variable speed, SEER improvement, scroll, rotary, condenser fan
Homeowners in the United States can generally choose among three types of air conditioning systems: fixed-speed compressor systems that cycle on and off to deliver an average cooling capacity; fixed-speed / multi-capacity compressor systems with reduced cycling; and variable speed compressor systems that match the cooling load of the household, thereby delivering better temperature and humidity control with higher efficiency and comfort levels. While HVAC systems account for about 45% of the energy consumption in U.S. homes and variable speed compressor systems can achieve significantly higher efficiency, they only account for 10% of the market and systems installed in new buildings mostly remain single speed. This could be explained in part by the initial system cost and the complex electronic circuitry used to vary compressor speed. This paper presents a system solution to improve the Seasonal Energy Efficiency Rating (SEER) of Permanent Split Capacitor (PSC) compressor systems by introducing a low power inverter used only for operation at low capacities. SEER results for 3 tons and 5 tons systems with scroll and rotary compressors are presented. The impact of varying the speed of the PSC outdoor fan on SEER is also discussed.