Independence Installation, Operating, and Service Instructions

8
103538-08 - 3/18
Figure 3: Clearance to Combustible Materials
b. Known air inltration rate. Must be used where
air inltration rate is less than 0.40 air changes
per hour (ACH). Do not use an inltration rate
greater than 0.60 ACH.
Volume >
(21 ft
3
x Iother ) + (15 ft
3
x Ifan)
ACH
where: Iother = total input rate of all appliances other
than fan-assisted (Mbh)
Ifan = total input of fan-assisted appliances
(Mbh)
ACH = air changes per hour
Mbh = 1000 Btu per hour
c. Size and locate openings connecting indoor
spaces
i. Combining spaces on same story. Locate on
opening commencing within 12 in. of top of
enclosure. Locate second opening
commencing within 12 in. of bottom of
enclosure. Size each opening for minimum
free area of 1 in
2
per Mbh, but not less than
100 in
2
. Minimum dimension of air
openings not less than 3 in.
ii. Combining spaces in different stories.
Spaces on different stories are considered as
communicating when connected by one or
more openings in doors or oors having a
total minimum free area of 2 in
2
per Mbh.
3. Outdoor combustion air. Provide opening(s) to
outdoors per a or b below. Minimum dimension of
air openings not less than 3 in.
a. Two permanent openings method. Locate one
permanent opening commencing within 12 in. of
top of enclosure. Locate second permanent
opening commencing within 12 in. of bottom of
enclosure.
i. Direct communication or though vertical
ducts. Size each opening for minimum free
area of 1 in
2
per 4 Mbh of total input rating
of all appliances in enclosure.
ii. Through horizontal ducts. Size each
opening for minimum free area of 1 in
2
per 2
Mbh.
b. One permanent opening method. Locate one
permanent opening commencing within 12 in. of
top of enclosure.
I. Pre-Installation (continued)