Installation Manual (View Online) – KHTA / KBTA / KRTA / KCTA Series (R32): Ducted Indoor ARTH24KHTA, ARTH30KHTA, ARTH36KHTA, ARTH45KHTA, ARTH54KHTA, ARTH60KHTA + Outdoor AOTH30KBTA, AOTH36KBTA, AOTH45KBTA, AOTH54KBTA, AOTH60KBTA, AOTH36KRTA, AOTH45KRTA, AOTH54KRTA, AOTH60KRTA, AOTH45KCTA, AOTH54KCTA, AOTH60KCTA + UTY-RNRT Wired Controller

Applies to:
Indoor (Ducted): ARTH24KHTA / ARTH30KHTA / ARTH36KHTA / ARTH45KHTA / ARTH54KHTA / ARTH60KHTA
Outdoor (Single type): AOTH30KBTA / AOTH36KBTA / AOTH45KBTA / AOTH54KBTA / AOTH60KBTA
Outdoor (Single type): AOTH36KRTA / AOTH45KRTA / AOTH54KRTA / AOTH60KRTA
Outdoor (Single type): AOTH45KCTA / AOTH54KCTA / AOTH60KCTA
Wall Controller (Wired): UTY-RNRT
Refrigerant: R32
Audience: Authorised service personnel / professional installers

Contents

1) Safety and compliance

  • Installation and servicing must be completed by qualified and experienced personnel only.
  • Do not energise the system until all installation work is complete and covers are fitted.
  • After isolating power, wait before touching electrical components (observe manufacturer discharge guidance).
  • If refrigerant leakage occurs during works: ventilate immediately and remove ignition sources.
  • Use vacuum pump evacuation (do not purge with refrigerant).
  • Ensure correct grounding/earthing and earth leakage protection as required by local regulations.

2) R32 refrigerant requirements

  • R32 operates at higher pressures than legacy systems; only use R32/R410A-rated tools, hoses and materials.
  • Charging port thread for R32/R410A: 1/2–20 UNF.
  • Prevent moisture/foreign matter entering piping; seal pipe ends during storage/handling.
  • Leak detection must be suitable for flammable refrigerants; do not use open flame methods.
  • Comply with relevant safety standards and local regulations for flammable refrigerants.

3) Tools and materials (R32/R410A rated)

  • High-pressure gauge manifold suitable for R32/R410A
  • R32/R410A charging hoses
  • Vacuum pump and appropriate adapters (as required)
  • R32/R410A compatible leak detector
  • Tube cutter, deburr tool, flare tool suitable for R32/R410A, torque wrenches for flare nuts and caps
  • Nitrogen cylinder + regulator for pressure testing

4) System overview (power, control, commissioning flow)

  • Recommended workflow: Install (mechanical) → electrical → pressure test → evacuation → open service valves → add charge (if required) → function settings (static pressure) → test run → handover.
  • Confirm wiring terminal numbering matches on both ends and cable routing avoids contact with refrigerant piping and sharp edges.
  • Where a wired controller is used (UTY-RNRT), ensure addressing / control configuration aligns to the job scope before commissioning.

5) Refrigerant piping requirements

5.1 Copper pipe material and minimum wall thickness (R32/R410A)

  • Use seamless phosphor deoxidised copper.
  • Do not use existing piping (risk of contamination and incompatibility).

Minimum wall thickness (annealed copper) by pipe outside diameter:

  • 6.35 mm outside diameter (nominal size 1/4"): minimum thickness 0.80 mm
  • 9.52 mm outside diameter (nominal size 3/8"): minimum thickness 0.80 mm
  • 12.70 mm outside diameter (nominal size 1/2"): minimum thickness 0.80 mm
  • 15.88 mm outside diameter (nominal size 5/8"): minimum thickness 1.00 mm
  • 19.05 mm outside diameter (nominal size 3/4"): minimum thickness 1.20 mm

5.2 Line sizes (single type – standard outdoor reference)

  • Typical pipe diameter (Liquid / Gas): 9.52 mm (3/8") / 15.88 mm (5/8")
  • Always insulate both liquid and gas lines. Increase insulation thickness in high humidity environments.
  • Protect pipe ends against moisture/dust entry during storage and installation.

5.3 System piping limits (outdoor unit reference)

  • Minimum piping length: 5 m
  • Maximum height difference (Indoor → Outdoor): 30 m
  • Maximum piping length by outdoor model family:
    • AOTH30KBTA / AOTH36KBTA / AOTH45KBTA / AOTH54KBTA / AOTH36KRTA / AOTH45KRTA / AOTH54KRTA: 50 m
    • AOTH60KBTA / AOTH60KRTA: 50 m
    • AOTH45KCTA / AOTH54KCTA / AOTH60KCTA: 75 m

6) Electrical requirements

6.1 Outdoor unit power supply (AOTH30KBTA, AOTH36KBTA, AOTH45KBTA, AOTH54KBTA, AOTH60KBTA, AOTH36KRTA, AOTH45KRTA, AOTH54KRTA, AOTH60KRTA, AOTH45KCTA, AOTH54KCTA, AOTH60KCTA)

  • Voltage rating: 1Φ 220–240 V (50 Hz) / 3Φ 380–415 V (50 Hz)
  • Operating range: 1Φ 198–264 V / 3Φ 342–457 V
  • Power supply cable (minimum):
    • Single phase: Minimum 4 mm² (Type 60245 IEC 66), 2 cable + Earth (Ground)
    • Three phase: Minimum 2.5 mm² (Type 60245 IEC 57), 4 cable + Earth (Ground)

Breaker capacity / Earth leakage breaker (reference) by outdoor model grouping:

  • AOTH30KBTA / AOTH36KBTA (Single phase): Breaker capacity 25 A; Earth leakage breaker 30 mA
  • AOTH45KBTA / AOTH54KBTA (Single phase): Breaker capacity 32 A; Earth leakage breaker 30 mA
  • AOTH36KRTA / AOTH45KRTA / AOTH54KRTA (Three phase): Breaker capacity 16 A; Earth leakage breaker 30 mA
  • AOTH45KBTA / AOTH54KBTA / AOTH60KBTA (Single phase): Breaker capacity 32 A; Earth leakage breaker 30 mA
  • AOTH60KRTA (Three phase): Breaker capacity 16 A; Earth leakage breaker 30 mA
  • Install a disconnect device with a contact gap of at least 3 mm in all poles nearby the units (indoor and outdoor) as required by local regulations.

6.2 Indoor to outdoor connection cable

  • Refer to the indoor unit installation manual for connection cable specifications and terminal assignments.
  • Limit voltage drop to less than 2%; increase conductor size if required.
  • Do not connect AC supply to transmission terminals.

7) Outdoor unit installation (AOTH30KBTA, AOTH36KBTA, AOTH45KBTA, AOTH54KBTA, AOTH60KBTA, AOTH36KRTA, AOTH45KRTA, AOTH54KRTA, AOTH60KRTA, AOTH45KCTA, AOTH54KCTA, AOTH60KCTA)

7.1 Location and mounting

  • Install on a base that can withstand weight and vibration; use anchor bolts and appropriate anti-vibration measures.
  • Maintain required clearances for airflow and service access (including discharge air recirculation control).
  • Do not install where combustible gas may accumulate or in corrosive environments.
  • Secure appropriately for local wind/weather conditions.

7.2 Drain considerations (outdoor)

  • Heating operation produces drain water; route to a suitable drain point where applicable.
  • In freezing climates, apply appropriate freeze protection strategies per local best practice.

8) Indoor unit installation (ARTH24KHTA, ARTH30KHTA, ARTH36KHTA, ARTH45KHTA, ARTH54KHTA, ARTH60KHTA)

8.1 Site selection and serviceability

  • Install in a location that supports the unit mass and minimises vibration transmission.
  • Ensure ducting, filter access, and condensate drain access are serviceable after installation.
  • Ensure appropriate access for electrical service and refrigerant piping connections.

8.2 Ductwork and airflow management (critical)

  • Confirm ductwork design external static pressure (ESP) aligns with unit capability.
  • Seal duct joints to prevent air leakage and performance degradation.
  • Confirm return air path and filter arrangement prevents debris ingress to the fan/coil.

8.3 Condensate drain

  • Provide correct fall and trapping per local best practice to prevent blow-off and odours.
  • Insulate condensate line where sweating may occur.
  • Water-test drainage prior to ceiling closure / handover.

9) Pressure test, evacuation, commissioning

9.1 Flare work – tightening torques (system)

Flare nut tightening torque by pipe size:

  • 1/4" pipe size (outside diameter 6.35 mm): 16–18 N·m
  • 3/8" pipe size (outside diameter 9.52 mm): 32–42 N·m
  • 1/2" pipe size (outside diameter 12.70 mm): 49–61 N·m
  • 5/8" pipe size (outside diameter 15.88 mm): 63–75 N·m
  • 3/4" pipe size (outside diameter 19.05 mm): 90–110 N·m

9.2 Leak test (air tightness test)

  • Perform an air tightness test using nitrogen while all outdoor unit valves are closed.
  • Use the test pressure indicated on the outdoor unit nameplate and confirm all joints are leak-free prior to evacuation.

9.3 Vacuum evacuation

  • Evacuate to –0.1 MPa (–76 cmHg).
  • When –0.1 MPa is reached, operate the vacuum pump for at least 60 minutes.
  • After evacuation, disconnect hoses, then open service valves fully and refit caps to specified torques.

9.4 Service valve / port cap torques (outdoor reference)

Service valve / port cap tightening torques:

  • Blank cap (applicable sizes 1/4", 3/8"): 20–25 N·m
  • Blank cap (applicable size 1/2"): 28–32 N·m
  • Blank cap (applicable size 5/8"): 30–35 N·m
  • Blank cap (applicable size 3/4"): 35–40 N·m
  • Charging port cap (R32/R410A): 12.5–16 N·m

10) Additional refrigerant charging (AOTH30KBTA, AOTH36KBTA, AOTH45KBTA, AOTH54KBTA, AOTH60KBTA, AOTH36KRTA, AOTH45KRTA, AOTH54KRTA, AOTH60KRTA, AOTH45KCTA, AOTH54KCTA, AOTH60KCTA)

  • Pre-charge length: 30 m
  • If piping length exceeds 30 m, additional refrigerant is required.
  • Charging guideline: 40 g per metre beyond 30 m.
  • Record factory charge, additional charge, and total charge on the outdoor unit refrigerant label.

10.1 Additional charge guidance for KBTA and KRTA outdoor models

Applies to: AOTH30KBTA / AOTH36KBTA / AOTH45KBTA / AOTH54KBTA / AOTH60KBTA / AOTH36KRTA / AOTH45KRTA / AOTH54KRTA / AOTH60KRTA

  • Piping length 30 m or less: No additional refrigerant required
  • Piping length 40 m: Add +400 g (40 g/m beyond 30 m)
  • Piping length 50 m: Add +800 g (40 g/m beyond 30 m)
  • Guideline: 40 g per metre beyond 30 m

10.2 Additional charge guidance for KCTA outdoor models

Applies to: AOTH45KCTA / AOTH54KCTA / AOTH60KCTA

  • Piping length 30 m or less: No additional refrigerant required
  • Piping length 40 m: Add +400 g (40 g/m beyond 30 m)
  • Piping length 50 m: Add +800 g (40 g/m beyond 30 m)
  • Piping length 60 m: Add +1200 g (40 g/m beyond 30 m)
  • Piping length 70 m: Add +1600 g (40 g/m beyond 30 m)
  • Piping length 75 m: Add +1800 g (40 g/m beyond 30 m)
  • Guideline: 40 g per metre beyond 30 m

10.3 Maximum total charge (per outdoor model reference)

  • AOTH30KBTA / AOTH36KBTA: 2700 g (1900 g + 800 g)
  • AOTH45KBTA / AOTH54KBTA: 3500 g (2700 g + 800 g)
  • AOTH60KBTA / AOTH60KRTA: 4200 g (with a piping length of 50 m)
  • AOTH45KCTA: 5200 g (with a piping length of 75 m)
  • AOTH54KCTA / AOTH60KCTA: 5600 g (with a piping length of 75 m)

11) Indoor function settings (ARTH – static pressure / airflow)

  • Purpose: Align indoor fan operation to the duct system’s design external static pressure (ESP).
  • Factory setting reference: 100 Pa.
  • Complete ducting and filters before setting ESP. Incomplete ductwork will produce incorrect airflow outcomes.
  • Function settings are performed via the installed controller / service procedure (wired remote controller environment).

11.1 Static pressure setting (Function No. 26) – ARTH24KHTA / ARTH30KHTA / ARTH36KHTA

Static pressure setting options for Function No. 26 (ARTH24KHTA, ARTH30KHTA, ARTH36KHTA):

  • Function No. 26, Setting value 06: Static pressure 60 Pa
  • Function No. 26, Setting value 07: Static pressure 70 Pa
  • Function No. 26, Setting value 08: Static pressure 80 Pa
  • Function No. 26, Setting value 09: Static pressure 90 Pa
  • Function No. 26, Setting value 10: Static pressure 100 Pa
  • Function No. 26, Setting value 11: Static pressure 110 Pa
  • Function No. 26, Setting value 12: Static pressure 120 Pa
  • Function No. 26, Setting value 13: Static pressure 130 Pa
  • Function No. 26, Setting value 14: Static pressure 140 Pa
  • Function No. 26, Setting value 15: Static pressure 150 Pa
  • Function No. 26, Setting value 16: Static pressure 160 Pa
  • Function No. 26, Setting value 17: Static pressure 170 Pa
  • Function No. 26, Setting value 18: Static pressure 180 Pa
  • Function No. 26, Setting value 19: Static pressure 190 Pa
  • Function No. 26, Setting value 20: Static pressure 200 Pa
  • Function No. 26, Setting value 21: Static pressure 210 Pa
  • Function No. 26, Setting value 31: Static pressure Standard (60 Pa)
  • Function No. 26, Setting value 32: Static pressure Automatic airflow adjustment

11.2 Static pressure setting (Function No. 26) – ARTH45KHTA / ARTH54KHTA / ARTH60KHTA

Static pressure setting options for Function No. 26 (ARTH45KHTA, ARTH54KHTA, ARTH60KHTA):

  • Function No. 26, Setting value 06: Static pressure 60 Pa
  • Function No. 26, Setting value 07: Static pressure 70 Pa
  • Function No. 26, Setting value 08: Static pressure 80 Pa
  • Function No. 26, Setting value 09: Static pressure 90 Pa
  • Function No. 26, Setting value 10: Static pressure 100 Pa
  • Function No. 26, Setting value 11: Static pressure 110 Pa
  • Function No. 26, Setting value 12: Static pressure 120 Pa
  • Function No. 26, Setting value 13: Static pressure 130 Pa
  • Function No. 26, Setting value 14: Static pressure 140 Pa
  • Function No. 26, Setting value 15: Static pressure 150 Pa
  • Function No. 26, Setting value 16: Static pressure 160 Pa
  • Function No. 26, Setting value 17: Static pressure 170 Pa
  • Function No. 26, Setting value 18: Static pressure 180 Pa
  • Function No. 26, Setting value 19: Static pressure 190 Pa
  • Function No. 26, Setting value 20: Static pressure 200 Pa
  • Function No. 26, Setting value 21: Static pressure 210 Pa
  • Function No. 26, Setting value 22: Static pressure 220 Pa
  • Function No. 26, Setting value 23: Static pressure 230 Pa
  • Function No. 26, Setting value 24: Static pressure 240 Pa
  • Function No. 26, Setting value 25: Static pressure 250 Pa
  • Function No. 26, Setting value 26: Static pressure 260 Pa
  • Function No. 26, Setting value 31: Static pressure Standard (60 Pa)
  • Function No. 26, Setting value 32: Static pressure Automatic airflow adjustment

11.3 Operational guidance (field practical)

  • Manual setting: Select the required Pa value when duct design ESP is known.
  • Automatic airflow adjustment: Use when commissioning requires automated fan calibration (ensure system is complete and stable before initiation).
  • After changing settings, validate airflow, noise profile, and temperature performance outcomes under normal load conditions.

12) Test run and handover

12.1 Check items

  • Controller operation and display status normal
  • Indoor fan operation stable (no hunting / abnormal ramping)
  • Airflow achieved and duct system balanced
  • Drainage normal (no water leakage)
  • No abnormal noise or vibration
  • No refrigerant leakage detected

12.2 Customer guidance

  • Explain controller operation, setpoints, timers/schedules (where applicable).
  • Explain filter access/cleaning intervals and service requirements.
  • Confirm any building management interface / external interlocks (if installed).

13) Pump down (forced cooling operation)

  • Use pump down for relocation/disposal refrigerant recovery in accordance with the manufacturer procedure and local regulatory requirements.
  • Initiate forced cooling/test run mode per controller guidance (method varies by controller type).
  • Close the 2-way valve fully, then close the 3-way valve after the required run period, then stop operation.
  • Do not proceed if refrigerant is depleted due to damaged piping; confirm leak-free condition first.

14) Error codes (indoor/outdoor consolidated)

Error codes may be displayed on the wired controller, or indicated via indoor LED blink patterns where applicable. Capture the code, confirm wiring/communication integrity, and follow standard diagnostic workflow.

14.1 Error code list (one-line format)

  • 11 – Serial communication error
  • 12 – Wired remote controller communication error
  • 15 – Check run unfinished / automatic airflow adjustment error
  • 16 – Peripheral unit transmission PCB connection error
  • 18 – External communication error
  • 21 – Unit number / address setting error (system dependent)
  • 22 – Indoor unit capacity error
  • 23 – Combination error
  • 24 – Connection unit number error (system dependent)
  • 26 – Indoor unit address setting error
  • 27 – Primary/secondary unit setup error (system dependent)
  • 29 – Connection unit number error in wired remote controller system
  • 31 – Power supply interruption error
  • 32 – Indoor unit PCB model information error
  • 33 – Indoor unit motor electricity consumption detection error
  • 35 – Manual auto switch error
  • 39 – Indoor unit power supply error for fan motor
  • 3A – Indoor unit communication circuit (wired remote controller) error
  • 41 – Room temperature sensor error
  • 42 – Indoor unit heat exchanger middle temperature sensor error
  • 44 – Occupancy sensor error
  • 51 – Indoor unit fan motor error
  • 53 – Drain pump error
  • 57 – Damper error
  • 59 – Indoor unit fan motor 2 error
  • 5U – Indoor unit error
  • 61 – Outdoor unit reverse/missing phase and wiring error
  • 62 – Outdoor unit main PCB model information error / communication error
  • 63 – Inverter error
  • 64 – Active filter error / PFC circuit error
  • 65 – Trip terminal / IPM temperature error
  • 68 – Rush current limiting resistor temperature rise error
  • 6A – Display PCB microcomputer communication error
  • 71 – Discharge temperature sensor error
  • 72 – Compressor temperature sensor error
  • 73 – Outdoor heat exchanger liquid temperature sensor error
  • 74 – Outdoor temperature sensor error
  • 75 – Suction gas temperature sensor error
  • 76 – 2-way / 3-way valve temperature sensor error
  • 77 – Heat sink temperature sensor error
  • 82 – Sub-cool heat exchanger sensor error
  • 83 – Liquid pipe temperature sensor error
  • 84 – Current sensor error
  • 86 – Pressure sensor / high pressure switch error
  • 94 – Trip detection
  • 95 – Compressor rotor position detection error (permanent stop)
  • 97 – Outdoor unit fan motor 1 error
  • 98 – Outdoor unit fan motor 2 error
  • 99 – 4-way valve error
  • 9A – Expansion valve (coil) error
  • A1 – Discharge temperature error
  • A3 – Compressor temperature error
  • A4 – High pressure error
  • A5 – Low pressure error
  • AC – Heat sink temperature error
  • J2 – Branch boxes error (system dependent)

15) UTY-RNRT specific error displays

These error displays are specific to UTY-RNRT wired remote controller system conditions (in addition to the consolidated system error code list above).

15.1 UTY-RNRT error display list (one-line format)

  • CC.1 – Sensor error (wired remote controller side)
  • C2.1 – Transmission PCB error
  • 12.1 – Wired remote controller communication error
  • 12.3 – Communication circuit error (wired remote controller)
  • 12.4 – Indoor unit communication circuit error (wired remote controller)
  • 26.4 – Wired remote controller unit number or refrigerant circuit address setting error
  • 26.5 – Indoor unit address setting error
  • 15.4 – Data acquisition error

Document control: This Solution article is intended as a consolidated, text-only field reference for KHTA/KBTA/KRTA/KCTA ducted installation and commissioning. Always comply with local regulations and manufacturer requirements for detailed diagrams, part numbers, and regional variations.