Electric VAV control gains in DDC systems. (annual energy management system technology report - variable-air-volume boxes in direct digital control systems)

Electric VAV Control Gains in DDC Systems

LOS ANGELES--At least four building control manufacturers have recently introduced, or are about to introduce, microprocessor-based controllers which, combined with sensors and electric actuators, are designed to replace pneumatic control of variable-air-volume boxes in direct digital control energy management systems.

The controllers, which are dedicated to single VAV boxes, replace traditional pneumatic components of VAV control such as thermostats, receiver/controllers and pneumatic actuators. Although the devices are initially more expensive to install than pneumatic control equipment, they can be significantly cheaper to operate over time, sources said.

Most of the systems available can operate in conjunction with energy management system and can also operate on a standalone basis.

Staefa Controls, San Leandro, Calif., one of the first firms to manufacture such controllers, has offered them for several years. Last week, Novar Controls Corp., Barberton, Ohio, introduced a new microprocessor-based controller; and the Trane Co., LaCrosse, Wisc., recently began offering the controllers built into its new VAV boxes.

Johnson Controls Co., Milwaukee, and Robertshaw Controls Co., Richmond, Va., plan to introduce such controllers in the near future, according to company spokesmen.

Manufacturers and industry sources claim that replacing pneumatic …