Boiler Manual
Figure 3 Sizing air openings for CGs installations
Room Air Openings
Required area of the air openings given in this table are free area — after the correction for louver obstruction. (See Exception below.)
Apply this table only to installations with clearances no smaller than those shown in Figure 1, page 7 of this manual.
For installations with clearances less than shown in Figure 1, page 7 of this manual, provide 2 openings, each with 1 square inch of free area per 1,000 Btuh of total input of all appliances.
Direct exhaust vent installation | Direct vent installation | |
(CGs using room air for combustion) | (combustion air piped to CGs) | |
| Combustion | Combustion |
| air piping | air piping |
Other | Other |
|
appliances | appliances |
|
CGs | CGs | CGs | CGs |
Room shared | CGs alone | Room shared | CGs alone |
with other appliances | in room | with other appliances | in room |
2 Openings — | 2 Openings — | 2 Openings — | NO Openings are |
each opening: | each opening: | each opening: | needed, provided: |
A Air from Inside | 12” | |
Max | ||
|
CGs
12”
Max
Air
opening
Inside | Outside |
Air
opening
1 square inch | 1 square inch | 1 square inch |
| |
free area per | free area per | free area per | Clearance around | |
1,000 Btuh input of | 4,000 Btuh input | 1,000 Btuh input of | boiler is NO LESS | |
than shown in | ||||
other appliances | of CGs | other appliances | ||
Figure 1, page 7 | ||||
plus CGs |
| only (not CGs) | ||
| of this manual. | |||
2 Openings — | 2 Openings — | 2 Openings — | NO Openings are |
BAir Directly from Outside
CGs |
12” |
Max |
Air |
opening |
Outside |
Air |
opening |
12” |
Max |
each opening: | each opening: | each opening: | needed, provided: | |
1 square inch | 1 square inch | 1 square inch |
| |
free area per | free area per | free area per | Clearance around | |
4,000 Btuh input of | 4,000 Btuh input | 4,000 Btuh input of | boiler is NO LESS | |
than shown in | ||||
other appliances | of CGs | other appliances | ||
Figure 1, page 7 | ||||
plus CGs |
| only (not CGs) | ||
| of this manual. | |||
2 Openings — | 2 Openings — | 2 Openings — | NO Openings are | |
each opening: | each opening: | each opening: | needed, provided: |
C Air from Outside | 12” |
|
|
| ||
|
| |||||
Max |
|
| ||||
Through horizontal | Air | |||||
ducts | ||||||
opening |
Duct |
|
Inside | Outside |
1 square inch | 1 square inch | 1 square inch |
|
free area per | free area per | free area per | Clearance around |
2,000 Btuh input of | 4,000 Btuh input | 2,000 Btuh input of | boiler is NO LESS |
CGs
Air
opening
12”
Max
Duct
other appliances | of CGs | other appliances | than shown in | |
Figure 1, page 7 | ||||
plus CGs |
| only (not CGs) | ||
| of this manual. |
Outside or ventilated attic
DAir from Outside or Attic — Lower Opening in Floor
or Vertical Duct |
| Duct | Outside |
CGs | 12” |
| |
|
| ||
|
|
| |
| Max | Or |
|
|
|
| |
Ventilated |
|
|
|
crawl space |
|
|
|
26007 |
|
|
|
2 Openings — | 2 Openings — | 2 Openings — | NO Openings are | |
each opening: | each opening: | each opening: | needed, provided: | |
1 square inch | 1 square inch | 1 square inch |
| |
free area per | free area per | free area per | Clearance around | |
4,000 Btuh input of | 4,000 Btuh input | 4,000 Btuh input of | boiler is NO LESS | |
than shown in | ||||
other appliances | of CGs | other appliances | ||
Figure 1, page 7 | ||||
plus CGs |
| only (not CGs) | ||
| of this manual. |
Exception to combustion air opening rules:
NO combustion air openings are needed when the boiler (and other appliances) are installed in a space with a volume NO LESS than 50 cubic feet per 1,000 Btuh of all installed appliances. Sum the total input of all appliances in MBH (1,000's of Btuh) and multiply this number times 50. Building must not be of Tight construction (see page 10).
Example: For total input of 100 MBH (100,000 Btuh), minimum volume is 50 x 100 = 5,000 cubic feet. At a ceiling height of 8 feet, space must have at least 5,000 ÷ 8 = 625 square feet (25 feet x 25 feet, for instance).
Part number | 11 |