Self-correcting Controls for Air Handling Units

Laboratory Test of Self-correcting Controls for Air Handling Units

Abstract
Packaged, rooftop HVAC equipment are often maintained poorly with degradation of performance and faults only addressed when occupants complain or a unit fails to operate at all. Reactive maintenance of this sort leads to inefficient operation with high energy costs and significant waste. Allowing equipment to operate with faults also often leads to further physical deterioration of the equipment, reducing equipment lifetime, and sometimes complete and catastrophic failure. With the ultimate goal of automating heating, ventilation and air conditioning equipment to detect faults and take corrective action, Pacific Northwest National Laborator (PNNL) developed and tested algorithms that implement self-correction capabilities for sensors, economizer dampers, and damper actuators in building air-handling systems.

Laboratory tests by PNNL showed that automatic self-correction of faults can be successfully performed. However, under some conditions passive detection of a fault may not be possible. The fault isolation process may also reach an incorrect conclusion under some circumstances, most commonly when closed dampers were leaking. This problem may be addressed by modifying the algorithms to automatically account for imperfections in damper sealing.

Project Team
BPA: Kacie Bedney, Tim Steele, Jack Callahan
PNNL: Michael Brambley

Timeline
2008 - 2009

Reports

• Self-Correcting HVAC Controls Final Report (2009)
• Self-Correcting HVAC Controls: Algorithms for Sensors and Dampers in Air-Handling Units (2009)