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B. Locating the Unit
Prior to locating the unit, authorities having jurisdic-
tion should be consulted before installations are made.
Approval permits should be checked against the unit
received.
On Direct Gas-Fired units, which recirculate room air,
outside ventilation air must be provided in accordance
with the information shown on the heater nameplate.
All ventilation air to the heater must be ducted directly
from the outside. See Section XIII.
If in doubt regarding the application of this appliance,
consult the factory.
Locate the unit exactly level. Special attention should
be given to the duct, electrical, and fuel connection
points. Install duct work with adequate fl exible connec-
tions to isolate vibration from the duct work. All duct
work should have taped or caulked seams. Duct work
should be properly sized so as not to inhibit airfl ow.
This information should be cross-checked with the
position of support beams and stand pipes to insure
that clearance dimensions coincide with those of the
unit. The minimum clearance to combustible material
must be maintained as listed in Table 1.
Table 1
Minimum clearance to combustible material,
also consult local codes and regulations.
Clearances to Combustible Material
Vertical
Units Horizontal Units
Front*
39 inches
39 inches
Rear
6 inches
6 inches
Right
6 inches
6 inches
Left
6 inches
6 inches
Top
12 inches
12 inches
Floor
Zero
6 inches
*Consider control side as front of unit.
**Optimum clearance for shaft removal would be
equivalent to cabinet width.
Make a visual inspection to insure no damage has oc-
cured to the unit during installation.
C. Curb Mounted Units
Outdoor units can be supplied with an optional roof
curb. The curb greatly facilitates installation thereby
reducing installation costs. All connections to the unit:
duct, piping, electrical power and control wiring can
be made through the roof opening. The curb may be
shipped prior to unit shipment. All curbs are shipped
un-assembled from the factory.
Use extreme caution in handling the curb. Proper han-
dling and positioning will assure a water-tight curb unit
installation.
Re-check approval prints prior to installation. Be sure
that there are no obstructions to ducting and that
proper planning has been exercised in connection of
piping and/or electrical services.
The curb assembly may be bolted or welded to either
trusses or roof decking; however, connection to roof
trusses is recommended. The curb is designed to carry
the weight of the unit. Additional support is required for
certain applications.
Placement of the curb is critical in squareness and
leveling. Shims for leveling must be applied to the
curb; application of shims to the unit will tend to
destroy the sealing effect after installation. Make sure
sealing tape is in place before unit is set. Be careful
not to allow gaps where two pieces of sealing tape
meet. A bubble level must be used in the leveling
process. Measure across diagonals to check for
squareness. Allowable tolerance is 1/4" difference
between diagonal measurements. Double-check
approval prints before setting the unit.
Upon completion of setting the curb, apply roofi ng
material and fl ashing as required.
D. Location of Accessories
Where applicable, standard or optional accessories will
be placed inside the fan section of the unit for shipment,
and must be removed and installed by the mechanical
or electrical contractor. The inlet hood(s) must be
mounted with a fi eld supplied support. Remotely located
discharge or inlet dampers must be equipped with an
end switch and interlocked to insure maximum design
opening before starting and running circuits may be
energized.
Field constructed intake accessories should be properly
designed to minimize the entry of rain and snow.
Adequate building relief must be provided, so as to not
over-pressurize the building, when the heater is
operating at its rated capacity. This can be accom-
plished by taking into account, through standard
engineering methods, the structure’s designed infi ltra-
tion rate, by providing properly sized relief openings,
by interlocking a powered exhaust system, or by a
combination of these methods.
