Outside Air Recommendation; Minimum Area In Square Feet For Unconfined Space Installation; Minimum Free Area In Square Inches Each Opening; Confined Space Air From Inside Building - Trane AUH1B040A9241A Installer's Manual

Installer's Guide
OUTSIDE AIR IS RECOMMENDED
The use of indoor air for most applications is acceptable,
unless there is the presence of corrosive chemicals or
contamination. Certain types of installation will require
the use of outside air for combustion.
The following types of installations will require use of
OUTDOOR AIR for combustion, due to chemical exposures:
* Commercial buildings
* Buildings with indoor pools
* Furnaces installed in "confined" laundry rooms
* Furnaces installed in "confined" hobby or craft rooms
* Furnaces installed near chemical storage areas.
Exposure to the following substances in the combustion air
supply will also require OUTDOOR AIR for combustion:
* Permanent wave solutions
* Chlorinated waxes and cleaners
* Chlorine based swimming pool chemicals
* Water softening chemicals
* Deicing salts or chemicals
* Carbon Tetrachloride
* Halogen type refrigerants
* Cleaning solvents (such as perchloroethylene)
* Printing inks, paint removers, varnish, etc.
* Hydrochloric acid
* Cements and glues
* Antistatic fabric softeners for clothes dryers
* Masonry acid washing materials
Furnace locations may be in a "confined space" or an "un-
confined space".
Unconfined space is defined in Figure 6. These spaces may
have adequate air by infiltration to provide air for combus-
tion and ventilation. Buildings with tight construction (for
example, weather stripping, heavily insulated, caulked, va-
por barrier, etc.), may need additional air to be provided as
described for confined space.
Confined spaces are installations with less than 50 cu. ft. of
space per 1000 BTU/hr input from all equipment installed,
as in Figure 7. Air for combustion and ventilation require-
ments can be supplied from inside the building as in Figure
8 or from the outdoors, as in Figure 9.
Table 2
MINIMUM AREA IN SQUARE FEET
FOR UNCONFINED SPACE INSTALLATIONS
FURNACE MAXI- WITH 8 FT. CEILING
MUM BTUH INPUT MINIMUM AREA IN SQUARE FEET
RATING OF UNCONFINED SPACE
40,000
60,000
80,000
97,000
110,000
7
CONFINED
SPACE
8
250
375
500
625
688
1. All air from inside the building as in Figure 8: The con-
fined space shall be provided with two permanent open-
ings communicating directly with an additional room(s)
of sufficient volume so that the combined volume of all
spaces meets the criteria for an unconfined space. The
total input of all gas utilization equipment installed in
the combined space shall be considered in making this
determination. Refer to Table 2 for minimum open ar-
eas requirements.
2. All air from outdoors as in Figure 9: The confined space
shall be provided with two permanent openings, one
commencing within 12 inches of the top and one com-
mencing within 12 inches of the bottom of the enclo-
sure. The openings shall communicate directly, or by
ducts, with the outdoors or spaces (crawl or attic) that
freely communicate with the outdoors. Refer to Table 2,
for minimum open areas requirements.
TABLE 3
MINIMUM FREE AREA IN SQUARE INCHES
EACH OPENING (FURNACE ONLY)
Furnace
Air
Maximum
From
BTUH/INPUT
Inside
Rating
40,000 100
60,000 100
80,000 100
97,000 100
110,000 110
8
Air From Outside
Vertical Horizontal
Duct Duct
10 20
15 30
20 40
25 50
28 55
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