Name: PCB Assy (Printed Circuit Board Assembly)
Part Number: 5020991
Manufacturer: Daikin
Function:
The 5020991 PCB Assy serves as the main control unit for a variety of Daikin air-to-water heat pump systems. It manages key operational logic, communication between internal modules, and system safety monitoring.

✅ Compatible Daikin Models

This PCB is compatible with multiple models across the Daikin EHBH and EHBX series, designed for low-temperature heat pump applications:

These models are used in residential and light commercial hydronic heating and domestic hot water systems.

🔧 Key Functional Roles

• Central Control Logic:
  Interprets sensor data and manages operation of heating, pump, and domestic hot water cycles.

• System Communication:
  Interfaces with:

  • Outdoor unit inverter

  • User interface

  • Safety and flow sensors

  • Heat exchanger and circulation pump controllers

• Energy Management:
  Ensures optimized heating cycles to maintain energy efficiency and compliance with seasonal performance targets.

• Diagnostics & Alarms:
  Logs faults, triggers alarms, and communicates with service tools via Daikin’s diagnostics interface.

🛠️ Installation & Use

📦 Features:

• Durable construction with factory-installed firmware

• Designed for long-term reliability under normal HVAC operating conditions

🧰 Installation Tips:

• Ensure static-safe handling during installation

• Match cable harnesses and sensor ports exactly to avoid miswiring

• Requires system reboot and possible configuration post-installation