Install Instructions

1 Determine unit location (continued)
15
3. Combustion Air from an Interior Space
You can direct combustion air to this unit using air from an
adjoining interior space. You must provide two openings from
the boiler room to the adjoining room. Each of the two openings
must have a net free area of one square inch per 1000 Btu input
(22cm² per kW), but not less than 100 square inches (645cm²).
Figure 1-8_Combustion air from an interior space
All dimensions are based on net free area in square inches.
Metal louvers or screens reduce the free area of a combustion air
opening a minimum of approximately 25%. Check with louver
manufacturers for exact net free area of louvers. Where two
openings are provided, one must be within 12'' (30 cm) of the
ceiling and one must be within 12'' (30 cm) of the floor of the
equipment room. Each opening must have a minimum net free
area as specified in TABLE 1B, page 12. Single openings shall be
installed within 12'' (30 cm) of the ceiling.
The combustion air supply must be
completely free of any flammable vapors
that may ignite or chemical fumes which
may be corrosive to the appliance. Common
corrosive chemical fumes which must be
avoided are fluorocarbons and other
halogenated compounds, most commonly
present as refrigerants or solvents, such as
Freon, trichlorethylene, perchlorethylene,
chlorine, etc. These chemicals, when
burned, form acids which quickly attack
the heat exchanger finned tubes, headers,
flue collectors, and the vent system. The
result is improper combustion and a non-
warrantable, premature unit failure.
CAUTION
⚠ WARNING
Any fan or equipment which exhausts
air from the boiler room may deplete the
combustion air supply and/or cause a
down draft in the venting system. Spillage
of flue products from the venting system
into an occupied living space can cause
a very hazardous condition that must be
corrected immediately. If a fan is used to
supply combustion air to the boiler room,
the installer must make sure that it does not
cause drafts which could lead to nuisance
operational problems with the boiler.
Exhaust Fans
Installation & Service Manual