Wireless Condition Monitoring and Maintenance for Rooftop PackagedHeating, Ventilating and Air-Conditioning

摘要

Rooftop package air-conditioners and heat pumps, while representing over half of U.S.Commercial-building cooling energy consumption, are some of the most neglected of buildingsystems. They are often found with inoperable dampers, dirty/clogged filters and coils, incorrectrefrigerant charges, failing compressors, failed fans, missing enclosure panels, un-calibratedcontrols, failed sensors, and other problems. Frequently, actual operating hours deviateconsiderably from intended (and assumed) schedules.Although there are no reliable estimates on what fraction of the units operate underdegraded conditions and the energy inefficiencies associated with such operations, a range ofsavings from 10 to 30% is generally believed to be achievable by enhancing operation of theseunits. The potential nationwide energy savings from proper operation range from 23 to 70trillion Btus annually in the U.S. Since the cost associated with conventional monitoring andservicing is quite high, conventional monitoring is seldom done. Combinations of wirelesssensing and data acquisition, monitoring tools, automated diagnostics and prognostics showconsiderable promise to help remedy this maintenance problem for package heating, ventilatingand air-conditioning (HVAC) units and the underserved small commercial building sector inwhich they are predominantly installed.This paper characterizes the current problem with maintenance of packaged airconditioners and heat pumps, provides estimates of the total energy impacts of the problem, anddescribes a generic system in which these developing technologies are used to provide real-timecondition monitoring for package HVAC units and their components. Costs with today'stechnology are provided and future costs are estimated, showing that benefits will greatly exceedcosts in many cases, particularly if low-cost wireless monitoring is used.