Aspen A2L Refrigerant Multi-Position Air Handlers

Content Overview

• Important Safety Instructions
• Introduction & General Information
• Inspection
• General Information and Installation Preparation
• Installation Instructions and Clearances
• Installation
• Connecting Refrigerant Lines
• Metering Devices / Liquid Line Connection
• Leak Check / Standing Pressure Test / Vacuum Test
• Electrical Line Voltage Wiring
• Low Voltage Connections
• Air Volume Adjustment
• System Charging
• Hydronic Heat
• A2L Refrigerant Leak Detection Systems
• Final System Checkout
• Wiring Diagrams

Safety First

This manual emphasizes safety. Potential hazards are indicated by symbols and specific warnings. Always read and comply with all safety information and instructions before operating, installing, or servicing the unit. Key safety points include:

• Disconnect all power before servicing or installing.
• Do not bypass safety devices.
• Use caution with flammable refrigerants; ensure proper ventilation and no ignition sources.
• Only certified technicians should perform installation and service.
• Follow all national and local building codes and electrical codes.
• Ensure proper ventilation, especially in enclosed spaces.
• Do not puncture refrigerant tubing. Dispose of refrigerant properly.
• Use only factory-authorized parts and accessories.
• California Proposition 65 warning: This product may expose you to chemicals, including lead, known to the State of California to cause cancer and birth defects or other reproductive harm. Visit www.65Warnings.ca.gov for more information.

General Information

Aspen's A2L refrigerant air handlers (AAM, AEM, LAM, LEM series) are versatile, multi-positional units designed for upflow, downflow, horizontal left, and horizontal right applications. They are compatible with R32 or R454B refrigerants and can be AHRI matched with most brands of air conditioners or heat pumps.

Key features include:

• Motors: Constant torque ECM motors for AEM/AAL models, PSC motors for AAM models.
• Cabinet: Sturdy, insulated steel cabinet with stick pins for insulation.
• Blower: Direct drive, multi-speed blowers for quiet and efficient operation.
• Coils: High-efficiency rifled aluminum tubes and enhanced aluminum fins for maximum heat transfer. Coils are factory leak-tested.
• Metering Devices: Available with flowrator/fixed orifice piston or TXV.
• Drain Pan: Rugged GLP drain pan with primary and secondary drain connections.
• A2L Refrigerant Leak Detection System: Standard on units designed for A2L refrigerants, including an A2L Sensor, Mitigation Control Board, and wiring harnesses.
• Warranty: Ten-year limited parts warranty.

The unit is designed for operation with 208/240 V, single-phase, 60 Hz power supply. Aspen is not responsible for damages caused by modification for alternative power sources. The appliance is not intended for use at altitudes exceeding 2,000 meters.

Installation Preparation

Before installation, read all instructions carefully and gather necessary tools. Ensure the unit is properly sized and that the outdoor unit's tonnage does not exceed the air handler's tonnage.

Ductwork: Duct systems must comply with National Fire Protection Association standards (NFPA 90A or 90B) and be sized according to National Environmental System Contractors Association Manual K. Use non-flammable flexible collars for return and discharge connections to prevent vibration transmission. Insulate ductwork passing through unconditioned areas.

Condensate Drain: Ensure proper drainage with a minimum 2” trap installed in the condensate drain line. An auxiliary drain pan is recommended for added protection. Drain lines must be installed with a 1/4” per foot pitch.

Refrigerant Lines: Follow manufacturer recommendations for refrigerant line sizes. Ensure all connection joints are clean and free of burrs. Protect Schrader valves and sensing bulbs from heat during brazing.

Installation Procedures

Mounting: If installed in areas prone to physical damage, install adequate protective barriers. Mount the unit at least 18” away from ignition sources.

Orientation: The unit can be installed in upflow, counterflow, horizontal right, or horizontal left discharge configurations. Follow specific instructions for converting between orientations.

Connecting Refrigerant Lines: Release nitrogen holding charge before installation. Braze refrigerant line connections using proper procedures. Seal penetration openings where line-sets enter the cabinet.

Metering Devices: Follow specific instructions for flowrator/fixed orifice piston or TXV installation based on the refrigerant type and outdoor unit manufacturer's recommendations. Ensure correct piston or TXV sizing and proper installation of the sensing bulb for TXV systems.

Leak Check & Vacuum Test: Pressurize the field piping and indoor coil with dry nitrogen or dry helium to the specified pressure and check for leaks using a soapy solution. Evacuate the system until the micron gauge reads no higher than 350 microns and holds vacuum.

Electrical Wiring: Disconnect all power before servicing. Ensure compliance with National Electric Code and local codes. Use appropriate wire sizing and connections, especially for aluminum wiring. Wire selection and wiring must be in accordance with the latest edition of the National Electric Code.

Low Voltage Connections: A 24V power supply is provided by an internally wired low voltage transformer. Ensure the line voltage tap is correctly set for the supplied voltage (208V or 240V).

Air Volume Adjustment

Set air volume to the level recommended by the outdoor unit manufacturer, typically around 400 CFM per ton of cooling capacity. Use a Magnehelic Gauge to measure static pressure and adjust speed taps accordingly. Ensure the factory-provided air filter is installed.

System Charging

Units designed for R32 refrigerant must be charged with R32, and units for R454B must be charged with R454B. Ensure the corresponding sensor is installed and operational. Follow outdoor unit manufacturer's charging guidelines. For TXV systems, adjust refrigerant to achieve specified subcooling or superheat values. For fixed orifice/piston systems, add refrigerant until the measured superheat matches the chart values.

Electric Heat Kits

Air handlers are available with factory or field-installed electric heater kits (3kW to 20kW). Refer to product specification sheets and installation manuals for compatible kits. Not intended for simultaneous operation of electric heat and reverse cycle heating.

A2L Refrigerant Leak Detection Systems

Units designed for A2L refrigerants are equipped with a refrigerant leak detection system (RDS). The system includes an A2L Sensor, Mitigation Control Board, and Accessory Control Relay. The Mitigation Control Board monitors the A2L Sensor for refrigerant leaks and activates mitigation measures (e.g., compressor lockout, fan operation) if a leak is detected. Ensure the sensor is properly installed and powered. Follow the manual's instructions for system testing and verification.

Final System Checkout

Ensure all cabinet openings are sealed, check for condensate leakage, perform refrigerant leak detection, and secure all cabinet doors. Verify that all gaskets are intact for airtight application.

Wiring Diagrams

Detailed wiring diagrams are provided for single-stage and multi-stage AC and heat pump systems, including PSC and ECM motor configurations. Refer to these diagrams for proper electrical connections.