Make-up air direct communication, Make-up air vertical ducts – A.O. Smith 960 through 967 User Manual
Page 11
Attention! The text in this document has been recognized automatically. To view the original document, you can use the "Original mode".
BTH S E R V I C E H A N D B O O K
I N S T A L L A T I O N
MAKE-UP AIR
Direct Communication
Each opening shall
have a free area not
less than:
1 square inch per
4000 BTUH total input
all appliances within
the enclosure
Inlake
Air
12
”
Opening
Iniciko
Air Opening
L
12
”
A fresh supply of make-up air for combustion can be supplied to the heater through make-up air
openings, which directly communicate with the out of doors. Two openings are required — one
within 12 inches of the top of the enclosure and one within 12 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.
The lower opening is primarily providing combustion air. The upper opening is providing vent dilu
tion air and acts as a relief opening for flue gases should the vent become obstructed or a down
draft condition occur.
MAKE-UP AIR
Vertical Ducts
Air Intake Ducts
Each opening shall
have a free area not
less than:
12”
1 square inch per
4000 BTUH total input
all appliances within
the enclosure
12”
Often it is more practical to install vertical make-up air ducts to the outdoors. Again, two openings
are required — within 12 inches (30 cm) of the top of the enclosure and one within 12 inches (30
cm) 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.
Technical Training Department
TC-044 Revision 6
10
A. O. Smith Water Products Co.
Ashland City, Tennessee © 2004