State-of-the-Art in Residential and Small Commercial Air HandlerPerformance

Although furnaces, air conditioners, and heat pumps have become significantly more efficient over the last couple of decades, residential air handlers have typical efficiencies of only 10% to 15% due to poor electric motor and aerodynamic performance. These low efficiencies indicate that there is significant room for improvement of air handler fans. The other 85-90% of the electricity used by air handlers is manifested as heat. This extra heat reduces air conditioning cooling and dehumidification performance and effectively acts as fuel switching for fossil fueled furnaces. For electric furnaces, this heat substitutes directly for the electric resistance heating elements. For heat pumps, this heat substitutes for compressor-based high COP heating and effectively reduces the COP of the heat pump. Using a combination of field observations and engineering judgment they can assemble a list of the problems that lead to low air handler efficiency and potential solutions to these problems, as shown. None of the problems require exotic or complex solutions and there are no technological barriers to adopting them. Some of the solutions are simple equipment swaps (using better electric motors), others require changes to the way the components are built (tighter tolerances) and other relate to HVAC equipment design (not putting large fans in small cabinets)