MITSUBISHI ELECTRIC MSZ-GS18 Room Air Conditioners Instruction Manual

MITSUBISHI ELECTRIC MSZ-GS18 Room Air Conditioners

Product Information

Specifications

• Product Name: Branch Box
• Compatible with: PAC-MKA53BC (R410A outdoor unit) and PAC-MKA33BC (indoor use)
• Refrigerant Type: HFC R410A

Product Usage Instructions

Safety Precautions
Before installation, read and understand all safety precautions provided in the manual. Ensure to report to the supply authority before connecting to the system.

Installation Process

1. Mounting the Branch Box: Follow the instructions in the manual for proper mounting.
2. Installing Refrigerant Piping: Use tools and pipe components specified for use with refrigerant mentioned in the outdoor unit installation manual.
3. Electrical Work: Ensure proper electrical connections are made following local regulations and instructions provided.
4. Test Run: Perform a test run after installation to ensure normal operation.

Maintenance and Safety
After installation, explain safety precautions, usage, and maintenance to the customer. Provide both the Installation Manual and Operation Manual to the user for reference.

Frequently Asked Questions (FAQ)

• Q: What precautions should be taken during installation?
  A: Ensure to read all safety precautions, use specified tools and components, and follow installation instructions carefully to prevent hazards or damage.

• Q: Can intermediate connections be used with the Branch Box?
  A: It is recommended to connect the indoor units, outdoor units, and branch boxes directly without intermediate connections to avoid communication errors.

Safety precautions

• Before installing the unit, make sure you read all the “Safety precautions”.

• Please report to or take consent by the supply authority before connection to the system.

• Warning:
  Describes precautions that must be observed to prevent danger of injury or death to the user.

• Caution:
  Describes precautions that must be observed to prevent damage to the unit.

After installation work has been completed, explain the “Safety Precautions,” use, and maintenance of the unit to the customer according to the information in the Operation Manual and perform the test run to ensure normal operation. Both the Installation Manual and Operation Manual must be given to the user for keeping. These manuals must be passed on to subsequent users.
: Indicates a part that must be grounded.
Warning:
Carefully read the labels affixed to the main unit.

Warning:

• Ask a dealer or an authorized technician to install the unit.
• For installation work, follow the instructions in the Installation Manual and use tools and pipe components specifically made for use with refrigerant specified in the outdoor unit installation manual.
• This appliance is not intended for use by persons (including children) with reduced physical, sensory or mental capabilities, or lack of experience and knowledge, unless they have been given supervision or instruction con-cerning use of the appliance by a person responsible for their safety.
• Children should be supervised to ensure that they do not play with the ap-pliance.
• The unit must be installed according to the instructions in order to minimize the risk of damage from earthquakes, typhoons, or strong winds. An incorrectly installed unit may fall down and cause damage or injuries.
• The unit must be securely installed on a structure that can sustain its weight.
• If the air conditioner is installed in a small room, measures must be taken to prevent the refrigerant concentration in the room from exceeding the safety limit in the event of refrigerant leakage. Should the refrigerant leak and cause the concentration limit to be exceeded, hazards due to lack of oxygen in the room may result.
• Ventilate the room if refrigerant leaks during operation. If refrigerant comes into contact with a flame, poisonous gases will be released.
• All electric work must be performed by a qualified technician according to local regulations and the instructions given in this manual.
• Use only specified cables for wiring.
• The terminal block cover panel of the unit must be firmly attached.
• Use only authorized accessories and ask a dealer or an authorized technician to install them.
• The user should never attempt to repair the unit or transfer it to another location.
• After installation has been completed, check for refrigerant leaks. If refrigerant leaks into the room and comes into contact with the flame of a heater or portable cooking range, poisonous gases will be released.
• Be sure to connect the power supply cords and the connecting wires for the indoor units, outdoor units, and branch boxes directly to the units (no inter-mediate connections).
  Intermediate connections can lead to communication errors if water enters the cords or wires and causes insufficient insulation to ground or a poor electrical contact at the intermediate connection point.
  (If an intermediate connection is necessary, be sure to take measures to prevent water from entering the cords and wires.)

Caution:

• Make sure that the refrigerant pipes are well insulated to prevent condensation.
  Incomplete insulation may cause condensation on the surface of pipes, wetting of the ceiling, floor and other important properties.

• Do not use the unit in an unusual environment. If the air conditioner is installed in areas exposed to steam, volatile oil (including machine oil), or sulfuric gas, areas exposed to high salt content such as the seaside, the performance can be significantly reduced and the internal parts can be damaged.

• Do not install the unit where combustible gases may leak, be produced, flow, or accumulate. If combustible gas accumulates around the unit, fire or explosion may result.

• When installing the unit in a hospital or communications office, be prepared for noise and electronic interference. Inverters, home appliances, high-frequency medical equipment, and radio communications equipment can cause the air conditioner to malfunction or breakdown. The air conditioner may also affect medical equipment, disturbing medical care, and communications equipment, harming the screen display quality.

• Thermal insulation of the refrigerant pipe is necessary to prevent condensation. If the refrigerant pipe is not properly insulated, condensation will be formed.

• Place thermal insulation on the pipes to prevent condensation. If the drain pipe is installed incorrectly, water leakage and damage to the ceiling, floor, furniture, or other possessions may result.

• Do not clean the air conditioner unit with water. Electric shock may result.

• Tighten all flare nuts to specification using a torque wrench. If tightened too much, the flare nut can break after an extended period.

• Be sure to install circuit breakers, if not installed, electric shock may result.

• For the power lines, use standard cables of sufficient capacity. Otherwise, a short circuit, overheating, or fire may result.

• When installing the power lines, do not apply tension to the cables. If the connections are loosened, the cables can snap or break and overheating or fire may result.

• Do not connect the ground wire to gas or water pipes, lighting rods, or telephone grounding lines. If the unit is not properly grounded, electric shock may result.

• Do not turn off the breaker of the M-NET Branch Box when installing the unit below -4°F, otherwise it may result in communication failure.

• Follow the instructions below to prevent abrasive components contained in sandpaper and cutting tools from entering the refrigerant circuit because those components can cause failures of the compressor and valves.

  • To deburr pipes, use a reamer or other deburring tools, not sandpaper.
  • To cut pipes, use a pipe cutter, not a grinder or other tools that use abrasive materials.
  • When cutting or deburring pipes, do not allow cutting chips or other foreign matters to enter the pipes.
  • If cutting chips or other foreign matters enter pipes, wipe them off the inside of the pipes.

Selecting a location for installation

• The branch box is only for indoor use. Please attach the special optional cover to install the branch box in the outdoors.
• Ensure that the branch box is installed above the ceiling of corridor, bath room, etc., where persons are not regularly there. Do not install near bed rooms, living rooms, etc. The sound of refrigerant flowing through the piping may sometimes be audible. Also, do not install where maintenance cannot be carried out.
• Ensure that it is located where noise in operation will not be a problem. After power is supplied or after an operation stop for a while, a small clicking noise may be heard from the inside of the branch box. The linear expansion valve is opening and closing. The unit is not faulty.
• Ensure that the branch box is installed in a location which facilitates servicing and maintenance. (ensure that the required maintenance hole or service space is available).
• Determine the route of refrigerant piping, and electrical wiring beforehand.
• Ensure that the location of the installation is such that the length of refrigerant piping is within the specified limits.
• Do not install in location that is hot or humid for long periods of time.
• Ensure that the unit is installed in a location able to support its weight.

Warning:
Ensure that the unit is installed firmly in a location able to support its weight. If the installation is of insufficient strength the unit may fall, resulting in in-jury.

Confirming supplied accessories

Check the Branch Box accessories and parts

Dimensions and required servicing space of Branch Box

Optional different-diameter (deformed) joints

• PAC-MKA53BC (5-branches type) Please connect 2 indoor units or more with 1 system.

  • Up to 2 branch boxes may be connected to 1 outdoor unit.

  • Suspension bolt : W3/8 (M10)

  • Refrigerant pipe flared connection

  • The piping connection size differs according to the type and capacity of indoor units. Match the piping connection size for indoor unit and branch box. If the piping connection size of branch box does not match the piping connection size of indoor unit, use optional different-diameter (de-formed) joints to the branch box side. (Connect deformed joint directly to the branch box side.)
    Caution:

  • Be sure to use the insulation of specified thickness. Excessive thickness may cause incorrect installation of the indoor unit and branch box, and lack of thickness may cause dew drippage.

  • 2-branch pipe (Joint) : Optional parts (According to the connection method, you can choose the favorite one.)

• Installation procedure (2 branch pipe (Joint))
  Refer to the installation manuals of MSDD-50AR-E and MSDD-50BR-E.

  • Suspension bolt pitch
  • To indoor unit
  • To outdoor unit
  • Service panel
  • Electric cover
  • Conduit plate
  • Terminal block (to indoor unit on Controller board) H Terminal block (to outdoor unit)
  • Terminal block (for comunication cable)

• PAC-MKA53BC (Fig. 4-3)

  • Suspension bolt: W3/8 (M10)
  • Refrigerant pipe flared connection

• PAC-MKA33BC (3-branches type)

• PAC-MKA33BC (Fig. 4-4)

  • Suspension bolt: W3/8 (M10)
  • Refrigerant pipe flared connection

• The direction of the piping can be changed (Fig. 4-5)

Piping direction change work procedures (Fig. 4-6 1~8)

Space required for installation and servicing

1. The space when installing with the suspension bolts.

   • (1) Front View (Fig. 4-7)

   • A Branch box

   • B On the side of piping

   • (2) Side View (Fig. 4-8, Fig. 4-9)

   • C For indoor installations

   • D Ceiling board

   • E Maintenance hole
     *1: Minimum 13-3/4 in (350 mm) is required for 90° bends in refrigerant piping

   • A: is “ Min. 7-7/8 in (200 mm)” .
     In the case of less than 7-7/8 in (200 mm) (for example A is 4 in (100 mm)), the exchange work of Branch box from a maintenance hole becomes difficult (Only exchange work of a PCB, linear expansion valve coils and sensors are possible).

   • B: is “ 23 – 5/8 in (600 mm)” .
     In the case of “ 17-3/4 in (450 mm)”, prepare a maintenance hole at a PCB side (as it is shown in Fig. 4-9), and “Min. 11-13/16 in (300 mm)” is needed as A distance .
     In the case of less than 11-13/16 in (300 mm) (for example A is 4 in (100 mm)), the exchange work of Branch box, linear expansion valve coils and sensors from a maintenance hole becomes difficult (Only exchange work of a PCB is possible).
     

   • (3) Top View (Fig. 4-10)

   • The space when installing on the floor. (Fig. 4-11)

   • The space when installing on a wall. (Fig. 4-12)

   • Warning: The installation direction is limited when installing on a wall. (Fig. 4-13)

Refrigerant piping
Always follow the specifications written in the installation manual of the outdoor unit. Exceeding these requirements may cause reduced performance of the equipment, and malfunctions.

Mounting the Branch Box

1. Install the suspension bolts (procure locally) at the specified pitch (Fig. 4-3, 4-4).
2. Fit the washers (1, 2) and nuts (procure locally) to the suspension bolts. (Fig. 6-1)
3. Hang the unit on the suspension bolts.
4. Fully tighten the nuts (check ceiling height).
5. Use a level to adjust the branch box to the horizontal.
   • A When unit is hung and nuts tightened
   • B Suspension bolt
   • C Nut (procure locally)
   • D Washer (with cushion) 1
   • E Ensure that cushion faces downwards
   • F Washer (without cushion) 2
   • G Nut (procure locally)
   • H Ceiling board

Installing refrigerant piping

Flare cutting dimensions

• Connect the liquid and gas pipes of each indoor unit to the same end connection numbers as indicated on the indoor unit flare connection section of each Branch Box. If connected to wrong end connection numbers, it doesn’t work normally.

• When connecting indoor units, make sure to connect refrigerant pipes and connection wires to the appropriate connection ports marked with matching alphabets. (Ex. A, B, C, D, E) If connected to wrong end connection numbers, it doesn’t work normally.
  Note: Be sure to mark all the local refrigerant piping (liquid pipes, gas pipes, etc.) for each indoor unit designating clearly which room it belongs in. (Ex. A, B, C, D, E)

• List indoor unit model names in the name plate of Branch Box (for identification purposes).

Piping connection procedure

1. Remove the flared nuts and caps from the branch box.

2. Flare the end of the liquid and gas pipes as shown in Fig. 7-1.

3. Apply refrigerant oil on the flared seat. (Fig. 7-2) Use the flare nut removed from the branch box. Use of an off-the-shelf nut may lead to a crack in the nut. For connection, first align the center, then tighten the first 3 to 4 turns of flare nut by hand.

4. Connect the refrigerant piping immediately. Always tighten the flared nuts to the torque specified in the Table 2 using a torque wrench and double spanner.
   Caution:

   • Tighten the flare nut with a torque wrench in the specified method. Overtightening will cause the flare nut to crack and it will cause refrigerant leakage over a period of time.
   • Follow the instructions below to prevent abrasive components contained in sandpaper and cutting tools from entering the refrigerant circuit because those components can cause failures of the compressor and valves.
   • To deburr pipes, use a reamer or other deburring tools, not sandpaper.
   • To cut pipes, use a pipe cutter, not a grinder or other tools that use abrasive materials.
   • When cutting or deburring pipes, do not allow cutting chips or other foreign matters to enter the pipes.
   • If cutting chips or other foreign matters enter pipes, wipe them off the inside of the pipes.

5. Press the pipe covers 3 and 5 on the liquid piping against the unit and wrap to hold in place. (Fig. 7-3)

6. Press the pipe covers 4 and 6 on the gas piping against the unit and wrap to hold in place. (Fig. 7-3)

7. Apply the supplied bands 9 at a position 7/16-13/16 in (10 – 20 mm) from each end of the pipe covers (3456).

8. If the indoor unit is not connected, fit the supplied pipe covers (with caps, 7 and 8) to the branch box refrigerant piping connections against the unit to prevent condensation dripping from the pipes. (Fig. 7-4)

9. Clamp the pipe covers (78) in place with the supplied bands 9.
   Note:
   A special flare nut (optional or attached to the indoor unit) is needed to some indoor units.
   Please refer to the installation manual of outdoor unit and indoor unit for details.

   • F Band (3.1. Accessories No. 9)
   • G Pipe covers (3.1. Accessories No. 3456)
   • H Thermal insulation for refrigerant piping
   • J Refrigerant piping

Handling of ports that are not connected to outdoor unit (Fig. 7-4)

1. In order to prevent refrigerant leaks, make sure that the flare nuts are tightened according to the specified torques in Table 3. Refrigerant may also leak if the flare nuts are tightened more than the specified torques.

2. In order to prevent condensation, install the pipe covers 7 8 against the unit and fasten them with the supplied bands 9.
   Refrigerant charge:
   Refer to the installation manual of the outdoor unit.
   Use only R410A refrigerant (use of other refrigerants may cause troubles).
   Caution:
   To avoid excessive strain on the branch box, support the piping with one or more support(s) 1.5 m [5 ft] or less from the branch box. Refer to Fig. 7-5 as an example.

   • J Refrigerant piping
   • L Thermal insulation for refrigerant piping

Electrical work

Precautions

• Warning:
  • Always use dedicated circuits with breakers, and at the rated voltage. Power supply circuits with insufficient capacity, and bad workmanship during installation, may result in electric shock or fire.
  • Never splice the cable, otherwise it may result in smoke, fire, or communication failure.
• Caution:
  • Be sure to establish an earth. Do not earth the unit to a utility pipe, arrester, or telephone earth. Incomplete earth may cause electrical shock. A high surge current from lightning or other sources may cause damage to the air conditioner.
  • Use the specified electrical wiring and ensure that it is connected properly, and that it is not under tension. Failure to follow these requirements may result in broken wiring, heating, or fire.
  • Never connect the main power source to the terminal block of the transmission line. If connected, electrical parts will be burnt out.
  • Wiring for control (hereinafter referred to as transmission line) shall be (5 cm or more) apart from power source wiring so that it is not influenced by electric noise from power source wiring. (Do not insert the transmission line and the power source wire in the same conduit.)
  • Be sure to set the switches before turning on the breakers of the Branch Box and the outdoor unit.
  • When power is separately supplied to the branch box and the outdoor unit, turn on the branch box first.
  • Wiring connecting branch box and outdoor unit, and branch box and indoor units, functions as both power supply and signal cable. Connect this wiring in accordance with the terminal block numbers to ensure correct polarity.

Electrical work procedure

• Connect refrigerant pipes and electrical wiring to the appropriate ports marked with matching alphabets (Ex. A, B, C, D, E) on this unit. Incorrect wiring will interfere with the correct operation of the unit.
• First, connect the power supply cable from the outdoor unit.
• Always fix each ground wire separately with a ground screw.
• To prevent that wiring installed in the ceiling is chewed by rats etc., it should be installed in wiring conduit.
  1. Remove the electric cover. (Fig. 8-1)
  2. Remove the conduit cover.
  3. Pass the wiring into the branch box through the conduit plate and fix with the conduit plate. (Refer to 8.3.)
  4. Firmly connect each wire to the appropriate terminal block. (Fig. 8-9)
  5. Set dip sw. (Refer to 8.5.)
  6. Replace the electric cover.

When using wiring conduit (Fig. 8-5, 8-6, 8-7)
Replace the electric cover when the wiring conduit has been fixed in place.

• A Electric cover
• B Wiring
• C Nut 1/2” (procure locally)
• D Wiring conduit (For TB3A, TB3B)
• E Wiring conduit (For TB3C, TB3D)
• F Wiring conduit (For TB3E)
• G Wiring conduit (For TB2B)
• H Wiring conduit (For TB5B)
• J Conduit plate (3.1. Accessories No. 0)
• K Conduit hole
• L Conduit pipe
• M Controller board
• N 2-branch wiring conduit (procure locally)(procure locally)

Caution:

• When installing the conduit plate J, cut out only the knockout holes that are necessary for wiring B. Cutting out unnecessary knockout holes may cause damage due to the invasion of small creatures and the like.
  When cutting out the knockout holes on the conduit plate, beware that neither deformation nor distortion occurs on the plate. Also, when installing the conduit plate, beware that no gap exists between the plate and the conduit pipes or the conduit holes, otherwise it may cause failure of the controller board due to the invasion of small creatures or insects. (Fig. 8-6)

• To divide the wirings of each terminal block into 2 branches outside the branch box, use 2-branch wiring conduits N. (Fig. 8-7)

Caution:
To avoid excessive strain on the branch box, support the conduit pipe L with one or more support(s) 1.5 m [5 ft] or less from the branch box. Refer to Fig. 8-8 as an example.

External wiring procedure (Fig. 8-9)

• Supply power separately to branch box and outdoor unit
• Power supply from Outdoor unit
• Refer to be installation manual of the outdoor unit

Note:

1. Wiring size must comply with the applicable local and national code.
2. Power supply cords and indoor unit/branch box/outdoor unit connecting cords shall not be lighter than polychloroprene sheathed flexible cord. (Design 60245 IEC 57)
3. Use copper supply wires.
4. Install an earth line longer than the power cables.
5. Connect the wiring in accordance with the terminal block names to ensure correct polarity.
6. Indoor unit and branch box connecting wires(C) have polarities. Make sure to match the terminal number (S1, S2, S3) for correct wirings. As for lines (C), S1 and S2 are for connecting the power source. S2 and S3 are for signals. S2 is a common cable for the power source and signal.
7. When using twisted wire for the wiring, the use of a round terminal is required. Take care when using strand wires, because fraying wires may cause the wiring to short out.
8. Do not bundle the M-NET cable with the connection cable and power supply cable. It may cause erroneous operation.
9. Recommended connection methods:
   When connecting one indoor unit to the branch box, connect it to TB3A. When connecting 2 indoor units, connect them to TB3A and TB3B. When connecting 3 indoor units, connect them to TB3A, TB3B, and TB3C. Connect indoor units in the order of A→B→C→D→E.

Power supply wiring (Supply power separately to branch box and outdoor unit)

• A switch with at least 3 mm, 1/8 inch contact separation in each pole shall be provided by the air conditioner installation. [Fig. 8-10]
  • A Ground-fault interrupter
  • B Local switch/Wiring breaker
  • C Branch Box
  • D Pull box

Warning:
Never splice the cable, otherwise it may result in a smoke, a fire or communication failure.

Warning:
In case of A-control wiring, there is high voltage potential on the S3 terminal caused by electrical circuit design that has no electrical insulation between power line and communication signal line. Therefore, please turn off the main power supply when servicing. And do not touch the S1, S2, S3 terminals when the power is energized. If an isolator should be used, use the 2 pole type between the outdoor unit and the branch box, and use the 3 pole type between the branch box and the indoor unit.

Caution:
After using the isolator, be sure to turn off and on the main power supply to reset the system. Otherwise, the outdoor unit may not be able to detect the branch box(es) or indoor units.

Switch setting

Dip switch setting (Shut off the outdoor unit and branch box power supply before setting)

Address switch SW11, SW12 (Shut off the outdoor unit and branch box power supply before setting) Actual indoor unit address setting varies in different systems. Refer to the installation manual for the outdoor unit for details on how to make the address setting. Each address is set with a combination of the settings for the tens digit and ones digit.
[Factory default value] Set to “1”.

• (Example)
  • When setting the address to “3”, SW12 (tens digit) “0”, SW11 (ones digit) “3”
  • When setting the address to “25”, SW12 (tens digit) “2”, SW11 (ones digit) “5”
• (Example)
  • • When setting the address of the branch box to “3”, an address is assigned to each indoor unit starting with Unit A as shown below no matter if each indoor unit is connected.
  • (SW1-1~5 ON)
    • Indoor Unit A Address 3
    • Indoor Unit B Address 4
    • Indoor Unit C Address 5
    • Indoor Unit D Address 6
    • Indoor Unit E Address 7
  • When the address is set to “25” and also 3 indoor units (Unit A, Unit C, and Unit E) are connected. (SW1-1, 1-3, 1-5 ON)
  • Indoor Unit A Address 25
  • Indoor Unit C Address 26
  • Indoor Unit E Address 27

Test run

• Refer to the “Test run” section of the installation manual of the indoor units and outdoor unit.

• When the branch box and outdoor power source are separate, turn on the power of the branch box first, and then turn on the outdoor unit power.

• After power is supplied or after an operation stop for a while, a small clicking noise may be heard from the inside of the branch box. The linear expansion valve is opening and closing. The unit is not faulty.

• Be sure to perform the test run in cooling mode for each indoor unit. Make sure each indoor unit operates properly following the installation manual attached to the unit.

• If you perform the test run for all indoor units at once, you cannot detect any erroneous connection, if any, of the refrigerant pipes and the indoor/outdoor unit connecting wires.

• To check for improper wiring, perform the test run for each indoor unit individually.
  Caution:

  • Use the remote controller to operate the indoor unit.
  • The following symptoms are not malfunctions.

Saeffe the operation manual of indoor units for details.
This mode is activated for approximately 1 minute to help avoid an insufficient supply of refrigerant during heating operation when refrigerant is stored in an indoor unit that has been turned off or thermo-off.

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