In commercial buildings with high ceilings, temperature differences between the floor and ceiling can change throughout the day, particularly during heating season. For facilities using destratification fans, the control strategy determines how fan operation responds to those changing conditions.
Temperature-based fan controls allow facilities to automatically adjust air circulation using measured temperature differences rather than relying exclusively on fixed-speed operation. Understanding the available control options is important when specifying a system for an existing HVAC installation.
What Is Delta T Control?
Delta T (ΔT) represents the temperature difference between two measurement points. In an Airius destratification system, temperature sensors installed near the ceiling and floor provide measurements used to control fan operation.
The Airius Delta T Fan Control adjusts fan speed based on the measured temperature differential. As the difference changes, the controller responds according to its configured settings, allowing circulation to adapt without continuous manual adjustment.
What Control Options Are Available?
The Airius Delta T Fan Control offers six control functions:
- Delta T control: Adjusts fan speed based on the temperature differential between the sensors.
- BAS integration: Accepts a 0–10VDC control input for fan speed control across eight steps.
- Thermostat control: Activates fans at a selected speed when a temperature setpoint is reached.
- Humidistat control: Activates fans at a selected speed when relative humidity reaches a configured threshold.
- Manual control: Provides eight selectable fan speed steps.
- 24-hour timer: Allows fans to operate according to a daily on/off schedule.
Delta T control packages are available for compatible AC and EC fan configurations. The appropriate package depends on the fan motor and electrical requirements.
Explore Airius fan controls and specifications.
How Does Delta T Control Differ From BACnet Integration?
Although both approaches support automated fan operation, they serve different purposes. Delta T control uses local temperature measurements to regulate fan speed based on the vertical temperature differential. Its BAS mode also allows fan speed to be controlled through a 0–10VDC input.
For compatible EC fan systems, Airius separately offers the AiriusBAC24 BACnet MS/TP control device. This enables individual fan on/off control, speed control, and RPM monitoring through a BACnet MS/TP network. One AiriusBAC24 device is required per fan.
The appropriate approach depends on whether the facility needs local temperature-based control, an external control signal, or individual fan integration with an existing building automation system.
What Should Engineers Consider When Specifying Fan Controls?
Control selection should account for motor compatibility, sensor placement, electrical requirements, wiring, and the facility’s existing automation infrastructure. For Delta T operation, ceiling- and floor-level sensors must be positioned to provide representative temperature measurements. Installation requirements also differ between AC and EC packages, making it important to reference the documentation for the selected system.
Airius provides separate technical resources for Delta T AC controls and Delta T EC controls, including installation instructions, wiring information, and operating procedures.
Should Destratification Fans Run Continuously or Automatically?
Both continuous and automatically controlled operation can be appropriate, depending on the building and its airflow requirements. Continuous operation maintains circulation at the selected fan speed. Temperature-based operation allows fan speed to respond to changes in the measured ceiling-to-floor temperature differential.
The selection should reflect the facility’s operating conditions, HVAC configuration, and control requirements. Automatic operation provides an additional level of control, but energy performance depends on the application and how the complete system is configured.
Specify the Right Controls for Your Building
Fan selection and placement are important components of a destratification system, but the control strategy also determines how that system operates. Airius offers temperature-based controls, manual speed controls, and building automation integration options for compatible fan models. Selecting the appropriate configuration allows engineers and facility managers to align fan operation with their building’s requirements.
Explore Airius control solutions or request a quote to discuss your facility’s control requirements.