Lennox XC25 Series - User Manual

The Lennox XC25 System is a high-efficiency air conditioner designed for residential use, offering advanced cooling and heating capabilities. This outdoor unit is an integral component of a complete HVAC system, requiring an iComfort Wi-Fi® thermostat and an iComfort™-enabled air handler or furnace for optimal operation. The system utilizes HFC-410A refrigerant, a more environmentally friendly option, and incorporates variable capacity compressor technology for precise temperature control and energy efficiency.

Function Description

The primary function of the Lennox XC25 is to provide cooling and, when paired with a compatible indoor unit, heating for residential spaces. Its variable capacity compressor allows it to adjust its output based on demand, maintaining a consistent indoor temperature with fewer fluctuations than traditional single-stage systems. This technology contributes to improved comfort and reduced energy consumption. The unit is designed to work seamlessly with the iComfort Wi-Fi® thermostat, which provides intelligent control and monitoring of the entire HVAC system. The thermostat allows users to manage settings remotely, receive system alerts, and optimize performance through smart features.

The XC25 system's operation involves a refrigerant cycle where HFC-410A absorbs heat from the indoor air and releases it outdoors during cooling, or vice versa during heating. The variable speed compressor enables the system to operate at different capacities, from low-speed, energy-saving modes to high-speed, rapid cooling or heating. This adaptability ensures that the system can efficiently meet diverse comfort needs while minimizing operational noise.

Usage Features

Installation of the XC25 system requires careful attention to clearances and piping to ensure proper function and longevity. The unit should be installed on a level surface or a slope with a maximum tolerance of 2 degrees (2 inches per 5 feet) away from the building structure. Specific clearances are required around the unit for maintenance access and airflow, including 30 inches to the access panel, 36 inches to one side, 12 inches to two sides, and 6 inches to the final side. Minimum clearance above the unit is 48 inches. When installing multiple units, a minimum clearance of 24 inches between them is necessary.

The system's refrigerant piping is a critical aspect of installation. For new installations or when replacing an existing system, the line set must be flushed according to industry standards, especially if the previous system used mineral oil or if contaminants are present. Polyol ester (POE) oils, used with HFC-410A, absorb moisture quickly, so it's crucial to keep the refrigerant system closed until connections are ready. The manual provides detailed guidelines for line set sizing and application, considering factors like total equivalent length, linear length, liquid lift, and vapor riser length. For line sets up to 50 linear feet, standard sizes are recommended. For lengths between 51 and 150 linear feet, specific tables guide the selection of liquid and vapor line sizes, and a crankcase heater is required. Line sets over 150 linear feet are not recommended.

Brazing procedures for connecting the refrigerant lines must be performed with caution, using water-saturated cloths to protect service valve seals and flowing nitrogen through the lines to prevent oxidation. After brazing, the system must undergo a leak test and evacuation to ensure a tight, moisture-free system. This involves pressurizing the lines with a trace amount of HFC-410A and nitrogen, checking for leaks with a detector, and then evacuating the system to a deep vacuum of 500 microns or less.

Electrical wiring must conform to local codes and the National Electric Code (NEC) in the U.S.A. or the Canadian Electrical Code (CEC) in Canada. The unit requires a 24VAC transformer (40 VA minimum) for low-voltage control power. The iComfort Wi-Fi® thermostat requires four wires between the thermostat and the furnace/air handler control, and four wires between the outdoor unit and the furnace/air handler control. Any unused wires in the cable should be bundled with a wire nut and connected to the C terminal to prevent electrical noise. High voltage wiring should be trimmed and secured away from low voltage wiring.

Maintenance Features

Routine maintenance is essential for the XC25 system to ensure peak performance and longevity. Homeowners can perform some basic tasks, while others require a licensed HVAC professional.

For homeowners:

Air Filter Checks: The indoor unit's air filter should be checked monthly and cleaned or replaced as needed. Disposable filters should be replaced with the same type and size.
Outdoor Unit Clearances: Ensure no obstructions restrict airflow to the outdoor unit. Grass clippings, leaves, or shrubs should be kept trimmed away from the unit. Periodically check for debris that collects around the unit.
Snow Levels: During winter, keep snow levels below the louvered panels to ensure proper performance.
Sprinkler Systems: Sprinklers and soaker hoses should not be installed where they could cause prolonged exposure to the outdoor unit by treated water, as this can corrode steel and aluminum parts, diminishing performance and longevity.

For HVAC professionals:

Coil Cleaning: The outdoor unit's coil should be cleaned by a licensed professional technician. It is recommended to schedule inspections and service at least once a year, or twice a year for optimal performance.
Drain Pan and Line Checks: The indoor evaporator coil's drain pan and line should be checked for obstructions.
System Refrigerant Charge: The refrigerant charge should be checked and adjusted using the tables provided on the unit access panel and in the XC25 Installation and Service Procedures manual.
Alarm Monitoring: The outdoor control's seven-segment display and the iComfort Wi-Fi® thermostat provide alarm information, which can help diagnose system issues. Detailed alarm information is available in the XC25 Installation and Service Procedures manual.

Before any service or maintenance, the electrical power to the unit must be turned OFF at the disconnect switch. It's important to wait at least 5 minutes after power removal, as electrical components may hold a charge. Electrostatic discharge (ESD) precautions should be followed to protect the unit's electronic controls during service.

Lennox XC25 Series Specifications

General

Compressor Type	Variable Speed
Cooling Capacity	Up to 5 tons
Sound Rating	As low as 59 dB
Energy Star Certified	Yes
Refrigerant	R-410A
Stages of Cooling	Variable
SEER Rating	26
Warranty	10-Year Limited Warranty on covered components