M-Series Technical Manual
9
Cambridge Engineering, Inc.
INSTALLATION INSTRUCTIONS
HORIZONTAL MOUNT - ROOF TOP CONFIGURATION
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WARNING:
Due to the size and weight of this equipment, it is
recommended that the heater support structure be
reviewed and approved by a qualified structural engi-
neer and the roof manufacturer before installing this
equipment.
IMPORTANT
Before proceeding with the installation, verify the fea-
sibility of the location selected with respect to acces-
sibility to the equipment for service and maintenance
functions.
IMPORTANT
To minimize snow and rain ingestion, position the heat-
er inlet opposite the prevailing wind.
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CAUTION:
To prevent contaminated air from being drawn into
the heater, install the heater’s inlet at least 10 feet
from any building exhaust, process exhaust, sewer
stacks, or other sources that would allow contami-
nants to be drawn into the heater. Consult local
codes for applicable building code provisions for
ventilation air.
IMPORTANT
For model M140 heaters, refer to the “Field Assembly
Instructions” worksheets included with this manual for
detailed heater assembly directions.
1. Prepare the roof for installation. (See pages 10-12
for roof opening dimensions for your specific
heater.) The gas and electrical connections must not
penetrate the unit base or mounting curb. Cambridge
Engineering recommends using pitch pockets or
decktite to seal the penetrations.
IMPORTANT
Accurate measurements are critical and will affect in-
stallation process.
2. Assemble and secure the roof curb to the support
structure per the recommendations of the structural
engineer and roof manufacturer.
IMPORTANT
The roof curb or support structure should be in-
stalled such that the heater will sit level. Cambridge
Engineering recommends mounting the heater 24" off
the roof surface in areas where snow accumulation
could impact heater operation.
3. Lower the discharge duct through the roof opening.
4. Install the roof curb gasket.
5. Use a crane or comparable lifting device to raise
and position the equipment. Block the heater where
necessary. Use a spreader bar to prevent damage and
connect slings to the lifting eyes.
6. Caulk all joints of the heater’s accessories installed
in the field. Use a clear or gray latex based polyure-
thane caulking to prevent water leaks.
7. Seal all roof penetrations to prevent roof leaks.
8. Install the discharge plenum, where used, by screw-
ing the plenum to the discharge duct. Install 4 hang-
ing rods from the ceiling supports to the plenum’s
support brackets.
