Cambridge Air Solutions M Series User manual

M-SERIES
DRAW THRU
DIRECT GAS-FIRED
MAKE-UP AIR HEATERS
TECHNICAL MANUAL
M-TM2-0120
WARNING:
Improper installation, adjustment, alteration, service or maintenance can cause property
damage, injury or death. Read the installation, operating, and maintenance instructions
thoroughly before installing or servicing this equipment.
FOR YOUR SAFETY
The use and storage of gasoline or other flammable vapors and liquids in open containers in
the vicinity of this appliance is hazardous.
FOR YOUR SAFETY
If you smell gas:
1. Open windows.
2. Don’t touch electrical switches.
3. Extinguish any open flame.
4. Immediately call your gas supplier.
Made in the USA
®
90.1
ASHRAE
ASHRAE
COMPLIANT
COMPLIANT
®

LIMITED WARRANTY
Cambridge Air Solutions Limited Warranty is included within the Terms and Conditions that are sent
with every Order Acknowledgement. For questions regarding Limited Warranty, contact Cambridge Air
Solutions Customer Service Group at 1-800-473-4569.
Copyright © 2019
Cambridge Air Solutions
All Rights Reserved
Cambridge Air Solutions
760 Long Road Crossing Dr.
Chesterfield, MO. 63005
Phone: [phone]
Fax: [phone]
www.cambridgeair.com

M-SERIES
TECHNICAL MANUAL
HAZARD SUMMARY............................................................................................................... 4
TYPICAL SYSTEM OVERVIEW ............................................................................................. 5
Accessory Identification .................................................................................................... 6
Heater/Accessory Weights ................................................................................................. 7
Heater Operation................................................................................................................ 8
Heater Configuration ......................................................................................................... 8
INSTALLATION INSTRUCTIONS
Uncrating Instructions........................................................................................................ 9
Mounting Location............................................................................................................. 9
Horizontal Mount – Mounting Curb................................................................................ 10
Horizontal Mount – Roof Top Configuration .................................................................. 10
Horizontal Mount – Outdoor Stand Mount Configuration .............................................. 15
Horizontal Mount – Thru Wall Configuration ................................................................. 18
Vertical Mount – Outdoor Configuration......................................................................... 21
Vertical Mount – Indoor Configuration ........................................................................... 25
Gas Piping........................................................................................................................ 28
Electrical .......................................................................................................................... 29
START-UP INSTRUCTIONS................................................................................................... 30
VFD Start-Up Instructions............................................................................................... 37
OPERATING INSTRUCTIONS
Operating Sequence ......................................................................................................... 44
Electronic Thermostat...................................................................................................... 45
TSS Controller ................................................................................................................. 47
BACnet Controller........................................................................................................... 56
MAINTENANCE INSTRUCTIONS
Bearing Lubrication ........................................................................................................ 60
Belt Tensioning ............................................................................................................... 60
Blower Cleaning .............................................................................................................. 61
Burner Cleaning............................................................................................................... 61
Gas Valve Cleaning.......................................................................................................... 61
ASCO Gas Valves ............................................................................................................ 62
Filters ............................................................................................................................... 64
CONTENTS

Cambridge Air Solutions. 2 M-Series Technical Manual
DIRECT EVAPORATIVE COOLING (DEC)
Safety Considerations ...................................................................................................... 66
Receiving ......................................................................................................................... 67
Installation........................................................................................................................ 67
Plumbing/Fill and Drain Valves................................................................................. 68
Auto Drain with Freeze Protection (Optional)........................................................... 68
Fill and Drain Valve Schematic ....................................................................................... 69
Drain, Overflow and Make-up Water Piping for Autodrain with Freeze Protection . 70
Fill Valve Schematic .................................................................................................. 70
Electrical Panel/Wiring .................................................................................................... 71
Media Cooling Pads Operating Installation..................................................................... 72
Munters CELdek........................................................................................................ 72
Initial Start-Up ................................................................................................................. 73
Procedure ................................................................................................................... 73
Normal Operations........................................................................................................... 74
Sequence of Operations ................................................................................................... 74
Maintenance..................................................................................................................... 74
Procedure ................................................................................................................... 74
REFERENCE
Heater Roof and Wall Openings ...................................................................................... 75
Heater Discharge Dimensions.......................................................................................... 75
Gas Train Drawings ......................................................................................................... 76
Electrical Control Enclosure Isometric Drawings ........................................................... 78
M110 – M115............................................................................................................. 78
M118 – M136 ............................................................................................................ 79
M140.......................................................................................................................... 80
M-SERIES
TECHNICAL MANUAL
CONTENTS

M-Series Technical Manual 3 Cambridge Air Solutions
M-SERIES
TECHNICAL MANUAL
CONTENTS
REFERENCE CONT'D
Electrical Wiring Diagrams.............................................................................................. 81
Series 14..................................................................................................................... 81
Series 14 Kitchen Ventilation System........................................................................ 82
Series 44 M140 .......................................................................................................... 83
Series 44 Tamperproof Controls /Operating Thermostat........................................... 84
Series 44 Temperature Setback System/Temperature Averaging............................... 85
Series 44 Tamperproof Controls/ Variable Frequency Drive/ Room Pressure .......... 86
Connection Diagram ........................................................................................................ 87
Gas Control Systems........................................................................................................ 88
Remote Control Station Components .............................................................................. 89
Individual Heater Component Descriptions..................................................................... 91
Damper Motor Replacement & Adjustment .................................................................... 95
Troubleshooting Guide .................................................................................................... 97
ANSI/ASHRAE/IESNA STANDARD 90.1 ........................................................................... 103
MAINTENANCE LOG.......................................................................................................... 104
QR CODE ............................................................................................................................... 109

Cambridge Air Solutions. 4 M-Series Technical Manual
HAZARD SUMMARY
The following safety precautions apply to the
installation, operation, and maintenance of the equipment
described by this technical manual.
WARNING:
Any unauthorized modification of this equipment
shall void the warranty.
WARNING:
Only qualified personnel should attempt
installation, service, and repair of this equipment.
Use extreme caution and observe safety
regulations at all times. Obey applicable plant and
OSHA safety regulations.
WARNING:
Recirculation of room air is not permitted.
Adequate building relief shall be provided so as to not
over-pressurize the building when the make-up air
heating system is operating at its rated capacity. It should
be noted that this can be accomplished by taking into
account, through standard engineering methods, the
structure’s designed infiltration rate, by providing
properly sized relief openings, by interlocking a powered
exhaust system, or by a combination of these methods.
If the failure or malfunction of this heater creates a
hazard to other fuel burning equipment in the building
(e.g. when the heater is providing the make-up air to a
boiler room), the heater is to be interlocked to open inlet
air dampers or other such devices.
If the heater is installed such that an inlet duct is
utilized, the duct system must be purged with at least
four air changes prior to an ignition attempt.
IMPORTANT
Installation in Aircraft Hangars
Refer to the Standard for Aircraft Hangars, ANSI/
NFPA 409, for specific information on the installation
requirements for these heaters in airplane hangars.
IMPORTANT
Installation in Parking Garages
Refer to the Standard for Parking Structures, ANSI/
NFPA 88A, or the Standard for Repair Garages, ANSI/
NFPA 88B, for specific information on the installation
requirements for these heaters in public garages.
If in doubt regarding installation or application,
contact Cambridge Air Solutions Customer Service
Group at 800-473-4569 during the hours of 8:00 a.m.
to 5:00 p.m. Central Time, Monday through Friday.
Hazard Identification
Warnings and Cautions appear at appropriate sections throughout this manual. Read these carefully.
WARNING: Indicates a potentially hazardous situation which could result in
death or serious injury.
CAUTION: Indicates a potentially hazardous situation which may result in
minor or moderate injury. It may also be used to alert against
unsafe practices.
CAUTION: Indicates a situation that may result in accidents with equipment or
property damage only.

M-Series Technical Manual 5 Cambridge Air Solutions
TYPICAL SYSTEM OVERVIEW
CONTROL SYSTEMS:
MAXITROL SERIES 14
The Maxitrol Series 14 electronic discharge temperature
control system maintains a constant discharge
temperature. The standard control permits manual
adjustment of discharge temperature (55° to 90°F) from
inside the heater control enclosure. As an option, a
Remote Heat Adjust control with override capability to
130°F can be provided to allow manual adjustment of
discharge temperature (55° to 130°F) from either inside
the heater control enclosure or in the Remote Control
Station.
MAXITROL SERIES 14 WITH SPACE
THERMOSTAT
The Maxitrol Series 14 modulation controls function
as described above using the optional Remote Heat
Adjust control in conjunction with an electronic
space thermostat switch contact to increase discharge
temperature. The discharge temperature will increase
to a preset rise (0°F to 40°F) above the set point on the
Remote Heat Adjust control face based on the setting of
the override temperature dial, which is visible from the
top of the control.
MAXITROL SERIES 44
The Maxitrol Series 44 modulation controls maintain a
constant space temperature by increasing or decreasing
the discharge temperature. The Space Temperature
Selector is set to maintain the space temperature of the
heated space by controlling the heater output between the
MIN and MAX setting on the amplifier. The MIN dial
setting determines the minimum discharge temperature the
heater will deliver (40°F to 80°F). The MAX dial setting
determines the maximum discharge temperature the
heater will deliver (80°F to 140°F).
MAXITROL SERIES 44 / TAMPER PROOF
The Maxitrol Series 44 / Tamper Proof temperature
control system is similar to the Maxitrol Series
44 controls above except the adjustable Space
Temperature Selector control is replaced by two other
controls. The adjustable portion of the temperature
selector is typically mounted in the Remote Control Station
to prevent unwanted tampering of the temperature setting and
the non-adjustable space sensor is mounted in the space
being heated.

Cambridge Air Solutions. 6 M-Series Technical Manual
TYPICAL SYSTEM OVERVIEW
ACCESSORY IDENTIFICATION
Horizontal Mount
Roof Top Configuration
Horizontal Mount
Outdoor Pad Mount Configuration
Horizontal Mount
Thru Wall Configuration
FSID
ML
FLOOR
IC
DRH
IE
FLASHING & TRI
M
BY OTHERS
UNIT
DP
Vertical Mount
Indoor Configuration
Vertical Mount
Outdoor Configuration
DD Discharge Duct
DE Discharge Elbow
DP Discharge Plenum
DRH Dual Rainhood w/ Inlet Screen & Filter Rack
FS Filter Section V-Bank
FSID V-Bank Filter Section/Inlet Damper Combo
HBDD Horizontal Blast Discharge Diffuser
IC Inlet Collar
IE Inlet Elbow
MC Mounting Curb
MDD Motorized Discharge Damper
MID Motorized Inlet Damper
ML Mounting Legs
SRH Single Rainhood w/ Inlet Screen
Component Identification

M-Series Technical Manual 7 Cambridge Air Solutions
HEATER / ACCESSORY WEIGHTS
Horizontal Mount (Weights Shown In Pounds)
Vertical Mount (Weights Shown In Pounds)
*Due to shipping constraints the M140 consists of a of blower module (3625 lbs.) and burner module (1720 lbs.)
**The burner module with integral Filter Section weighs 2380 lbs.
Model M110 M112 M115 M118 M120 M125 M130 M136 M140
Base Heater 425 440 550 1125 1395 2045 2475 2845 5345*
Rain Hood - Single 45 45 70 135 175 275 325 375 N/A
Rain Hood - Dual, Upper N/A N/A N/A 95 145 240 270 325 480
Rain Hood - Dual, Lower N/A N/A N/A 75 105 170 205 280 410
Filters for Rain Hood 10 10 15 20 30 45 60 80 90
Inlet Screen 5 5 10 10 15 25 35 40 45
Inlet Collar 40 40 50 85 110 170 200 230 335
Inlet Damper (internal) 25 25 35 55 65 125 155 210 290
V-Bank Filter Section 70 70 100 215 235 285 400 500 **
Discharge Duct - 20" 25 30 35 40 45 50 60 75 80
Discharge Duct - 50" 60 70 80 90 120 140 160 180 200
Discharge Duct - 72" 70 85 95 125 150 180 220 250 280
Discharge Damper (internal) N/A N/A N/A 30 30 35 45 55 75
Discharge Plenum 4-way 100 150 200 250 300 400 470 930 1480
Discharge Plenum 3-way 80 130 175 220 260 360 430 500 795
Discharge Splash Pan 40 40 40 60 60 60 80 80 80
Curb 14" 60 70 80 100 120 180 210 230 270
Curb 24" 100 120 140 170 200 270 310 340 445
Model M118 M120 M125 M130 M136
Base Heater 1800 2300 2900 3200 3600
Rain Hood - Single 135 175 275 325 500
Rain Hood - Dual, Upper 95 145 240 270 380
Rain Hood - Dual, Lower 75 105 170 205 275
Filters for Rain Hood 20 30 45 60 80
Inlet Collar 100 110 170 200 230
Inlet Elbow 450 500 780 1040 1325
Inlet Damper 305 345 400 475 490
V-Bank Filter Section 280 380 420 555 715
Filter Section/Inlet Damper Combo 470 600 670 860 920
Discharge Duct - 20" 40 45 50 60 75
Discharge Duct - 50" 90 120 140 160 180
Discharge Duct - 72" 125 150 180 220 250
Discharge Damper (internal) 35 35 40 60 75
Discharge Elbow 95 120 170 230 340
Discharge Plenum 3-way w/enclosure 280 320 420 510 580
Discharge Diffuser 210 230 280 310 350
Mounting Legs 3-foot, set of 4 250 250 250 250 250
Mounting Legs 5-foot, set of 4 400 400 400 400 400

Cambridge Air Solutions. 8 M-Series Technical Manual
HEATER CONFIGURATION
Cambridge M-Series Draw-Thru heaters provide
fresh air ventilation to a facility, provide tempered air
to replace the air that is mechanically exhausted, or
address cold drafts from natural infiltration. Heater
operation is typically electrically interlocked with
mechanical exhaust fans, manually operated switches,
programmable timers, or other process control
systems. The discharge temperature of heaters with
fixed discharge temperature controls is typically set
10°F to 20°F above the desired space temperature.
The entering air thermostat acts as an economizer by
deactivating burner operation during mild weather.
TYPICAL SYSTEM OVERVIEW
HEATER OPERATION
MANUAL SHUT-OFF VALVE
BURNER VIEWPORT
MANUAL SHUT-OFF VALVE
ELECTRICAL / GAS CONTROL ENCLOSURE
SAFETY SHUT-OFF VALVE (SSV)
SHUT-OFF VALVE (SOV)

M-Series Technical Manual 9 Cambridge Air Solutions
INSTALLATION INSTRUCTIONS
UNCRATING INSTRUCTIONS
1. Verify the number of items on the Bill of Lading
versus the number of items received.
2. Check for shipping damage. If damage is found,
immediately file a claim with carrier before
proceeding further. Take photographs of any
damage.
3. Check items received to make sure they agree with
ordering information including verification of data
on the make-up air heater nameplate.
IMPORTANT
Do not discard any components or accessories.
MOUNTING LOCATION
Verify feasibility of the installation location selected
with respect to accessibility to the heater for service
and maintenance functions. Ensure the positioning of
the heater does not inhibit fork truck operation, storage
rack access, or other operations within the facility.
Ensure the heater inlet and outlet are not blocked or
severely restricted, such that it would affect the rated
airflow through the heater or affect the desired air
distribution pattern of the heater. If upon review of the
proposed installation, a problem is discovered which
may be considered detrimental to the performance of
the heater, or restricts its serviceability, or deviates from
the instructions or drawings which may be provided,
it is the responsibility of the installer to communicate
that information to the person or persons responsible for
providing the installation instructions or drawings prior
to proceeding with the installation.
WARNING:
Where the mounting height of the heater is a
consideration, work platforms or service lifts
should be provided for accessibility to the
equipment for service and maintenance activities.
IMPORTANT
Field constructed intake accessories should be designed
to minimize the entry of snow
and rain.
IMPORTANT
Minimum clearance from the face of the electrical
control enclosure to surrounding grounded surfaces
for service activities is 42". Adequate clearance for
burner removal is also required, which is based on 42"
or the length of the burner + 12", whichever is greater.
Access for service functions is also required on the
opposite side of the make-up air heater from the control
enclosure for a minimum distance of 24".

Cambridge Air Solutions. 10 M-Series Technical Manual
7/8” TYP
"B" dimension is the width of the Filter Section
"C" dimension is the length of the wood
nailer in the Mounting Rail
REQUIRED FOR INSTALLATION OF FILTER SECTION.
REQUIRED FOR INSTALLATION OF FILTER SECTION.
FOR ROOF MOUNTING, GAS AND ELECTRICAL CONNECTIONS
MUST NOT PENETRATE UNIT BASE OR MOUNTING CURB.
PITCH POCKETS OR ROOF BOOTS (BY OTHERS) RECOMMENDED.
INSTALLATION INSTRUCTIONS
HORIZONTAL ROOF MOUNT - MOUNTING CURB
M110 - M136
(Shown for Roof Top Configuration - Downblast Application)
Model A B C
M110 30¾" 26 7/8" 48"
M112 30¾" 26 7/8" 48"
M115 30¾" 41 1/8" 60"
M118 31½" 48 5/8" 60"
M120 31½" 54 5/8" 72"
M125 31½" 66 5/8" 84"
M130 37 3/8" 88 3/8" 96"
M136 37½" 88 3/8" 96"
M140 N/A N/A N/A
Note: The V Bank Filter Section is an integral part
of the M140 cabinet, thus it does not require a
separate Mounting Stand/Rail.

M-Series Technical Manual 11 Cambridge Air Solutions
INSTALLATION INSTRUCTIONS
HORIZONTAL MOUNT - ROOF TOP CONFIGURATION
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
engineer and the roof manufacturer before installing
this equipment.
IMPORTANT
Before proceeding with the installation, verify the
feasibility of the location selected with respect
to accessibility to the equipment for service and
maintenance functions.
IMPORTANT
To minimize snow and rain ingestion, position the heater
inlet opposite the prevailing wind.
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
contaminants 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
and with the components 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
Air Solutions recommends using pitch pockets or
roof boots to seal the penetrations.
IMPORTANT
Accurate measurements are critical and will affect
installation 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 installed
such that the heater will sit level. Cambridge Air
Solutions recommends mounting the heater 24" off the
roof surface in areas where snow accumulation could
impact heater operation.
3. Install the roof curb gasket seal. See drawing on
page 8.
4. Lower the discharge duct through the roof opening.
5. Use a crane or comparable lifting device to raise
and position the equipment. 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 silicone caulking to
prevent water leaks.
7. Seal all roof penetrations to prevent roof leaks.
8. Install the discharge accessory, where used, by
screwing the plenum to the discharge duct. Install
4 hanging rods from the ceiling supports to the
accessory’s support brackets.
9. Adjust internal vibration isolators, if applicable, per
the setup instructions provided with this manual.

Cambridge Air Solutions. 12 M-Series Technical Manual
TYPICAL INSTALLATION
HORIZONTAL MOUNT - ROOF TOP CONFIGURATION
M110 - M115
Typical Curb and
Discharge Duct
Model W L
M110* 17¾" 17¾"
M112* 19¼" 19¼"
M115* 22¼" 22¼"
Roof Opening
Typical Curb and
Discharge Duct
* DIMENSIONS ALLOW FOR ¾"
CLEARANCE ON EACH SIDE

M-Series Technical Manual 13 Cambridge Air Solutions
Chestereld, Missouri
This is an instrument of service and is the sole property
of Cambridge Engineering, Inc. It may not be copied,
reproduced, or re-used on any other project without
agreement in writing from this company.
REVISION
No. Date
M118-M136 Roof Top Installation
Ecn Date
No. Ecn
ALL FORMED VIEW DIM'S MEASURED
FROM OUTSIDE UNLESS OTHERWISE NOTED.
WHERE USED:
REV NOW:
DATE:
1ASYMMETRICAL FEATURE
Mat:
Weight:
DWG:MDL:
DISCHARGE DUCT
DISCHARGE PLENUM
MOUNTING CURB
REMOTE CONTROL STATION
BURNER VIEWPORT
CONTROL WIRING
(BY OTHERS)
INCOMING POWER (BY OTHERS)
SEDIMENT TRAP (BY OTHERS)
HIGH PRESSURE REGULATOR (HPR)
HIGH PRESSURE SUPPLY TAP
HIGH PRESSURE SHUT-OFF VALVE
VENT WITH SCREEN
(LOCATE MIN 10FT FROM INTAKE)
HPR (OPTION)
ELECTRICAL/GAS CONTROL ENCLOSURE
HANGER BRACKET
VENT PIPE (BY OTHERS)
RAINHOODS
DISCHARGE DUCT
MOUNTING CURB
TYPICAL INSTALLATION
HORIZONTAL MOUNT - ROOF TOP CONFIGURATION
M118 - M136
Typical Curb and
Discharge Duct
Model W L
M118** 25½" 25½"
M120** 29½" 29½"
M125** 35" 35"
M130*** 42" 42"
M136*** 48" 48"
Roof Opening
** DIMENSIONS ALLOW FOR 1"
CLEARANCE ON EACH SIDE
*** DIMENSIONS ALLOW FOR 1½"
CLEARANCE ON EACH SIDE

Cambridge Air Solutions. 14 M-Series Technical Manual
Typical Curb and
Discharge Duct
Model W L
M140*** 55¼" 55¼"
Roof Opening
TYPICAL INSTALLATION
HORIZONTAL MOUNT - ROOF TOP CONFIGURATION
M140
*** DIMENSIONS ALLOW FOR 1½"
CLEARANCE ON EACH SIDE

M-Series Technical Manual 15 Cambridge Air Solutions
INSTALLATION INSTRUCTIONS
HORIZONTAL MOUNT - OUTDOOR STAND MOUNT CONFIGURATION
WARNING:
Due to the size and weight of this equipment, it
is recommended the heater support structure be
reviewed and approved by a qualified structural
engineer before installing this equipment.
IMPORTANT
Before proceeding with the installation, verify the
feasibility of the location selected for accessibility to
the equipment for service and maintenance functions.
IMPORTANT
To minimize snow and rain ingestion, position the
heater inlet opposite the prevailing wind.
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
contaminants 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 wall for installation. (See pages 14-15
for wall opening dimensions for your specific
heater.)
IMPORTANT
Accurate measurements are critical and will affect
installation process.
2. Assemble and secure the support structure per the
structural engineer’s recommendations.
IMPORTANT
The support structure should be installed such that the
heater will sit level.
3. Use a crane or comparable lifting device to raise
and position the equipment. Use a spreader bar to
prevent damage and connect slings to the lifting
brackets.
IMPORTANT
Cambridge Air Solutions recommends mounting the
heater a minimum of 24" off the mounting surface in
areas where snow accumulation could impact heater
operation.
4. Caulk all joints of the heater’s accessories installed
in the field. Use a clear or gray silicone caulking to
prevent water leaks.
5. Install the discharge duct through the wall opening.
6. Install fiberglass insulation in the gaps between the
wall opening and discharge duct. Apply enough
insulation material to accommodate the full
thickness of the wall.
7. Install finish trim pieces (by others) to the top, sides
and bottom of the discharge duct on both the inside
and outside wall surfaces.
8. Apply a bead of silicone caulk that best matches the
color of the exterior wall surface of the facility and/or
the color of the heater accessories at the joint between
the top discharge duct and outside wall surface. Make
certain this is a continuous bead and that it runs the
entire width of the duct. Caulk all other exposed joints.
9. Install the discharge accessory, where used, by
screwing the accessory to the discharge duct. Install
hanging rods (3/8") minimum from the ceiling
supports to the accessory’s support brackets.
10. For M140 installations, see the field assembly
drawings provided with components.
11. Adjust internal vibration isolation, if applicable, per
the setup instructions provided with this manual.

Cambridge Air Solutions. 16 M-Series Technical Manual
TYPICAL INSTALLATION
HORIZONTAL MOUNT - OUTDOOR STAND MOUNT
CONFIGURATION
M118 - M136
Typical Duct Interface
Model W L
M118*** 26½" 26½"
M120*** 30½" 30½"
M125*** 36" 36"
M130**** 43" 43"
M136**** 49" 49"
Wall Opening
*** DIMENSIONS ALLOW FOR 1½"
CLEARANCE ON EACH SIDE
**** DIMENSIONS ALLOW FOR 2"
CLEARANCE ON EACH SIDE

M-Series Technical Manual 17 Cambridge Air Solutions
TYPICAL INSTALLATION
HORIZONTAL MOUNT - OUTDOOR STAND MOUNT
CONFIGURATION
M140
Model W L
M140**** 56¼" 56¼"
Wall Opening
Typical Duct Interface
**** DIMENSIONS ALLOW FOR 2"
CLEARANCE ON EACH SIDE

Cambridge Air Solutions. 18 M-Series Technical Manual
INSTALLATION INSTRUCTIONS
HORIZONTAL MOUNT - THRU WALL CONFIGURATION
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
engineer before installing this equipment.
IMPORTANT
Before proceeding with the installation, verify the
feasibility of the location selected with respect
to accessibility to the equipment for service and
maintenance functions.
IMPORTANT
To minimize snow and rain ingestion, position the
heater inlet opposite the prevailing wind.
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
contaminants to be drawn into the heater. Consult
local codes for applicable building code provisions
for ventilation air.
1. Prepare the wall for installation. (See pages 17-18 for
wall opening dimensions for your specific heater.)
IMPORTANT
Accurate measurements are critical and will affect the
installation process.
2. Install heater support rods per the structural
engineer’s recommendations.
3. Use a crane or comparable lifting device to raise
and position equipment. Block the heater where
necessary. Use a spreader bar to prevent damage and
connect slings to the lifting brackets.
IMPORTANT
Cambridge Air Solutions recommends mounting the
heater’s rainhood a minimum of 24" off the ground or
other surfaces.
4. Apply washers and double lock nuts to secure
equipment on hanging rods. Note: The discharge end
of the heater should be raised slightly (1/8"above
level) to allow ingested moisture to drain from the
heater.
5. Apply shims at the bottom of the rainhood to take up
slack in the opening, leaving a small joint between
the top of the heater and the wall.
6. Install fiberglass insulation in the gaps between the
wall opening and the inlet collar. Apply enough
material to accommodate the full thickness of the
wall.
7. Install finish trim pieces (by others) to the top, sides
and bottom of the inlet collar on both the inside and
the outside wall surfaces.
8. Apply a bead of silicone caulk. Make certain this is a
continuous bead and that it runs the entire width of the
collar. Caulk all other exposed joints.
9. Install the discharge accessory, where used, by
screwing the accessory to the heater or to the
discharge duct, as applicable. Install hanging rods
(3/8") minimum from the ceiling supports to the
accessory’s support brackets.
10. For M140 installations, see the field assembly
drawings provided with components.
11. Adjust internal vibration isolation, if applicable, per
the setup instructions provided with this manual.
12. For drain trough installation, see the field installation
detail provided with the component.