Ascend™ Air-Cooled Chiller ACS: Annual Maintenance

Maintenance

! WARNING

Hazardous Voltage - Pressurized Flammable Fluid!

Failure to follow all electrical safety precautions could result in death or serious injury. Do not operate compressor without terminal box cover in place.

The motors in the compressors have strong permanent magnet motors and have the capability to generate voltage during situations when the refrigerant charge is being migrated. This potential will be present at the motor terminals and at the output of the variable speed drives in the power panel.

Before removing compressor terminal box cover for servicing, or servicing power side of control panel, CLOSE COMPRESSOR DISCHARGE SERVICE VALVE and disconnect all electric power including remote disconnects. Discharge all motor start/run capacitors. Follow lockout/tagout procedures to ensure the power cannot be inadvertently energized. Verify with an appropriate voltmeter that all capacitors have discharged.

The compressor contains hot, pressurized refrigerant. Motor terminals act as a seal against this refrigerant. Care should be taken when servicing NOT to damage or loosen motor terminals.

! WARNING

Pressurized Burning Fluid!

Failure to follow the instructions below could result in death or serious injury. Do not operate compressor without terminal box cover in place.

The compressor contains hot, pressurized refrigerant. Motor terminals act as a seal against this refrigerant. Care should be taken when servicing NOT to damage or loosen motor terminals.

! WARNING

Hazardous Voltage w/Capacitors!

Failure to follow these instructions could result in death or serious injury.

Disconnect all electric power, including remote disconnects and discharge all motor start/run and AFD (Adaptive Frequency™ Drive) capacitors before servicing. Follow proper lockout/tagout procedures to ensure the power cannot be inadvertently energized.

For variable frequency drives or other energy storing components provided by Trane or others, refer to the appropriate manufacturer’s literature for allowable waiting periods for discharge of capacitors. Verify with an appropriate voltmeter that all capacitors have discharged.

DC bus capacitors retain hazardous voltages after input power has been disconnected. Follow proper lockout/tagout procedures to ensure the power cannot be inadvertently energized. After disconnecting input power, wait five (5) minutes for the DC capacitors to discharge, then check the voltage with a voltmeter. Make sure DC bus capacitors are discharged (0 VDC) before touching any internal components.

This section describes the basic chiller preventive maintenance procedures, and recommends the intervals at which these procedures should be performed. Use of a periodic maintenance program is important to ensure the best possible performance and efficiency.

Use an Operator Log (see Log and Check Sheet chapter) to record an operating history for unit. The log serves as a valuable diagnostic tool for service personnel. By observing trends in operating conditions, an operator can anticipate and prevent problem situations before they occur. If unit does not operate properly during inspections, see Diagnostics chapter.

Recommended Maintenance

Annual

NOTICE:

Coil Damage! Use of detergents could cause damage to coils. Do not use detergents to clean coils. Use clean water only.

Refrigerant and Oil Charge Management

Proper oil and refrigerant charge is essential for proper unit operation, unit performance, and environmental protection. Only trained and licensed service personnel should service the chiller.

The following table lists baseline measurements for chillers running at AHRI standard operating conditions. If chiller measurements vary significantly from values listed below, problems may exist with refrigerant and oil charge levels. Contact your local Trane office.

Note: Low temperature applications units will have values that vary from the following table. Contact your local Trane office for more information.

Table 28. Typical baselines (AHRI conditions)

Lubrication System

Oil Level

Oil should also be visible in the sight glass when the compressor is running. When operating, each compressor in a tandem or trio set may have a different oil level.

To check compressor oil level, refer to the label near the compressor sight glass. The compressor(s) must be off. Wait three minutes. With tandem or triple compressors the oil level will equalize after shutdown. Compressor oil level should be clearly visible within the sight glass when the compressors are off

Important: If oil level is low, contact your local Trane office. Verify that ONLY Trane OIL00080 is used.

Oil Testing

NOTICE:

Compressor Damage!

POE oil is hygroscopic – it absorbs water directly from the air. This water is nearly impossible to remove from the compressor oil and can result in compressor failures.

To prevent POE oil from absorbing water, the system should not remain open for longer than necessary. When open, dry nitrogen should flow through the piping. Only new oil containers should be used for service and maintenance. Always use the smallest container size required for the job requirements. Always leave the oil container tightly sealed until time of use. Do not reuse oil that has been opened.

Important: In the event of a compressor failure, always test the oil with an acid test kit to determine whether the compressor failure was mechanical or electrical. This information is required to determine the correct cleanup procedure.

Condenser Maintenance

Condenser Coil Cleaning

For information regarding the proper microchannel coil cleaning procedure, refer to RF-SVG001*-EN.

Coil Cleaning Interval

Cleaning Air Side of Coils

NOTICE:

COIL DAMAGE! Use of coil cleaning agents on uncoated coils could cause damage to coils. Do not use coil cleaning agents to uncoated clean coils. Use clean water only.

Do not use detergents to clean the air side of coils. Use clean water only. Clean from inside out by removing end panels

Cleaning Coated Coils

! WARNING

Hazardous Chemicals!

Coil cleaning agents can be either acidic or highly alkaline and can burn severely if contact with skin or eyes occurs.

Handle chemical carefully and avoid contact with skin. ALWAYS wear Personal Protective Equipment (PPE) including goggles or face shield, chemical resistant gloves, boots, apron or suit as required. For personal safety refer to the cleaning agent manufacturer’s Materials Safety Data Sheet and follow all recommended safe handling practices.

Coated coils may be cleaned using traditional detergents.

Repair/Replacement of Microchannel Coil

Microchannel coils are considerably more robust in design than tube and fin condenser coils, however they are not indestructible. When damage or a leak occurs, contact your local Trane office.

Condenser Coil Corrosion Protection Inspection

Perform coil inspection each time coils are cleaned

Inspect corrosion protection at each coil refrigerant connection where the copper tube joins the aluminum manifold. If damaged or missing, wrap new Prestite Insulated tar tape (STR01506) on joint to cover area from the aluminum header body to at least 2 inches of the copper tube. Seal insulation using hand pressure. Rubber gloves are suggested when handling insulation.

Note: Prestite insulated tar tape is required for all units at each copper/aluminum connection. This requirement is NOT associated with the coated coil option.

Evaporator Maintenance

This chiller uses a brazed plate heat exchanger (BPHE) evaporator with factory-installed electronic flow switch (IFM efector) that is positioned in the evaporator water pipe. The evaporator inlet also includes a factoryinstalled immersion heater for freeze protection and a water strainer that must be kept in place to keep debris out of the evaporator.

Note: Strainer maintenance is critical to proper operation and reliability. Any particles larger than 1mm entering the BPHE evaporator may cause the evaporator to fail, requiring replacement.

Acceptable BPHE evaporator water flow rate is 1.2 to 3.6 gpm/ton. To maintain 54-44°F in/ out chilled water temperatures, the nominal water flow rate is 2.4 GPM/ ton.

Minimum water flow rate must be maintained to avoid laminar flow, potential evaporator freezing, scaling and poor temperature control. The microprocessor and capacity control algorithms are designed to take a 10 percent change in water flow rate per minute while maintaining a ±2°F (1.1°C) leaving water temperature control accuracy. The chiller tolerates up to 30 percent per minute water flow variation as long as the flow is equal to or greater than minimum flow requirements.

Maximum water flow is 18 feet per second. Flow rates greater than this will cause excessive erosion.

The BPHE evaporator is difficult to clean should it become plugged with debris. Indications of a plugged BPHE evaporator include "wet" suction due to lack of heat exchange, loss of superheat control, depressed discharge superheat, compressor oil dilution and/or starvation and premature compressor failure.

Water Strainer Maintenance

An in-line strainer with a V-shaped sieve is used for units that do not have factory-installed pump package option.

Figure 49. In-line strainer, units without pump package

The strainer is equipped with a blow-down port. The strainer is a 16 mesh (approximately 1 mm) material.

For maximum efficiency, a differential pressure gauge installed across the inlet and outlet will indicate pressure loss due to clogging and may be used as a guide to determine when cleaning is required. The taps for the pressure gauges are included as standard from the factory.

Normally when differential pressure reaches 5-10psi, the screen must be cleaned. The strainer is equipped with a blow-down port on the cover plate. To clean open and flush out until any sediment is removed

Units with Pump Package

For units with optional pump package, the factoryinstalled water strainer is a Y-type design with a cylindrical sieve.

Figure 50. Y—type strainer, units with pump package

Pump Package Maintenance

Pumps not immediately placed into service, or removed from service and stored, must be properly prepared to prevent excessive rusting.