The objective of this project is to demonstrate a low-cost technique to convert a constant volume (CV) multizone (MZ) air handling unit (AHU) to a more energy-efficient variable air volume (VAV) MZ AHU. Demonstrations will be conducted at Fort Bragg, North Carolina; and at USACE ERDC-CERL in Champaign, Illinois. An MZ system consists of multiple ducts where each duct supplies a zone. The airflow quantity supplied to each zone is constant while the temperature of the air delivered to the zone is varied by positioning a set of "zone dampers" to mix air of two different temperatures.The conversion of a constant volume MZ air handler to variable volume focuses on equipment, instrumentation, and controls, most notably the installation of a variable speed fan. The conversion also includes upgrading the controls via programming changes or controller replacement and the installation of new or replacement actuators and sensors--including the addition of outdoor airflow measurement--needed to support the conversion.

Whereas a conventional MZ system performs simultaneous heating and cooling in order to meet the demands of the zones, the technique to be demonstrated employs a variable frequency drive (VFD) to modulate fan capacity based on the position of the zone dampers to minimize the amount of simultaneous heating and cooling required to satisfy these demands. This results in savings in fan energy, heating energy, and cooling energy. In addition, the retrofit is expected to replace older pneumatic or single-loop digital controls with microprocessor-based direct digital controls, which provide improved accuracy and reliability and allow the application of additional energy savings techniques such as automatic adjustment of the hot and cold deck discharge air temperature setpoints, after-hours (unoccupied mode) zone temperature setback and system shutdown, outdoor ventilation air flow control, and demand controlled ventilation. Application of a low-cost and efficient method of converting MZ systems to variable volume has significant potential for energy savings across the Department of Defense.

The technology saves heating and cooling energy along with fan energy. There is virtually no need to retrofit, demolish, or install ductwork or terminal units; thus this air-handler only retrofit can be accomplished for a much lower first cost than a full system VAV retrofit with VAV boxes. Due to the relative simplicity of this system, there is less system down time and disturbance to building occupants than there would be with a full VAV system retrofit. Improved performance of the renovated system also leads to improved occupant comfort and productivity. Simple payback estimates range from 2 to 15 years, depending on whether the system operates continuously or for 12 hours a day, 5 days a week. (Anticipated Project Completion - 2014)When it comes to energy recovery units, Annexair offers the largest variety of ERU’s in the industry. Each series is available in multiple configurations that include a wide range of options. The V-SIO configurations on this page represent only our most popular designs.

Our engineering sales team will be pleased to assist you in finding the perfect product among the hundreds of configurations we offer for your projects. Annexair’s makeup air units are ideal for projects that require 100% outside air. Our product line offers a large selection of units that can also be equipped with recirculation if needed. Some units are available with a fixed plate heat exchanger for dehumidification applications.ac unit filter replacement For projects where a conventional air-handling unit is required, we offer numerous possible configurations that will meet all your specifications and requirements.benefits of window ac units When your project calls for a unique system, Annexair can quickly propose a custom design. ac units for vehicles