Daikin AMST U1400 Series

This document provides installation and operating instructions for AMST*U1400 series air handlers, manufactured by Daikin Comfort Technologies Manufacturing, L.P. These air handlers are designed for indoor installation only, at altitudes between -184 feet and 10,500 feet above sea level.

Function Description:

The AMST*U1400 series air handlers are designed to be a core component of a complete supply and return ductwork system for residential and light commercial heating, ventilation, and air conditioning (HVAC) systems. They are compatible with various outdoor sections, including single-stage cooling and heat pump units, with options for single or two-stage electric heating. The units feature 9-speed energy-efficient blower motors that operate at a constant torque with low power consumption, delivering adequate airflow at rated external static pressure. They are designed to manage condensation effectively, particularly in humid environments, and can be installed in multiple orientations: upflow, downflow, horizontal left, or horizontal right.

Important Technical Specifications:

Electrical Supply: Factory-shipped for use with 208/240/1/60 electrical power supply. Reconfiguration for other power supplies is not permitted.
Voltage Range: Minimum 197 VAC, Maximum 253 VAC for 208-230 VAC nominal input.
Airflow: Designed to accommodate 350-450 CFM per ton of cooling, with static pressure not exceeding 0.5” in w.c. Airflow data tables are provided for various static pressures and speed taps (T1-T9), with adjustments for horizontal left (0.98 CFM adjustment factor) and horizontal right/downflow (0.96 CFM adjustment factor) orientations.
Leakage Rate: Achieves less than 1.4% airflow leakage when tested in accordance with ASHRAE Standard 193, provided all gaskets are intact and panels are flush.
Refrigerant: Factory-shipped with R410A and dry nitrogen mixture gas under pressure.
Drain Pan Connections: Primary and secondary drains with 3/4" NPT female connections.
Filter Compatibility: Designed for nominal 16x20x1", 20x20x1", or 24x20x1" filters (actual dimension less than 23-1/2"x20") for B, C, and D cabinet sizes. External filters may be required for specific horizontal right or downflow installations.
Heat Kit Compatibility: Only HKS and HKTSD series electric heat kits are permitted.
Low Voltage Wiring: Copper conductors, minimum 18AWG for installations up to 100 feet.

Usage Features:

Installation Flexibility: Can be installed in upflow, downflow, horizontal left, or horizontal right orientations. Specific instructions are provided for each, including removal of shipping brackets, coil assembly, and drain pan components.
Condensate Management: Features primary and secondary drain connections. A "P" style trap is required for proper drainage, and secondary drain pans are mandatory for installations above finished living spaces or in locations prone to condensate overflow.
Speed Tap Adjustment: Features 9-speed blower motors. Speed taps (T1-T9) can be adjusted by moving the Purple (PU) wire lead on the terminal block to achieve desired CFM. For AMST60DU1400** models, specific instructions are given for high and low static applications.
Humid Environment Installations: For areas with return air humidity above 65% relative humidity, a High Humidity Kit (HHK) is required. Downflow installations in humid environments also require a Downflow Kit (DFK), and horizontal installations require a Condensate Management Kit (CMK).
Ductwork: Designed for a complete supply and return ductwork system. Ductwork should be sized to ACCA Manual D, S, and RS standards, be flame retardant, and sealed to prevent leakage. Return ductwork should not be located in areas that can introduce toxic or objectionable fumes/odors.
Refrigerant Line Connections: Includes an adjustable TXV with bulb. Detailed instructions for brazing joints and ensuring proper superheat and subcooling are provided.

Maintenance Features:

Filter Replacement/Cleaning: The circulating air filter(s) should be cleaned or replaced regularly, typically once per month.
Coil Cleaning: Aluminum tube evaporator coils should be flushed with water. Corrosive chemical cleaners (e.g., containing chlorine or hydroxides) are prohibited as they can cause premature coil failure. Approved cleaning agents are listed in TP-109.
Motor Lubrication: Indoor and outdoor fan motors are permanently lubricated and do not require additional oiling.
Troubleshooting (Before Calling Servicer):
- Check thermostat settings.
- Wait 15 minutes for automatic resets.
- Check electrical panel for tripped circuit breakers or failed fuses.
- Verify the disconnect switch near the indoor furnace or blower is closed.
- Inspect the outdoor unit for obstructions.
- Check indoor air inlets and outlets for blockages.
- Inspect and clean/replace the air filter.
- Listen for unusual noises.
Safety Devices: Do not bypass safety devices.
Professional Service: All other maintenance and service procedures, including adjustments and repairs, must be performed by a certified service technician. Improper service can lead to injury, property damage, or product damage.