Underwriters Laboratories Testing Program

In 2009, Rawal Devices contracted with Underwriters Laboratories’ HVAC Testing Facility in Plano, Texas. With no truly representative testing model available through conventional sources, Rawal Devices secured a third-party evaluation of the APR Control against similar performance demands for a standard (straight) cooling system and a system with simple hot gas bypass part-load control. While this test offers a loaded-run comparison at identical load conditions, it is a poor comparison for demonstrating the benefit of the APR Control for extended runtime operation. (1)

Our test consisted of a single unit which was outfitted with an APR Control and standard hot-gas bypass (HGBP). Depending on the condition being evaluated, the unit operated without either valve open, with the APR Control open, or with the HGBP open.

The results we obtained supported our position that the APR Control is an efficient and cost-effective solution to many common HVAC problems. We found the following:

  • Energy savings: When the APR Control was used, the unit’s energy consumption (measured in kW) was LOWER than when it was not used.
  • Cost effectiveness: When compared to HGBP, the APR Control offered a 12% improvement of BTU/Watts (EER). In addition, this test revealed that the APR Control provided better system latent performance. And the APR Control was far more stable and held suction pressure far steadier with less hunting and system fluctuation.

Since the APR Control modulates the air conditioning system, the Energy Efficiency Ratio is inapplicable. By design, the APR Control lowers the apparent efficiency by reducing capacity thereby lengthening runtime to accomplish comparable dehumidification. Since the units lack a common baseline, the EER ratio becomes useless in this situation.

(1)Since the APR Control modulates the air conditioning system’s output and extends runtime, its benefits are more apparent with longer runtimes (6-24 hour cycles and longer).