MITS AIR MOD31-24HFN1-MTOW Supplement

MITS AIRTM Inverter Compressor Matched System
Installation / Service Manual
MOD31-24HFN1-MTOW (2 Ton) + MVB-24HWFN1-M
MOD30U-36HFN1-MX (3 Ton) + MVB-36HWFN1-M
MOE30U-48HFN1-MX (4 Ton) + MVB-48HWFN1-M
Heat Pump Models (Outdoor + Indoor)

Page 1 of 35
Table of Contents
Important ......................................................................................................................... 2
Warning ........................................................................................................................... 2
Important Installation Considerations .......................................................................... 3-4
Refrigerant Gases ........................................................................................................... 4
Electrical Work Warnings ................................................................................................. 5
Outdoor Unit Installation .................................................................................................. 6
Extreme Weather Conditions ............................................................................... 7
Anchoring ............................................................................................................. 7
Bracketing ............................................................................................................. 8
Unit Dimensions & Clearances .......................................................................... 8-9
Wiring ................................................................................................................. 10
Refrigerant Tubing Connection ...................................................................................... 11
Connection Instructions ................................................................................. 11-13
Instructions for Connecting Flares ...................................................................... 13
Pressure Testing & Evacuation ................................................................................. 14-15
Connecting Piping ............................................................................................... 16
Evacuation and Opening the System ............................................................. 17-18
Test Run ........................................................................................................................ 18
Indoor Unit Installation ................................................................................................... 19
Installation Instructions, Dimensions, & Duct Connections ............................ 20-21
Mount Positions ............................................................................................. 21-23
Installation of Electric Auxiliary Heat Module ................................................. 24-25
Drainpipe Installation ..................................................................................... 26-27
Startup Form .................................................................................................................. 28
Wiring Diagrams ....................................................................................................... 29-31
Additional Refrigerant Charge Chart .............................................................................. 32
Unit Data ........................................................................................................................ 33
Notes ............................................................................................................................. 34
Limited Warranty ........................................................................................................... 35

Page 2 of 35
Important: Legislation for Compliance within Canada
This manual is intended for use by personnel qualified by Federal, Provincial, and
Municipal licensing in Canada and skill recognitions as required in the jurisdiction in
which the equipment is being installed. Appropriate permits must be taken out as
required in that jurisdiction in which the equipment is being installed and reporting of
installation as required by law are the responsibility of the installer or contractor as
obligated by law.
The installation must conform and comply with all applicable Federal, Provincial, and
Municipal statutes, regulations, codes, ordinances, and bylaws in Canada. These take
precedence over this manual.
Leak testing must be done in compliance with all applicable Federal, Provincial, and
Municipal statutes, regulations, codes, ordinances, and bylaws in Canada. If you are
unsure of your requirements, consult your local authority having jurisdiction.
All installation and service work must be completed by qualified and appropriately
licensed individual in accordance with all Federal, Provincial, and Municipal statutes,
regulations, codes, ordinances, and bylaws in Canada.
Read safety precautions and review instructions before starting installation!
Incorrect installation due to ignoring instructions can cause serious damage or injury.
The seriousness of potential damage or injuries is classified as either a WARNING or
CAUTION.
WARNING
•Do not use an extension cord to power the unit.
•Do not share the electrical circuit with any other appliance. Improper or
insufficient power supply can cause fire, electrical shock, or failure.
•When connecting refrigerant piping, do not allow contamination of the line set.
The presence of other gases or substances will lower the unit capacity, and can
cause abnormally high pressure in the refrigeration cycle. This can cause
explosion and injury.
•Do not allow children to play with the air conditioner. Children must be
supervised around the unit at all times.

Page 3 of 35
Important Installation Considerations
1. The metering device must be removed from the indoor coil.
2. The liquid line and the gas line from the outdoor unit to the indoor coil must be
insulated.
3. The thermostat must be used or configured as a 2 stage heat cool thermostat
and the furnace type is “Electric Furnace” to ensure the fan comes on with the
first stage heat. You may wire two stage cooling to utilize fan speed changed on
EC motor systems.
4. The interface box power wiring must be wired with approved cabling complying
with the Canadian Electrical Code and the Provincial Electrical code in which the
equipment is being installed. The power wiring must comply with the wiring type
and applicable conduits as required by these codes.
5. All wiring and installation work must be properly arranged to ensure that the
control board cover can close properly. If the control board cover is not closed
properly, it can lead to corrosion and cause the connection to fail.
6. For all electrical work, follow all local and national wiring standards, regulations,
and the Installation Manual. An independent circuit to supply power must be
used. Do not connect other appliances to the same circuit. Insufficient electrical
capacity or defects in electrical work can cause electrical shock or fire or cause
the appliance to fail.
7. For all electrical work, use the specified cables and conform to all applicable
codes and ordinances. Improper electrical connections can overheat and cause
fire, and may also cause shock.
8. Installation must be performed by an authorized dealer or specialist that is
licensed under all applicable statues, regulations, codes, ordinances, and
bylaws.
9. Installation must be performed according to the installation instructions. Improper
installation can cause water leakage, electrical shock, or fire. Equipment must be
installed in accordance with applicable building codes, ordinances, B51, B52, the
Canadian Electrical Code, and the Electrical Code of the Province in which the
system is installed.
10.An authorized and appropriately licensed service technician must be contacted
for repair or maintenance of this unit.
11.Only use the included accessories, parts, and specified parts for installation.
Using non-standard parts can cause water leakage, electrical shock, fire, and
can cause the unit to fail.
12.Install the unit in a firm location that can support the unit’s weight. If the chosen
location cannot support the unit’s weight, or the installation is not done properly,
the unit may drop and cause serious injury and damage.

Page 4 of 35
CAUTION
Do not install the unit close to an electrical or gas meter as regulated in the jurisdiction
where the equipment is being installed.
Do not install the unit in a location that may be exposed to combustible gas leaks. If
combustible gas accumulates around the unit, it may cause fire.
The product must be properly grounded at the time of installation, or electrical shock
may occur.
Note About Fluorinated Refrigerant Gases
1. This air conditioning unit contains fluorinated gases. For specific information on
the type of gas and the amount, please refer to the label on the unit itself.
2. Installation, service, maintenance, and repair of this unit must be performed by a
certified technician licensed to do so under all applicable Federal, Provincial, and
Municipal laws within Canada.
3. Product uninstallation and recycling must be performed by a certified technician
in accordance with applicable Federal, Provincial, and Municipal requirements
within Canada.
4. When the unit is checked for leaks, proper record-keeping of all checks is
strongly recommended.
5. Leak testing and leak testing certificates that are required in the jurisdiction
where the equipment is installed is the responsibility of the installer or the
contractor as required by law.

Page 5 of 35
BEFORE PERFORMING ELECTRICAL WORK, READ BELOW:
1. All wiring must comply with local and national electrical codes, and must be
installed by a licensed electrician.
2. All electrical connections must be made according to the Electrical Connection
Diagram located on the panels of the interface and outdoor units.
3. If there is a serious safety issue with the power supply, stop work immediately.
Explain your reasoning to the client and refuse to install the unit until the safety
issue is properly resolved.
4. Power voltage should be within 90-110% of rated voltage. Insufficient power
supply can cause malfunction, electrical shock, or fire.
5. Install a CSA certified surge protector where there is a possibility of power surges
or lightening strikes.
6. If connecting power to fixed wiring, install a surge protector and line of sight
disconnect switch with a horsepower capacity exceeding the range of the unit.
7. Only connect the unit to a dedicated branch circuit. Do not connect another
appliance to that outlet.
8. All wiring must be installed in accordance with the Canadian Electrical Code or
the Provincial Electrical Code applicable to the jurisdiction that the equipment is
being installed. The contractor is responsible for any required permits.
9. Make sure to properly ground the air conditioner.
10.Every wire must be firmly connected. Loose wiring can cause the terminal to
overheat, resulting in product malfunction and possible fire.
11.Do not let wires touch or rest against refrigerant tubing, the compressor, or any
moving or vibrating parts within the unit.

Page 6 of 35
Step 1: Select installation location before installing the
outdoor unit. The following are standards that will
assist with choosing an appropriate location for the
unit. Proper installation locations must meet the
following standards:
✓Meets all spatial requirements shown in
Installation Space Requirements (refer to
Fig. 4.1).
✓Good air circulation and ventilation
✓Firm and solid –the location can support the
unit and will not vibrate.
✓Noise from the unit will not disturb others.
✓Protected from prolonged periods of direct
sunlight, rain, or snow.
DO NOT install the unit in the following locations:
Near an obstacle that will block air inlets and outlets.
Near a public street, crowded areas, or where noise from the unit will disturb
others.
Near animals or plants that will be harmed by hot air discharge.
Near any source of combustible gas or in a location that is exposed to large
amounts of dust.
In a location exposed to excessive amounts of salty air
Outdoor Unit Installation

Page 7 of 35
If the unit is exposed to prevailing winds:
Install the unit so that air outlet is at a 90° angle to
the direction of the wind. If needed, obtain wind
baffles from your distributor to protect the unit from
extremely heavy winds. See 4.2 and Fig. 4.3.
Anchor Outdoor Unit
The outdoor unit can be anchored to the ground or to a wall-
mounted bracket.
For cooling only units, if the unit is installed on the
ground or on a concrete mounting platform, do the
following:
1. Mark the positions for 4 expansion bolts required.
2. Pre-drill holes for expansion bolts.
3. Clean concrete dust away from holes.
4. Place a nut on the end of each expansion bolt.
5. Hammer expansion bolts into the pre-drilled holes.
6. Remove the nuts from the expansion bolts, and place
outdoor unit on bolts.
7. Put washer on each expansion bolt, then
replace the nuts.
8. Using a wrench, tighten each unit until snug.
9. Heat pumps must be elevated off grade / roof
minimum 18” to ensure proper winter operation
during defrost cycle.
Caution: Heat pumps must be installed on a
properly designed stand and have minimum
18” clearance from normal snow levels in the
area.
Systems being installed in close proximity to
salt water or other corrosive substances must
be specially coated to prevent corrosion.
Contact your distributor for guidance.
WHEN DRILLING INTO THE
CONCRETE, EYE PROTECTION
IS REQUIRED AT ALL TIMES!
Special Considerations for Extreme Weather Conditions

Page 8 of 35
CAUTION
Installing the unit on a wall-mounted bracket:
1. Mark the position of bracket holes based as needed.
2. Pre-drill the holes for the expansion bolts.
3. Clean dust and debris away from holes.
4. Place a washer and a nut on the end of each expansion bolt. Thread expansion
bolts through holes in mounting brackets, put mounting brackets in position, and
hammer expansion bolts into the wall.
5. Check that the mounting brackets are level.
6. Carefully lift unit and place its mounting feet on brackets.
7. Bolt the unit firmly to the brackets.
Model
Unit
Dimensions
W
D
H
W1
A
B
MOD31-24HFN1-MTOW
Inches
37.24
16.14
31.89
40.6
26.5
15.9
MOD30U-36HFN1-MX
Inches
37.24
16.14
31.89
40.6
26.5
15.9
MOE30U-48HFN1-MX
Inches
37.48
16.34
52.48
41.1
25.0
15.9
Unit Dimensions
Before installing a wall-mounted unit, make sure that the wall is made of solid brick,
concrete, or of similarly strong material (load bearing wall).
The wall must be able to support at least 4 times the weight of the unit.
W1
W
H
A
D
B
A
D
W1
B
H
W

Page 9 of 35
Minimum Clearance For Outdoor Unit
Multiple Unit Clearances for Outdoor Units

Page 10 of 35
1. Prepare the cable for connection:
a. Using wire strippers, strip the rubber jacket from both ends of cable to
reveal about 40mm (1.57 in) of the wires inside.
b. Strip the insulation from the ends of the wires.
c. Using a wire crimper, crimp a CSA certified fork terminal on the ends of
the wires.
2. Unscrew the electrical wiring cover and remove it. Unscrew the cable clamp
below the terminal block and place it to the side.
3. Match the wire colours/labels with the labels on the terminal block, and firmly
screw the lug screw to the wire and its corresponding terminal.
4. After checking to make sure every connection is secure, make a drop loop with
the wires to prevent rainwater from flowing into the terminal.
5. Using the cable clamp, fasten the cable to the unit. Screw the cable clamp down
tightly.
6. Insulate unused wires with a wire nut and PVC electrical tape. Arrange them so
that they do not touch any electrical or metal parts.
7. Replace the wire cover on the side of the unit, and screw it in place.
8. Refer to pages 29, 30, and 31.
CAUTION
ALL PORTIONS OF THE CANADIAN ELECTRICAL CODE OR THE PROVINCIAL
ELECTRICAL CODE IN WHICH THE EQUIPMENT IS INSTALLED IN, MUST BE
FOLLOWED. WIRE SIZING AND TYPE, MECHANICAL PROTECTION AND
WEATHER PROOFING TAKES PRECEDENCE OVER THIS MANUAL.
A LINE OF SIGHT DISCONNECT AT THE OUTDOOR UNIT MUST BE USED FOR
THE POWER COMING FROM THE DISTRIBUTION BOX, IT MUST HAVE A
CERTIFIED HORSE POWER RATING EXCEEDING THE OUTDOOR UNIT RATING.
REQUIRED PERMITS ARE THE RESPONSIBILITY OF THE CONTRACTOR
PERFORMING THE WORK.
BEFORE PERFORMING ANY ELECTRICAL OR WIRING WORK, TURN OFF THE
MAIN POWER TO THE SYSTEM.
ALL WIRING MUST BE PERFORMED STRICTLY IN ACCORDANCE WITH THE
LOCAL CODE WITHIN CANADA.

Page 11 of 35
Note on Pipe Length:
The length of refrigerant piping will affect the performance and energy efficiency of the
unit. Nominal efficiency is tested on units with a pipe length in North America of 7.5 m
(25’).
A minimum pipe run of 3 meters (10 ft) is required to minimize vibration and
excessive noise.
Refer to the table below for specifications on the max length and drop height of piping.
Model
Capacity (Btu/hr)
Max Length
Max Height
ft
M
ft
m
R401A Inverter
Split Air
Conditioner
> 24,000 and < 35,000
164
50
82
25
> 36,000 and < 48,000
213
65
98
30
Step 1: Cut Tubing
When preparing refrigerant pipes, take extra care to cut and flare them properly. This
will ensure efficient operation and minimize the need for future maintenance.
1. Measure the distance between the indoor and
outdoor units.
2. Using a tube cutter, cut the pipe a little longer than
the measured distance.
3. Make sure that the tube is cut at a perfect 90° angle.
Refer to Fig. 5.1 for bad cut examples.
Be extra careful not to damage, dent, or deform the tube
while cutting. This will drastically reduce the efficiency of
the unit.
Refrigerant Tubing Connection
Maximum Length and Drop Height of Refrigerant Piping per Unit Model
Connection Instructions –Refrigerant Tubing
DO NOT DEFORM
TUBE WHILE CUTTING

Page 12 of 35
Step 2: Remove Burrs
Burrs can affect the air-tight seal of refrigerant piping
connection. They must be completely removed.
1. Hold the pipe at a downward angle to prevent burrs from
falling into the tubing.
2. Using a reamer or deburring tool, remove all burrs from
the cut section of the tubing.
3. Take care not to score the wall during deburring. This will
cause a leak.
Step 3: Flare Tubing Ends
Proper flaring is essential to achieve an airtight seal.
1. After removing burrs from cut tube, seal the ends with PVC
tape to prevent foreign materials from entering the tube.
2. Sheath the tubing with insulating material.
3. Place flare nuts on both ends of tubing. Make sure they are
facing in the right direction, because they cannot be put on
or have their direction changed after flaring. See Fig. 5.3.
4. Remove PVC tape from ends of the tub when ready to
perform flaring work.
5. Clamp flare form on the end of the tube. The end of the tube
must extend beyond the edge of the flare form in accordance
with the dimensions shown in the table below. See Fig. 5.4.
Fig. 5.5.

Page 13 of 35
CAUTION –DO NOT USE EXCESSIVE TORQUE
Step 4: Connect Tubes
When connecting refrigerant tubing, be careful not to use excessive torque or to deform
the tubing in any way. First connect the low-pressure pipe, then the high-pressure lines.
1. Align the center of the two tubes that will connect.
See Fig. 5.7.
2. Tighten the flare nut as tightly as possible by hand.
3. Using a spanner, grip the nut on the unit tubing.
4. While firmly gripping the nut on the unit tubing, use
a torque wrench to tighten the flare nut according to
the torque valves in the Torque Requirements
table below. Loosen the flaring. See Fig 5.8.
Repeat Steps 3 to 6 for the remaining pipe.
Torque Wrench Specification
Tubing Size
Torque
IN
mm
Wrench
Size (mm)
N-M
ft-lb
3/8
9.52
22
34-42
25-30
5/8
15.88
26
68-82
49-59
MINIMUM BEND RADIUS
When bending connective refrigerant tubing, the
minimum bending radius is 10 cm. See Fig. 5.6.
Excessive force can break the nut or damage the refrigerant tubing. Torque
requirements must not exceed values as shown in the table below.
Instructions for Connecting Flares

Page 14 of 35
Ensure the maximum test pressure of your indoor coil. Under no circumstances
should the testing exceed 450 psig!
The appropriate personal safety protection equipment including gloves and safety
glasses must be worn at all times.
Pressure test the system using dry nitrogen:
1. Secure the pressure gas tank securely to ensure it does not fall over and
damage the regulator or hoses.
2. Install a nitrogen regulator certified for pressures exceeding the test and ensure
the connection nut is adequately torqued.
3. Open the regulator output pressure knob so that it is loose.
Pressure Testing and Evacuation
This procedure is intended for professionals with appropriate certification and
licensing in the jurisdiction that the equipment is installed in. This procedure requires
the use of high-pressure gasses that if incorrectly used can cause injury and death.

Page 15 of 35
4. Connect your manifold center hose to the regulator and your high-pressure hose
to the machine. You will require a 1/4” to 5/16” hose adaptor to do this.
5. Open the main high pressure valve of the tank and ensure that the regulator is
not leaking. Begin closing the output pressure of the regulator to begin delivering
nitrogen to the hoses, and stop at 75 psig.
6. Slowly open the high pressure of the manifold and slowly fill the lines to 75 psig.
Mark your gauge cover with a pencil indicating the leading edge of the gauge
needle, turn off the main valve of the tank and wait 10 minutes.
7. If the needle has not indicated a pressure drop, open your main valve and slowly
open the high pressure to increase the pressure to 150 psig. Shut off the main
valve and mark the needle position with your pencil and hold for 10 minutes.
8. If there is no pressure drop, open the main valve and increase to 400 psig. Close
the main valve and mark the manifold pressure gauge with a pencil.
9. If the pressure has not dropped after 35 minutes, slowly release the nitrogen to
atmosphere and go to the evacuation procedure.
10.If there has been a pressure drop, use an approved leak detection sap solution to
find the leak. Do not shake the solution before use! This will introduce bubbles to
the solution and make leak detection impossible.
11.Repair the leak and repeat this procedure until leak(s) have been eliminated.

Page 16 of 35
USE WRENCH TO GRIP MAIN BODY OF VALVE
1. Unscrew the cover from the packed valve on the
side of the outdoor unit (see Fig. 5.9).
2. Remove protective caps from ends of valves.
3. Align flared tubing end with each valve, and
tighten the flare nut as tightly as possible by
hand.
4. Using a properly sized wrench, grip the body of
the valve. Do not grip the nut that seals the
service valve (see Fig. 5.10).
5. While firmly gripping the body of the valve, use a
torque wrench to tighten the flare nut according
to the correct torque values.
6. Loosen the flaring nut slightly, then tighten again.
Repeat Steps 3 to 6 for the remaining pipe.
Torque Wrench Specification
Tubing Size
Wrench Size
Torque
IN
mm
mm
N-M
ft-lb
3/8
9.52
22
34-42
25-30
5/8
15.88
26
68-82
49-59
Instructions for Connecting Piping to Outdoor Unit
Excessive torque can damage the valve, flare nuts, tubing, and snap off other parts
of the valve.

Page 17 of 35
Preparations and Precautions
•Air and foreign matter in the refrigerant circuit can cause abnormal rise in
pressure, which can damage the air conditioner, reduce its efficiency, and cause
injury.
•Use a vacuum pump and manifold gauge to evacuate the refrigerant circuit,
removing any condensable gas and moisture from the system.
•Evacuation should be performed upon initial installation and when unit is
relocated.
Instructions
1. Connect the charge hose of the manifold gauge to service port on the outdoor
units low pressure valve. Use the spare port to mount the micron gauge. Keep
the micron gauge above the manifold to prevent oil from contaminating the
sensor.
2. Connect charge hose from the manifold gauge central port to the vacuum pump.
3. Open both ports of the manifold gauge.
4. Turn on the vacuum pump to evacuate the system.
5. Run the vacuum for at least 15 minutes after the micron gauge reads 350
microns.
6. Close the isolation valve of the manifold, and turn off the vacuum pump and
observe the micron gauge.
7. Wait for 10 minutes then check that there has been no change in system
pressure.
8. If there is a change in system pressure, refer to Gas Leak Check section for
information on how to check for leaks. If there is no change in system pressure,
proceed to the next section.
Evacuation and Opening System

Page 18 of 35
Opening the System
1. If the one-way length of refrigerant liquid line is
greater than twenty-five feet (25’), consult the charge
sheet in the rear of the manual and weigh in the
charge adjustment. Refer to page 33.
2. Remove the cap of the gas line stop valve. Use a
metric Allen key to open the valve and rotate the
valve stem to its maximum opening. Finger tighten
the cap back in place. Using a torque wrench, torque
the cap to its specified setting.
3. Repeat the process for the liquid line stop valve.
4. Remove the charge hose from the service port and
finger tighten the cap. Torque to the specified setting.
Stop Valve Torque Settings
Item
ft-lbs
Nm
kgf/cm
Line Port Cap
10-13
13.7 –17.7
140 –180
Stop Valve Cap
15-22
19.6 –29.4
200 –300
Only perform test run after the following steps have been completed:
•Electrical Safety Checks –Confirm that the unit’s electrical system is safe and
operating properly.
•Gas Leak Checks –Check all flare nut connections and confirm that the system
is not leaking.
•Valves –Confirm gas and liquid (high and low pressure) valves are fully open.
Run the system for 30 minutes.
Test Run
Before Test Run
Note: Use a metric Allen key only.
SAE keys are similar in size and
will damage the valve.

Page 19 of 35
•Securely install the indoor unit on a structure that can sustain its weight. If the
structure is too weak, the unit may fall and cause personal injury, unit and
property damage, or death.
•DO NOT install the indoor unit in a bathroom or laundry room as excessive
moisture can short the unit and corrode the wiring.
CAUTION
DO NOT install the unit in the following locations:
Areas with oil drilling or fracking
Coastal areas with high salt content in the air
Areas with caustic gases in the air, such as near hot springs
Areas with power fluctuations, such as factories
Enclosed spaces, such as cabinets
Areas with strong electromagnetic waves
Areas that store flammable materials or gas
Rooms with high humidity, such as bathrooms or laundry rooms
Indoor Unit Installation
Indoor Unit Parts
Safety Precautions