 4,000 BTU/hr (see Figure 11)
1 in
2
(6.5 cm
2
) per 2,000 BTU/hr (see Figure 12)
1 in
2
(6.5 cm
2
) per 3,000 BTU/hr (see Figure 13)
2
2
1 in
(6.5 cm
) per 1,000 Btu/hr (see Figure 14)
Opening: 100 in
2
(645 cm
Minimum dimension of air openings: no less than 3 in (76 mm)
Outlet air to
2
2
)
per 4,000 btu/h
2
2
)
per 4,000 btu/h
1 in
2
(6.5 cm
2
)
per 2,000 btu/h
Outlet
Air Ducts
Inlet
2
2
1 in
(6.5 cm
)
per 2,000 btu/h
2
) Min
1 in
Figure 13 - Single Opening
12" (305 mm)
maximum
Space
1 in
Two permanent
1,000 btu/h
Openings
12" (305 mm)
maximum
Figure 14 - Two permanent openings
2
(6.5 cm
2
)
btu/h
2
per
Advertisement
Table of Contents
