ANAHEIM, Calif. - ASHRAE researchers reported that compared to R-22, R-410 split systems tend to lose efficiency when they are exposed to temperature extremes - around 125 degrees F and higher. These temperatures are typical of many rooftop environments in summer.

There were limitations to the research project due to equipment limitations. For instance, at 135 degrees, the R-22 compressor shut itself off on a safety. Likewise, at 135 degrees the 410A compressor's internals shut down after 20 minutes of operation. Fortunately, the researchers were able to obtain a new compressor under development, and convinced the manufacturer to remove its safety controls in the name of research.

"We had a special compressor constructed without safeties so we could run it until we blew it up, which we did," remarked Keith Rice, Ph.D., a researcher from Oak Ridge National Laboratories, Oak Ridge, Tenn.