May 03, 2010
Electrically Commutated Motors (ECM) in air-handler fans promise improved efficiency. But does improved technology necessarily mean efficient HVAC systems?
The author completes the measurements. (Image credit: Building Science Corporation)
The two technologies used in furnace and air handler blower motors are permanent split-capacitor (PSC) or induction motors and, more recently, electronically commutated motors (ECMs), which are also known as brushless DC motors. ECMs can offer gains in efficiency, especially when their variable-speed capacity is utilized (for example, with a continuous low-speed fan for circulation and destratification, low-speed heating mode). These ECMs are widely used in higher-end furnaces and air handlers (typically referred to as variable-speed units); they are used especially in efficiency-focused work and high-end residences.
A full background on the use of ECMs in air handlers is not the focus of this article. The subject has been discussed at length in previous issues of Home Energy (see “The Electric Side of Gas Furnaces,” HE Nov/Dec ’03, p. 24; and “Motors Matter,” HE July/Aug ’00, p. 31). This article focuses instead on air handler energy use and fan efficiency. It is based on a study conducted in 2009 by the Building Science Corporation (BSC), where I work, for the Building America Program. It includes a survey of previous research, and it discusses the results of field ...
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