The provided document is an Installation, Operation, and Maintenance Manual for the Nagas Express ABE Series Energy Recovery System, designed for both indoor and outdoor installations.
Function Description
The Nagas Express ABE Series is a high-efficiency energy recovery system that utilizes heat banks to store and discharge energy between two airstreams in a cyclical manner. This system is designed for industrial or commercial use to recover energy from exhaust air and transfer it to incoming fresh air, or vice-versa, depending on the operational mode (heating or cooling recovery). The unit incorporates dampers that move in a synchronized sequence to direct airflow through the heat banks, optimizing energy transfer. A control system manages the damper positions based on different modes and modulation signals, with rapid transitions between positions.
The system's core function is to maintain a desired supply air temperature setpoint by modulating the recuperator dampers. In heating recovery mode, when the outside air temperature is lower than the supply setpoint (minus a differential) and the return air temperature is higher than the supply setpoint, the unit transfers heat from the return air to the incoming fresh air. Conversely, in cooling recovery mode, when the outside air temperature is higher than the supply setpoint (plus a differential) and the return air temperature is lower than the supply setpoint, the unit transfers coolness from the return air to the incoming fresh air. When neither recovery mode is active, the unit enters a cleaning mode, cycling the recuperator every 60 minutes.
The unit can operate in three control modes: Local Control Mode, Remote Control Mode, and BACnet Control Mode. In Local Control Mode, the unit is started via the Human Machine Interface (HMI) screen or remote display, and fans operate at a speed chosen in the HMI. In Remote Control Mode, the unit starts via a dry contact signal, and fans modulate based on a 0-10V input signal. In BACnet Control Mode, the unit is controlled via BACnet communication (MSTP or IP) for starting, setting supply temperature, and fan airflow.
Important Technical Specifications
- Clearances to Combustible Material:
- Wall of the controls: 39 inches [1000 mm]
- Contour walls: 1 inch [25 mm]
- Floor: None
- Electrical Requirements: The unit must comply with CSA C22.1/NFPA 70 and local electrical codes. Specific voltages and amperages are indicated on the unit's nameplate.
- Fan Control: Variable speed drives (VFDs) are used for fan control, with input signals (e.g., 0-10Vdc) dictating fan speed (Hertz) and corresponding CFM.
- Temperature Setpoint Range: The internal controller aims to maintain a supply setpoint adjustable from 50°F to 75°F (10°C to 24°C).
- Temperature Differential: Adjustable from ±2°F to ±10°F for recovery mode activation.
- Recuperator Cycle Time: Varies between 20 to 120 seconds in maximum recovery mode, and 60 minutes in minimum recovery mode (cleaning mode).
- Damper Movement: The system features 2x panels of 4 sections of dampers with symmetrical movement, driven by a motor that rotates clockwise. A damper position sensor ensures optimal detection.
- Airflow Measurement: The unit can display supply and return airflow (CFM), calculated using pressure sensors (SAF1, RAF1) and a K-factor (factor according to fan selection).
Usage Features
- Human Machine Interface (HMI): The unit is equipped with an HMI for local control and monitoring. The HMI allows users to:
- View the unit's status, including supply and outdoor temperatures, and fan operation.
- Start/stop the unit (in local mode).
- Adjust setpoints for supply temperature and fan airflow.
- Monitor temperature readings from various sensors (outside, supply, return, exhaust).
- View and clear alarms.
- Access timer options for scheduling unit operation (Stop, On/Off, CFM changes).
- Adjust clock settings (time, day, date).
- Configure communication settings (BACnet MS/TP, BACnet IP, Ethernet).
- Modify calculation parameters for airflow readings (K-factors).
- Manually control recuperator damper rotation (for qualified personnel).
- Change the display language (French/English).
- Remote Control: The unit can be started and controlled remotely via dry contact signals or BACnet communication, allowing integration into building management systems.
- Alarm System: The unit provides notifications for various alarms, including recovery unit fault, temperature sensor fault, clogged filters, high humidity control, and low temperature limit. Alarms are displayed on the HMI and can be sent as dry contacts or via BACnet.
- Password Protection: Access to certain settings and advanced menus on the HMI is protected by password levels (Level 1 for communication, calculation, recuperator; Level 5 for PID and advanced menu).
Maintenance Features
- Filter Inspection and Replacement: Filters should be inspected weekly and replaced if necessary, meeting UL 900 requirements for Air Filter Units. Filters must be supported on all four sides to prevent damage to exchanger dampers.
- Obstruction Checks: Regular checks are required to ensure that air inlets and outlets are not obstructed.
- Drainage System: Drains must be checked for clogs and cleared as needed.
- Motor/Fan Bearing Lubrication: Bearings should be lubricated as required.
- Recuperator Inspection: Periodically check for loose components on dampers, engine plates, or linkages, and retighten if necessary.
- Safety Control Verification: All safety controls must be checked for functional operation.
- Electrical Connection Checks: All electrical connections should be inspected for tightness.
- Fan and Motor Anchoring: Ensure that fans and their motors are firmly anchored.
- Recovery Block Cleaning: While effective air filters should minimize the need for cleaning, recovery blocks can be cleaned using a vacuum cleaner or pressurized air if necessary. Detergents or solvents are not recommended as they can damage heat exchange surfaces.
- Startup Report: A detailed startup report form is provided to document initial inspections, verification of motor rotation, engine amperage, control sequence, noise levels, airflow, HMI status, and any adjustments made.
- Safety Precautions: The manual emphasizes critical safety warnings, including the need for qualified technicians for installation and maintenance, disconnecting and locking out power before servicing, and avoiding bypassing safety switches. It also warns about the sudden movement of motors, linkages, and dampers, and the risk of crushing.
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