There is a common misconception that a commercial kitchen ventilation system relies solely on the controller to ensure reduced airflow. Additional components can be integrated to help enable maximum turndown and energy savings. Each piece in the complete system has specific technologies and capabilities and requires special consideration.
Controller
The XRED direct drive, roof-mounted clean air exhaust is ideal for use with short duct runs and low-resistance.
A demand controlled kitchen ventilation system (or variable volume system) is responsible for detecting changes in a commercial kitchen’s cooking load and calling for the appropriate level of airflow. A common detection method utilizes temperature sensors mounted in the hood above the appliances, as heat in the hood increases with increased cooking volume. Optic sensors can also be added to the control system to supplement the temperature sensors. Optic sensors detect increases in visible smoke emitted by the appliances as cooking volume increases. The exhaust and supply air fan speeds will then increase or decrease based on the change detected by these sensors in the hood.
Exhaust Fan Capable of 50% Turndown
As the cooking load varies and the sensors respond to that change, the exhaust fan speed must be capable of adjustment from the controller. Not all commercial exhaust fans are configured for or capable of fan speed turndown that is called for by the system controls. But exhaust fans that can achieve 50% airflow reduction, like the full line carried by Accurex, will result in up to 88% electrical savings. Accurex exhaust fans that are outfitted with an electronically commutated Greenheck Vari-Green® motor can provide an additional 20-70% electrical savings over standard direct drive motors in these applications.
Make-up Air Unit Capable of 50% Turndown
Accurex direct gas make-up air heaters use an ultra-efficient airflow burner that reduces energy costs and retains tight temperature control.
To ensure proper balance and maximum airflow reduction, the make-up air unit must have airflow reduction capabilities equal to that of the exhaust fan. Thus, it’s important that the make-up air unit selected for the system is physically capable of 50% airflow reduction without leading to tempering issues. With Accurex® direct gas heated make-up air units, this turndown is made possible by our patented barometric bypass damper. This damper maintains the pressure drop across the burner as air volume changes, ensuring proper combustion for heating the supply air. The bypass damper is self-adjusting and integral to the unit, requiring no controls. In our packaged cooling make-up air units, this 50% turndown capability is made possible by our draw-through design which allows for maximum utilization of the coil without freezing through the fully expanded airflow range.
Leveraging the combination of all three of the above components as a complete system ensures maximum electrical, heating, and cooling savings. Accurex products are designed to work together to provide a demand control kitchen ventilation system that achieves the energy savings and green building standards specified in ASHRAE 90.1, ASHRAE 189.1, IECC 2015 and California Title 24 for 50% airflow reduction. Additionally, reducing airflow improves employee and customer comfort by decreasing make-up air load and sound levels in the kitchen.
To discuss how a demand controlled kitchen ventilation system can work for your commercial kitchen, find your local Accurex representative.
