Installing a Lennox heat pump or configuring a low ambient control kit requires meticulous attention to detail and adherence to safety protocols. The process involves several key steps, including outdoor placement, electrical connections, refrigerant handling, and the use of specialized components such as relays, pressure switches, and freezestats. These instructions are derived from official installation and service documentation provided by Lennox, ensuring a reliable and safe setup for both cooling and heating operations.
This article provides a comprehensive guide to the installation of Lennox heat pumps and the 68M04 Low Ambient Control Kit. It outlines the necessary precautions, tools, and procedures to ensure a proper and compliant installation. The instructions are intended for licensed professionals or qualified service agencies and are not suitable for general DIY installation due to the complexity and safety risks involved.
Safety Precautions and General Guidelines
Before beginning the installation process, it is essential to review and follow all safety guidelines provided by the manufacturer. Improper installation, adjustment, or maintenance can result in serious injury or equipment damage. The following warnings are emphasized in the provided documentation:
- Electrical Shock Hazard: Ensure the unit is grounded in accordance with national and local codes. Disconnect all remote electric power supplies before opening the access panel. Units may have multiple power supplies.
- Physical Injury Risk: Be cautious when working near metal edges or corners, especially during installation or servicing.
- Refrigerant Handling: Always wear appropriate personal protective equipment when handling refrigerants. Follow proper evacuation and charging procedures to prevent refrigerant loss and ensure system efficiency.
Installation must be performed by a licensed professional or certified service agency. This ensures that all safety and performance standards are met, particularly for systems involving high-voltage connections and refrigerant handling.
Outdoor Placement Considerations
The location of the heat pump significantly impacts its performance and noise levels. The following considerations should be taken into account when determining the outdoor placement:
- Distance from Property Lines: Be mindful of local sound ordinances, which may restrict the unit’s proximity to neighboring properties based on decibel levels. Install the unit as far away as possible from property lines.
- Avoid Windows: Install the unit away from windows, as glass can transmit sound more effectively, potentially disturbing occupants.
- Ground-Level Installations: When placing the unit on a slab, ensure the top of the slab is sufficiently elevated to prevent water accumulation from higher ground.
- Roof Mounting: If the unit is mounted on a roof, maintain a minimum clearance of 6 inches above the roof surface to prevent ice buildup.
These guidelines help ensure optimal performance and compliance with local regulations.
Installation of the 68M04 Low Ambient Control Kit
The 68M04 Low Ambient Control Kit is a critical component for maintaining system performance in cold weather conditions. The kit includes a low ambient pressure switch, relays (K58 and K159), and other necessary wiring and hardware. The installation process involves the following steps:
- Power Disconnection: Turn off the electrical power to the unit to prevent accidental energization during installation.
- Access Panel Removal: If applicable, remove the compressor compartment access panel to gain access to the liquid line service port.
- Pressure Switch Installation:
- Install the low ambient pressure switch on the tee fitting before attaching it to the liquid line service port to avoid refrigerant loss.
- Use a torque wrench to tighten the seal cap on the tee valve core port to 6 to 8 ft.-lbs. If a torque wrench is unavailable, finger-tighten and use an appropriately sized wrench to turn an additional 1/6 turn clockwise.
- Wiring: Route the pressure switch wires to the control box and connect them according to the applicable unit wiring diagram.
- Relay Installation: Depending on the model, either K58 or K159 relay will be used. Install the relay in the designated location as shown in the provided diagrams.
Freezestat Installation
The freezestat (S49) is an optional but important component for systems operating in low-temperature environments. It must be ordered separately and installed according to the following guidelines:
- Installation Location: Mount the freezestat on one of the copper lines between the last hairpins and the suction manifold of the indoor coil.
- Functionality: The freezestat senses line temperature and cycles the compressor off when the temperature drops below its setpoint. It operates at non-adjustable set points listed in the manufacturer’s specifications.
Electrical Connections and Thermostat Setup
Electrical wiring must comply with local and national codes. The following steps outline the necessary procedures:
- Circuit Sizing and Disconnect Switch Installation: Consult the unit’s data plate to determine the minimum circuit ampacity and the maximum fuse or circuit breaker rating. Install the power wiring and a properly sized disconnect switch.
- Thermostat Installation: A separately ordered thermostat must be installed inside the home. Position it on an interior wall, approximately in the center of the conditioned area, and 5 feet above the floor.
- Low Voltage Connections: Run the 24VAC control wires through the cutout with a grommet. Secure the wires using a wire tie to ensure a stable connection.
- High Voltage Connections: Route high voltage wiring through conduit and connect it according to the manufacturer’s specifications. Ensure all high voltage connections are properly grounded.
Refrigerant Handling and Leak Testing
After installation, it is crucial to verify the integrity of the refrigerant system. The following steps should be followed:
- Refrigerant Charging:
- Connect the HFC-410A refrigerant cylinder to the center port of the manifold gauge set.
- Open the refrigerant cylinder and follow the charging procedure outlined in the manufacturer’s documentation.
- Polyol Ester Oil Addition:
- Add oil based on the amount of refrigerant charge in the system.
- Systems with 20 pounds or less refrigerant do not require additional oil.
- Systems with more than 20 pounds of HFC-410A refrigerant should have one ounce of oil added for every five pounds of refrigerant.
- Leak Detection:
- Use a leak detection method such as electronic detectors or soap bubbles to identify any refrigerant leaks.
- Repair any identified leaks before proceeding with system testing.
Operation in Cooling and Heating Modes
Understanding how the system operates in both cooling and heating modes is essential for troubleshooting and maintenance. The following outlines the operational sequences:
Cooling Mode:
- The defrost control receives a Y and O signal from the room thermostat.
- The O signal energizes the reversing valve and the K58 relay coil, opening contact K58-1.
- The Y signal passes through the freezestat to Y1 on the defrost control.
- The signal travels through the defrost control to the HI-PS terminals, out to the high pressure switch and discharge thermostat, and back to the other HI-PS terminal.
- The signal returns from the defrost control on the Y terminal, energizing the compressor contactor coil.
- The outdoor fan motor remains off until the liquid line pressure reaches 450 psig (3100 kPa).
- Once this pressure is reached, the low ambient pressure switch closes, energizing the K159 relay coil.
- K159-1 contacts close, and the outdoor fan motor cycles on.
- The outdoor fan will cycle off when the liquid line pressure drops below 240 psig (1600 kPa).
Heating Mode:
- The defrost control receives a Y signal from the room thermostat.
- The O signal is not energized, so the K58 relay coil remains de-energized, and contact K58-1 remains closed.
- The Y signal passes through the defrost control to the HI-PS terminals, out to the high pressure switch and discharge thermostat, and back to the other HI-PS terminal.
- The signal returns from the defrost control on the Y terminal, energizing the compressor contactor coil.
- The outdoor fan motor remains off until the liquid line pressure reaches 450 psig (3100 kPa).
- The low ambient pressure switch then energizes the K159 relay coil, closing K159-1 contacts and cycling the outdoor fan motor on.
Braze and Line Set Installation
Proper installation of the refrigerant lines is essential for system efficiency and longevity. The following steps should be followed:
- Cutting and Deburring:
- Square cut the ends of the refrigerant lines and deburr the cut ends.
- Avoid crimping the ends to maintain roundness.
- Brazing Connections:
- Remove the service cap and core from both the liquid line service valve and suction/vapor line service valve ports.
- Use proper brazing techniques and materials to ensure a secure and leak-free connection.
- Horizontal and Vertical Runs:
- For horizontal runs, use metal strapping or heavy nylon wire ties to hang the line sets from joists or rafters.
- For vertical runs, insulate the liquid lines if the ambient temperature is higher than the liquid line temperature or if the pressure drop is equal to or greater than 20 psig.
Recovery and Recycling of Refrigerant
Before removing or replacing any components, it is necessary to recover and recycle the refrigerant to comply with environmental regulations. The following steps outline the process:
- Recovery Setup:
- Connect the recovery machine to the system using the appropriate manifold and gauge set.
- Ensure all system valves are closed.
- Recovery Procedure:
- Open the recovery machine and allow it to pull the refrigerant until the system pressure reaches 0.
- Close the inverted HCFC-22 drum’s valve and the gauge set valves.
- Pump out any remaining refrigerant and turn off the recovery machine.
- Recycling:
- Follow the manufacturer’s guidelines for recycling refrigerant in accordance with local and federal regulations.
Conclusion
The installation of a Lennox heat pump and the 68M04 Low Ambient Control Kit involves a series of complex and interdependent steps. Each procedure must be performed with precision and care to ensure the system operates efficiently and safely. The guidelines outlined in this article are based on official installation and service documentation from Lennox, ensuring compliance with safety standards and best practices.
Proper outdoor placement, electrical connections, refrigerant handling, and component installation are all critical to the system's performance. Additionally, understanding the operational sequences in both cooling and heating modes is essential for troubleshooting and maintenance. By following the detailed instructions provided, licensed professionals can ensure a successful and compliant installation.