Inside an AAON R&D Cabinet Unit: A Comprehensive Guide to Components and Operation

For HVAC professionals and building managers working with AAON equipment, understanding the layout and operation of an R&D cabinet unit is crucial. This guide will walk you through the key components and operational aspects of a typical 50-ton AAON unit, breaking down the refrigeration cycle and explaining important features like the Hot Gas Reheat system.

Cabinet Layout and Basic Components

When you first open an AAON R&D cabinet, you'll notice a systematic layout designed for efficient operation and maintenance:

1. High Voltage Section: Located on one side of the cabinet
2. Low Voltage Controls: Adjacent to the high voltage section
3. Refrigeration Components: Positioned below the electrical sections
4. Heating System: Found below the fan on the unit's side (on D cabinets)

Understanding the Refrigeration Cycle

Dual Circuit Design

The unit employs a dual circuit, four-compressor configuration - a typical arrangement for AAON makeup air units. Let's break down the key components and their operation:

1. Compressor Operation

• Suction Gas Intake:
  • Location: Bottom of each compressor
  • Typical Readings (on an 80-85°F day):
    • Pressure: Approximately 125 PSI
    • Temperature: Around 42°F

2. Compression Process

The compressors transform the refrigerant from a low-pressure gas to a high-pressure, high-temperature gas:

• Discharge Temperature: 110-120°F
• Discharge Pressure: Approximately 375 PSIG

3. Hot Gas Reheat System

A standout feature of AAON units, particularly in makeup air units designed for dehumidification, is the modulating Hot Gas Reheat valve system:

• Discharge Gas Path:
  1. Exits compressor
  2. Travels behind control panels
  3. Enters a three-way valve
• Three-Way Valve Function:
  • Incoming gas temperature: Approximately 102°F
  • Splits flow between:
    1. Circuit A: Directs to condenser coil (top of unit)
    2. Circuit B: Routes to modulating Hot Gas Reheat coil (inside cabinet)

Why This Matters for Building Operations

Understanding these components and their operation is crucial for:

1. Proper maintenance scheduling
2. Efficient troubleshooting
3. Optimal performance tuning
4. Energy efficiency optimization

Maintenance Tips

When working with AAON R&D cabinet units:

1. Regularly check suction and discharge pressures
2. Monitor discharge temperatures
3. Ensure proper operation of the Hot Gas Reheat valve
4. Keep electrical sections clean and connections tight

Finding Replacement Parts

For maintenance or repairs, it's crucial to use genuine OEM parts. Common components that may need replacement:

• Compressors
• Three-way valves
• Control boards
• Sensors

At OEM HVAC Parts, we stock a full range of AAON components to keep your unit running at peak efficiency.

Need Assistance?

Whether you're troubleshooting an issue or looking for replacement parts for your AAON unit, our team of HVAC experts is here to help. Contact us for:

• Technical support
• Parts identification
• Maintenance guidance
• Installation advice

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For all your AAON HVAC needs, trust the experts at OEM HVAC Parts to provide the right solutions and support.