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Inspect the unit for damage and verify specifications before installation.
Guidance on positioning and securing the fan coil unit for installation.
Instructions for installing the unit in an upflow configuration.
Instructions for converting and installing the unit in a downflow configuration.
Procedures for installing the unit in horizontal orientations.
Steps for converting units to a horizontal right orientation.
Connecting supply and return air ducts to the fan coil unit.
Recommendations for acoustical treatment of ductwork.
Guidelines for making electrical connections to the unit.
Connecting the main power supply to the unit.
Wiring the low-voltage control system for thermostat and accessories.
Details on the unit's transformer for voltage conversion.
Requirements for multi-stage heating room thermostats.
Specific electrical wiring requirements for manufactured housing.
Ensuring proper grounding for electrical safety.
Selecting appropriate fan speeds for optimal airflow and performance.
Details on how to select motor speed taps.
Connecting refrigerant lines and evacuating the system.
Information on the TXV and its installation or servicing.
Procedures for disassembling and reassembling the TXV.
Proper installation of condensate drain lines and traps.
Information on installing optional accessories like humidifiers.
Connecting the humidifier and humidistat to the fan coil unit.
Explanation of how the unit operates in different modes.
Operation sequence for the continuous fan mode.
Operation sequence for the cooling mode.
Operation sequence for heat pump heating with auxiliary electric heat.
Operation sequence for electric heat or emergency heat modes.
Steps to follow for initial system start-up.
This document provides installation instructions for PF4MNX series fan coil units, covering models from 018 to 060. These units are designed for installation flexibility and are compliant with low leak requirements, featuring a cabinet leakage rate of less than 2% at 0.5 inches W.C. and 1.4% at 0.5 inches W.C. when tested according to ASHRAE 193 standard.
The PF4MNX fan coil units are designed to work with R-410A refrigerant air conditioners and heat pumps, providing heating and cooling for residential and manufactured housing applications. They utilize a multi-tap ECM motor for efficiency, allowing for various airflow performance settings. The units are available for systems ranging from 18,000 to 60,000 BTUh nominal cooling capacity.
The fan coil units can be configured for upflow, downflow (requiring a kit), and horizontal orientations. For heating, they can be equipped with factory-installed or field-installed UL listed heater packages. The control system includes a 24V low-voltage circuit, protected by a 3A automotive-type fuse, with motor speeds and time delay functions built into the motor itself, eliminating the need for a separate circuit board.
Refrigerant flow is controlled by a mechanical TXV (Thermostatic Expansion Valve) designed for R-410A refrigerant. Condensate drainage is managed through primary and secondary 3/4" FPT drain connections, which require proper trapping to ensure optimal performance and prevent water overflow.
Installation Flexibility: The units can be installed in upflow, downflow, or horizontal configurations. For downflow applications, an accessory downflow kit and base kit are required, along with specific procedures for converting the condensate drains. Horizontal installations are factory-built for horizontal left, but can be converted to horizontal right with specific modifications to the coil assembly and drain pan. When suspending units from the ceiling, dimples in the casing indicate suitable locations for mounting metal support straps.
Air Duct Connections: Supply-air ducts connect to 3/4" (19 mm) flanges on the supply-air opening. Flexible connectors are recommended between ductwork and the unit to prevent vibration. For units with electric heaters, heat-resistant material must be used for flexible connectors at the discharge connection. Ductwork in unconditioned spaces must be insulated and covered with a vapor barrier. Specific clearances to combustible materials are required for electric heaters, depending on their kW rating.
Electrical Connections: Low-voltage wiring uses #18 AWG color-coded, insulated wire (35°C minimum) for connections between the thermostat, unit, and outdoor equipment. For distances over 100 feet (30 m), #16 AWG wire is required. All wiring must comply with NEC Class 1 and be separated from incoming power leads. The transformer is factory-wired for 230V operation but can be reconfigured for 208V applications.
Motor Speed Selection: Fan speed selection is done at the motor connector, with various speed taps (Tap 1 to Tap 5) offering different CFM and off-delay settings. Taps 1, 2, and 3 have a 90-second blower off time delay, while Tap 4 (electric heat only) and Tap 5 (high static applications) have a 0-second delay. The unit wiring label specifies the minimum fan speed required.
Refrigerant Tubing: Units have sweat suction and liquid tube connections. Brazing connections require silver-bearing or non-silver-bearing materials, avoiding solder that melts below 800°F (427°C). The coil and tubing system must be evacuated to 500 microns before opening outdoor unit service valves. A brazing shield must be used to prevent damage to the unit surface and condensate pan fitting caps.
Condensate Drains: Primary and secondary drain lines must be installed with properly-sized P-traps (minimum 2 inches / 51 mm deep) to ensure optimum drainage and prevent property damage. Shallow running traps are inadequate. The drain lines should be pitched downward at a minimum slope of 1" (25 mm) for every 10' (3 m) of length. PVC fittings are recommended for plastic condensate pans.
Humidifier Connection: The units support connection of a humidifier and humidistat, with specific wiring layouts provided for units with or without electric heat. A cooling lockout relay is optional.
Periodic Maintenance: To ensure high performance and minimize equipment failure, periodic maintenance is essential. This typically involves filter replacement or cleaning on a monthly basis. For more complex maintenance, consulting a qualified dealer is recommended.
Filter Access: The unit should never be operated without a filter. Factory-authorized filter kits can be used for internal filter placement. If internal access is impractical, a field-supplied filter must be installed in the return air duct system.
Blower Assembly Service: Servicing the blower assembly requires the removal of two screws connecting the blower housing to the fan deck. These screws do not need to be reinstalled after service.
Condensate Drain Maintenance: Condensate drain lines should be regularly checked for blockages. Traps should be primed, and the system tested for leaks. Insulation around traps located above living areas is important to prevent condensation.
Safety Precautions: The manual emphasizes the importance of following all safety codes, wearing protective clothing, and having a fire extinguisher available. It highlights warnings regarding personal injury, property damage, electrical shock, and cut hazards. Before servicing, all power to the unit must be turned off, and refrigerant charge must be removed from the system when servicing the TXV. The cabinet must have an uninterrupted ground to minimize personal injury in case of an electrical fault.
General| Model | PF4MNX |
|---|---|
| Refrigerant | R-410A |
| Seasonal Energy Efficiency Ratio (SEER) | Up to 16 |
| Cabinet Material | Galvanized Steel |
| Type | Air Handler |
| Airflow | Up to 2000 CFM |
| Dimensions | Varies by model size |
| Voltage | 208/230V |
| Motor Type | ECM |
| Filter Type | Standard |
| Height | Varies by model |
| Width | Varies by model |
| Depth | Varies by model |
