Page 15 of 84
4.1.1 Service Clearances
Minimum service clearance for service is based on
cabinet size described in section 4.1.
4.1.2 Ventilation Clearances
In order to help ensure proper operation of an air-source
constructed unit, a 24" (61.0 cm) clearance for ventilation
must be maintained.
In addition, read and follow the additional ventilation
clearance guidelines below:
• Do not locate the unit under an overhang or near a
wall/other equipment that will short circuit hot air to
the coil intakes.
• Do not locate unit within 10’ (3.0 m) of exhaust fans
or flues.
• Do not locate the unit too close to another unit to
allow air recirculation.
4.2 Placement Considerations
The unit is typically mounted on a curb with ductwork
and utility connections usually going through the curb. It
may also be pad-mounted. (Contact factory for specific
instructions if unit is to be mounted in a different way [ie.
on mounting stand].)
Select a location where external water drainage cannot
collect around the unit. Locate the unit so roof runoff
water does not pour directly on the unit. Provide gutter or
other shielding at roof level. Where snowfall is anticipated,
mount the unit so all intakes and discharges are above
the maximum snow depth for the area. Unit shall not
be installed with inlet opening facing into the prevailing
wind direction in order to help prevent the possibility of
moisture entrainment.
When installed at ground level, the unit should be
mounted on a level concrete slab which should extend at
least 2" (5.1 cm) beyond the unit on all sides. The top of
the slab should be 2" (5.1 cm) above the ground level. The
depth of the slab below the ground level and its structural
design is governed by the type of soil and climatic
conditions. The slab must not be in contact with any part
of the building wall or foundation. The space between
the slab and the building wall prevents the possibility of
transmitting vibration to the building.
When installing a unit on the roof of a building, the
structural members supporting the unit must be sufficiently
strong for the weight of the unit and mounting rails.
4.3 Hardware
Unless otherwise specified, all hardware (except sheet
metal screws) must be torqued to settings from Table 1.
Table 1: Recommended Torque Settings
8.8
10.9
8.8
10.9
Bolt Head
Grade Marking
Nut
Grade Marking
Bolt Size:
Grade 2:
Grade 5:
10-24
27 in-Lb
42 in-Lb
1/4-20
65 in-Lb
101 in-Lb
5/16-18
11 ft-Lb
17 ft-Lb
3/8-16
19 fl-Lb
30 ft-Lb
8.8
10.9
8.8
10.9
Bolt Head
Grade Marking
Nut
Grade Marking
Bolt Size:
Grade 2:
Grade 5:
M5
6Nm
9Nm
M6
10Nm
15Nm
M8
25Nm
35Nm
M10
50Nm
75Nm
M12
85Nm
130Nm
M16
215Nm
315Nm
PR Series Installation, Operation, and Maintenance Manual
