Drives for fans in residential buildings

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Optimize comfort and energy consumption in building ventilation

With user-friendly interfaces, distributed intelligence and reduced power consumption, Danfoss AC drives optimize the performance of fans.

The VLT® HVAC Drive and VLT® Refrigeration Drive convert velocity pressure sensor values into flow values, enabling setup based on fixed flow or fixed differential flow. This optimizes both comfort and energy consumption. To improve comfort levels even further, drives connected to fans can be set to avoid the frequency bands which create resonance and damage in the ventilation system.

Extended building management system capacity

When integrated into a building management system network, to extend the capacity of the controller, all HVAC drive I/O points are available as remote I/Os. For example, room temperature sensors (Pt1000/Ni1000) can be directly connected to the system. 

Improved air-handling performance

The VLT HVAC Drive and VLT Refrigeration Drive are fitted with a built-in Smart Logic Controller and four auto-tune PID controllers to control air-handling functions with fans, valves and dampers. The direct digital controllers of the building management system are released and valuable data points are saved lowering air-handling costs.

The VLT HVAC Drive handles logical rules and input from sensors, real-time functionality, and time-related actions. This enables the AC drive to better control a wide range of functions:

  • Weekend and working day schedules
  • Cascaded P-PI for temperature control
  • Flow balancing between fresh and outlet air
  • Belt monitoring – from the relation between current and speed, the AC drive is able to reliably recognize a broken belt. Lack of air flow is detected immediately so that action can be taken to reduce costs and downtime
  • VLT Pressure Transmitter PTU 025 with 4 pressure sensors to monitor filters and measure airflow and pressure in ventilation systems
  • Remote LCP Mounting Kit allows the AC drive to be mounted close to the fans inside air handling units and rooftop units, whilst the local control panel is mounted outside for easy access and operation 

Reliable harmonic mitigation

While AC drives increase precision, save energy and extend application lifetime, they also introduce harmonic currents to the grid. If not kept under control, harmonic currents can affect the performance and reliability of generators and other equipment.

To ensure minimal disturbance, read more about our harmonics application know how, software tools and harmonic mitigation solutions.

EC+ Concept

When building an HVAC system, to get the highest performance and system efficiency, the individual components – motor, drive and fan – need to be flexible and broadly compatible with each other. For instance, if you specify a high-efficiency motor that is only compatible with lower efficiency fans, the overall system efficiency would suffer and would not reflect the high performance – and investment – in the individual components.

Danfoss Drives’ EC+ concept allows ventilation system designers to combine a VLT® HVAC Drive with the most efficient fan and high-efficiency permanent-magnet or synchronous reluctance motor.

Advantages of the EC+ concept

  • Free choice of motor technology: PM, asynchronous or synchronous reluctance with the same AC drive and software
  • Device installation and operation remain unchanged
  • Manufacturer independence in the choice of all components
  • Superior system efficiency thanks to a combination of individual components with optimum efficiency
  • Retrofitting of existing systems is possible
  • Wide range of rated powers for standard, PM and synchronous reluctance motors


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