Underwriters Laboratories Testing Program
In 2009, Rawal Devices contracted with Underwriters Laboratories’ HVAC Testing Facility in Plano, Texas. We secured a third-party evaluation of the APR Control against similar performance demands for a standard (single stage) cooling system and a system with simple hot gas bypass part-load control.
The testing consisted of a single unit with an APR Control added to the refrigeration circuit. On the same unit, in order to conduct additional testing, a standard hot-gas bypass (HGBP) was also installed. Depending on the condition being evaluated, the unit operated with
- both part-load control devices/valves closed, inactive in the circuit
- with the HGBP open and active in the circuit (APR Closed)
- with the APR Control open and active in the circuit (HGBP Closed)
The testing demonstrated that the APR Control is an efficient and cost-effective solution to many common HVAC performance limitations. We found the following:
- Energy savings: When the APR Control was active in the circuit, the unit’s energy consumption (measured in kW) was LOWER than when it was not active.
- Cost effectiveness: When compared to HGBP, the APR Control offered a significant improvement in kilowatts per hour (kW/hr). This test also revealed that the APR Control provided better system latent performance. Testing also showed the APR Control was more steady and held suction pressure stable with less hunting and system fluctuation.
By design, the APR Control reduces capacity thereby lengthening runtime to accomplish dehumidification. The APR produces only the BTU capacity necessary for true load matching, reducing the kw/hr to meet necessary room criteria.
Since the APR Control modulates the air conditioning system’s output and extends runtime, its benefits, especially with regard to consistent latent removal, are more apparent with longer runtimes (6-24 hour cycles and longer).
In addition, in the 10 years since this test was conducted, additional OEM testing (both with and without evaporator fan VFD modulation) has revealed further reduction in power consumption during variable capacity operation and operating at part-load conditions.