McQuay IM 987
15
Mechanical Installation
Figure 15: Service Clearances, Unit with SWSI Plenum Supply Fan
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
Figure 15
.
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 16
). This is particularly
important to prevent blowing snow from entering the 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 following restrictions must be observed for overhead
obstructions above the air handler section (see
Figure 16
):
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.
Roof
walkway
To roof
access
location
Varies with unit arrangement.
Refer to Certified Drawing and
note below.
96"
(2438 mm)
60"
(1524 mm)
72"
(1829 mm)
72"
(1829 mm)
A
B
C
D
Legend:
A = Return air section
B = Filter section
C = Cooling section
D = Cooling/supply fan section
E = Heat section
F = Discharge plenum section
Dimension "X"
RDS 800–802 = 90" (2286mm)
RAH 47–77 = 96" (2438mm)
Note:
Sections with heating and/or cooling coils or DWDI
supply fan must have noted service clearance on the
control box side.
X
E
F
