SBD TANK TYPE HEATERS
SERVICE HANDBOOK
MAKE-UP AIR
VERTICAL DUCTS
1Square Inch Per 4,000 BTUH
Often it is more practical to install vertical make-up air ducts to the out doors. Again, two openings are required - one within 12 inches of the top of the enclosure and one within twelve inches of the bottom of the enclosure. Each opening shall have a free area of not less than 1 square inch per 4000 BTUH of the total input of all appliances within the enclosure.
MAKE-UP AIR
HORIZONTAL DUCTS
1 Square
Inch Per
2,000 BTUH
When the heater is installed in an interior room with no roof access for vertical ducts, horizontal make-up air ducts should be installed. When using horizontal ducts, two openings are required - one within 12 inches of the top of the enclosure and one within twelve inches of the bottom of the enclosure. Each opening shall have a free area of not less than 1 square inch per 2000 BTUH of the total input of all appliances within the enclosure.
Technical Training Department | 7 |
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