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5
INSTALLATION
Do not install unit heaters in
corrosive or fl ammable atmospheres! Premature
failure of, or severe damage to the unit will
result!
Avoid locations where extreme
drafts can affect burner operation. Unit heaters
must not be installed in locations where air for
combustion would contain chlorinated, halo-
genated or acidic vapors. If located in such an
environment, premature failure of the unit will
occur!
Since the unit is equipped with an automatic gas ignition
system, the unit heater must be installed such that the
gas ignition control system is not directly exposed to
water spray, rain or dripping water.
NOTICE: Location of unit heaters is related directly to
the selection of sizes. Basic rules are as follows:
MOUNTING HEIGHT: Unit Heaters equipped with
standard fan guards must be installed at a minimum of
8 feet (2.4m) above the fl oor, measured to the bottom of
the unit. At heights above 8 feet (2.4m), less effi cient air
distribution will result. If a unit is to be mounted below
8 feet (2.4m) from the fl oor, an OSHA approved fan
guard is required on the unit.
AIRCRAFT HANGARS: Unit Heaters must be installed
in aircraft hangars as follows: In aircraft hangars, unit
heaters must be at least 10 feet (3.0m) above the upper
surface of wings or engine enclosures of the highest
aircraft to be stored in the hangar, and 8 feet (2.4m)
above the fl oor in shops, offi ces and other sections of
the hangar where aircraft are not stored or housed.
Refer to current ANSI/NFPA No. 409, Aircraft Hangars. In
Canada, installation is suitable in aircraft hangars when
acceptable to the enforcing authorities.
PUBLIC GARAGES: In repair garages, unit heaters must
be located at least 8 feet (2.4m) above the fl oor. Refer to
the latest edition of NFPA 88B, Repair Garages.
In parking structures, unit heaters must be installed so
that the burner fl ames are located a minimum of 18 in.
(457mm) above the fl oor or protected by a partition not
less than 18 in. (457mm) high. However, any unit heater
mounted in a parking structure less than 8 ft. (2.4m) above
the fl oor must be equipped with an OSHA approved fan
guard. Refer to the latest edition of NFPA 88A, Parking
structures.
In Canada, installation must be in accordance to the
latest edition of CGA B149 “Installation Codes for Gas
Burning Appliances and Equipment.”
AIR DISTRIBUTION: Direct air towards areas of
maximum heat loss. When multiple heaters are involved,
circulation of air around the perimeter is recommended
where heated air fl ows along exposed walls. Satisfactory
results can also be obtained where multiple heaters are
located toward the center of the area with heated air
directed toward the outside walls. Be careful to avoid all
obstacles and obstructions which could impede the warm
air distribution patterns.
Unit heaters should not be installed to maintain low
temperatures and/or freeze protection of buildings.
A minimum of 50°F (10°C) thermostat setting must
be maintained. If unit heaters are operated to maintain
lower than 50°F (10°C), hot flue gases are cooled
inside the heat exchanger to a point where water
vapor (a fl ue gas by-product) condenses onto the heat
exchanger walls. The result is a mildly corrosive acid that
prematurely corrodes the aluminized heat exchanger and
can actually drip water down from the unit heater onto
fl oor surface. Additional unit heaters should be installed
if a minimum 50°F (10°C) thermostat setting cannot be
maintained.
AIR FOR COMBUSTION: The unit heater shall be
installed in a location in which the facilities for
ventilation permit satisfactory combustion of gas,
proper venting, and the maintenance of ambient
air at safe limits under normal conditions of use.
The unit heater shall be located in such a manner as
not to interfere with proper circulation of air within the
confi ned space. When buildings are so tight that normal
infi ltration does not meet air requirements, outside air
shall be introduced per Sections 1.3.4.2 and 1.3.4.3 of
ANSI Z223.1 for combustion requirements. A permanent
opening or openings having a total free area of not less
than one square inch per 5,000 BTU/Hr (1.5 kW) of total
input rating of all appliances within the space shall be
provided.
NOTICE: Unit Heater sizing should be based on heat
loss calculations where the unit heater output equals
or exceeds heat loss.