22
IM 738-2
Mechanical Installation:
Ventilation Clearance
Ventilation Clearance
Below are minimum ventilation clearance recommendations.
The system designer must consider each application and
provide adequate ventilation. If this is not done, the unit will
not perform properly.
Unit(s) surrounded by a screen or a fence:
1
The bottom of the screen or fence should be at least 1 ft.
(305 mm) above the roof surface.
2
The distance between the unit and a screen or fence should
be as described in “Service Clearance” on page 21. See also
Figure 26 on page 21.
3
The distance between any two units within a screen or
fence should be at least 120" (3048 mm).
Unit(s) surrounded by solid walls:
1
If there are walls on one or two adjacent sides of the unit,
the walls may be any height. If there are walls on more than
two adjacent sides of the unit, the walls should not be
higher than the unit.
2
The distance between the unit and the wall should be at
least 96" (2438 mm) on all sides of the unit.
3
The distance between any two units within the walls should
be at least 120" (3048 mm).
Do not locate outside air intakes near exhaust vents or other
sources of contaminated air.
If the unit is installed where windy conditions are common,
install wind screens around the unit, maintaining the
clearances specified (see Figure 27). This is particularly
important to prevent blowing snow from entering outside air
intake and to maintain adequate head pressure control when
mechanical cooling is required at low outdoor air
temperatures.
Overhead Clearance
1
Unit(s) surrounded by screens or solid walls must have no
overhead obstructions over any part of the unit.
2
The area above the condenser must be unobstructed in all
installations to allow vertical air discharge.
3
The following restrictions must be observed for overhead
obstructions above the air handler section (see Figure 27):
a
There must be no overhead obstructions above the
furnace flue, or within 9" (229 mm) of the flue box.
b
Overhead obstructions must be no less than 96"
(2438 mm) above the top of the unit.
c
There must be no overhead obstructions in the areas
above the outside air and exhaust dampers that are
farther than 24" (610 mm) from the side of the unit.
Figure 27. Overhead clearance
24" (610 mm)
maximum
96" (2438 mm)
minimum,
top of unit to
permanent
overhead
obstruction
24" (610 mm)
maximum
Overhead
canopy
9" (229 mm)
minimum to flue box,
typical all sides
Flue box
Summary of Contents for RDT- 036c
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