Onset’s Hobo U-Series temperature and motor on-off data loggers were selected for an air-conditioning system monitoring pilot program in San Joaquin Valley, Calif.

The nine-week study, funded by the California Energy Commission, will look at energy savings realized through the use of an enhanced fan delay, which is a retrofit device HVAC contractors can apply to residential air conditioners to improve cooling performance in hot-dry climates.

“After a system’s compressor shuts down in hot-dry environments such as the Western U.S., water that has condensed on the evaporator coil can be re-evaporated into the conditioned space to boost the sensible efficiency of the unit,” said Adrian Hairrell, an engineer with Proctor Engineering Group, the San Rafael, Calif.-based engineering consulting firm developing the devices.

“The purpose of this study is to compare the energy use of a standard system to that of the same system with the enhanced fan delay control added. Our goal for the project is to realize at least 7 percent energy use savings in each California climate zone we monitor.”

The monitoring period for each participating home started in May and ran for approximately nine weeks. All participating homes are located within the San Joaquin Valley region, where summertime temperatures can reach 115°F and lead to heavy air conditioning use among residents.

The Onset data loggers were installed on the air-conditioning units to measure supply and return air temperatures, fan and compressor runtime patterns, and compressor amperage. The recorded data will be offloaded onto a computer using accompanying Hoboware graphing and analysis software, and then exported into a spreadsheet program for detailed analysis.

“In the past, we’ve used data logging devices that could take up to eight hours to install at each site, which can be very imposing on the homeowner,” Hairrell said. “One of the benefits of the Onset loggers is that they can be installed very quickly - minutes versus hours - so the homeowner doesn’t have to spend a lot of time waiting around.”

The results of the study are to be published in a report in early 2011.