This document outlines the installation, operation, and maintenance procedures for the Trane ODYSSEY Light Commercial Split System, specifically the TTA Model 50 Hz air-cooled condensing units, ranging from 5 to 20 tons. The manual covers single-circuit models (TTA075, TTA100, TTA120), dual-circuit models (TTA150, TTA180, TTA200, TTA240), and manifolded compressor models (TTA150RD0G, TTA180RD0G, TTA200RD0G, TTA240RD0G).
Function Description
The Trane ODYSSEY split system is designed for cooling-only applications in light commercial settings. It consists of an outdoor air-cooled condensing unit and an indoor evaporating unit (blower), which work together to provide conditioned air. The system utilizes R-22 refrigerant and is controlled by a room thermostat.
Cooling Mode:
When the system switch on the room thermostat is set to COOL and the fan switch to AUTO, the compressor contactor energizes, initiating the operation of the compressor and condenser fan. Simultaneously, the evaporator fan contactor energizes, starting the evaporator fan. For dual-circuit units, a second stage of cooling, if required, is activated by the Y2 signal from the indoor thermostat, energizing the second compressor.
Evaporator Fan Operation:
The evaporator fan can be controlled by an ON/AUTO switch on the room thermostat. In AUTO mode, the fan operates concurrently with the cooling cycles. When the fan switch is set to ON, the evaporator fan runs continuously, irrespective of the cooling operation.
Safety Controls:
The unit incorporates several safety controls to ensure proper and safe operation:
- Low Pressure Cut-Out (LPCO): Located in the suction line, this control stops the compressor and outdoor fans if suction pressure drops below a preset limit, preventing damage from low refrigerant levels.
- High Pressure Cut-Out (HPCO): Positioned in the liquid line, this device shuts off the compressor and outdoor fans if the discharge pressure exceeds its design limit, protecting against excessive head pressure.
- Internal Overload Protector (IOL): This current/thermal actuated warp switch is embedded in the compressor motor windings. It shuts off the compressor if the motor's temperature or current exceeds its design trip temperature. The compressor will restart once the motor cools down, but a check of the refrigerant and electrical systems is recommended to identify and correct the underlying cause.
Usage Features
The ODYSSEY unit is designed for straightforward installation and operation, with clear guidelines for refrigerant piping and electrical connections.
Installation:
- Lifting and Mounting: The unit should be lifted using appropriate equipment and spreader bars to prevent damage. For ground-level installations, the unit base must be adequately supported and level, extending two inches beyond the unit base channels. Isolation from adjacent structures is recommended to prevent noise or vibration issues.
- Clearances: Specific minimum clearances are required around the unit for unrestricted access to service points and proper air circulation. Condenser discharge clearance should be at least 2.5 mm, and condenser intake air is supplied from three sides of the unit.
- Refrigerant Piping: Detailed guidelines are provided for selecting tube lengths and sizes, pitching horizontal suction lines for oil drainage, and avoiding large oil traps. The manual specifies recommended line sizes for single, dual, and manifolded compressor circuits, along with maximum allowable pressure drops. All refrigerant piping and connections must be insulated.
- Refrigerant Piping Procedures: The installation involves removing the R-22 holding charge, brazing tubing connections using a dry nitrogen purge, and then leak-checking the entire system with dry nitrogen.
- System Evacuation and Charging: After leak checking, the system must be evacuated to a 350-micron vacuum. Refrigerant charging is performed by weighing the R-22 cylinder and introducing the correct amount of refrigerant, or by gaseous charging while the unit is operating, monitoring suction and head pressures. The manual provides recommended refrigerant charge amounts for various models and additional refrigerant requirements based on tubing length.
- Electrical Wiring: Field wiring involves providing power supply to the unit and installing the indoor thermostat. All wiring must comply with local and national codes, and copper conductors are required. A disconnect switch must be installed in a convenient location.
Operation:
Once properly installed and pre-start procedures are complete, the unit is started by setting the System Switch on the indoor thermostat to either COOL or AUTO. The system should then operate normally. It is crucial to ensure the indoor air handler disconnect is closed before operating the outdoor unit to prevent trip-outs or liquid flood-back to the compressors.
Maintenance Features
Regular maintenance is crucial for prolonging the unit's life and ensuring efficient, reliable operation. The manual outlines monthly and annual maintenance procedures.
Monthly Maintenance:
- Safety First: Always open and lock the unit disconnect to prevent electrical shock or contact with moving parts before attempting any maintenance.
- Air Filters: Inspect and clean air filters as necessary.
- Wiring: Check all wiring connections for tightness and ensure insulation is intact.
- Drain Pans and Piping: Verify that drain pans and condensate piping are free of obstructions.
- Outdoor Fan: Manually rotate the outdoor fan to ensure proper operation and inspect mounting hardware for tightness.
- Coils: Inspect evaporator and condenser coils for dirt and debris; clean if necessary.
- Pressures: With the unit operating in cooling mode, check and record suction and discharge pressures, comparing them to the values provided in the "Pressure Curves" (not included in this excerpt).
- Indoor Fan: Observe indoor fan operation for unusual or excessive vibration; clean blower wheels as needed.
Annually (Cooling Season) Maintenance:
These procedures should be performed at the beginning of each cooling season in addition to the monthly checks:
- All Monthly Inspections: Perform all the monthly maintenance tasks.
- Superheat: With the unit operating, check and record the superheat reading.
- Casing Cleaning: Remove any accumulation of dust and/or dirt from the unit casing.
- Corrosion: Remove corrosion from any surface and repaint as needed.
- Control Panel Gasket: Check the gasket around the control panel door for proper fit and condition to prevent water leakage.
- Evaporator Fan Belt: Inspect the evaporator fan belt; replace if worn or frayed.
- Control Panel Wiring: Inspect control panel wiring for tight connections and intact insulation.
- Indoor Fan Motor Lubrication: Lubricate indoor fan motor bearings with non-detergent, 20-weight oil every six months (note: some motors are permanently lubricated).
- Refrigerant Piping: Check refrigerant piping and fittings for leaks.
The manual also includes a "Maintenance Log" table to record ambient temperature, evaporator entering air (dry and wet bulb), compressor suction and discharge pressures, superheat, and subcooling for each circuit. This log helps track performance and identify potential issues over time.
Troubleshooting:
A troubleshooting chart is provided to assist in diagnosing common issues related to the refrigerant circuit (e.g., head pressure, suction pressure, liquid overfeeding, coil frosting) and electrical system (e.g., compressor/fan not starting, compressor cycling on internal overload). The chart indicates primary and secondary causes for each problem.
Maintenance Contract and Training:
Trane strongly recommends signing a maintenance contract with a local Service Agency for regular maintenance by specialists. This ensures timely detection and correction of malfunctions, minimizes serious damage, and prolongs equipment life. Additionally, Trane offers a refrigeration and air conditioning service school to provide operators and technicians with knowledge for optimal equipment use, maintenance, and prevention of costly breakdowns.
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