Just a little heat goes a long way towards sweet, sweet profits.easy bake oven

When you consider the fact that the waste heat from just one incandescent light bulb is enough to bake cookies, you might forgive the government for forcing CFL’s upon us. When you consider what excess waste heat does to your furnace’s blower motor, as in prematurely destroys it, you might not be as forgiving of Auditor Air.

It was just yesterday that I installed a new vacuum switch for a homeowner in Walnut Creek. While making that repair I performed a routine check of the blower motor’s run capacitor. Replacing weak and failed run capacitors is, quite literally, the most common repair I perform. As such, checking capacitor strength is (or should be) as common to a furnace man as checking blood pressure is to a doctor. Just like checking blood pressure, checking a capacitor is easy and it has the potential of preventing a major failure down the road. It should be done on almost every single visit.

As you can see in the slideshow below, the capacitor in this furnace is rated for 7.5 microfarads. The old capacitor had weakened all the way down to 3.6 mF. That resulted in the blower motor drawing an extra .53 amps. That may not sound like much, but that translates to an extra 64 watts (217 BTU’s) of waste heat in a motor smaller than the toy oven above – in other words, a light bulb’s worth. Try holding a 60 watt incandescent light bulb in your hand while it’s on. The heat will damage your hand and it’ll damage your motor.

Auditor Air replaced this furnace’s hot surface igniter last winter. A typical blower motor capacitor only degrades by .1 or .2 mF per year. As such it’s a near certainty┬áthat the capacitor also needed to be replaced last year. Capacitors are cheap and easy to replace. I can’t say why it didn’t happen last year. But I can say that replacing a capacitor doesn’t add much to the bottom line. Letting a weak capacitor prematurely destroy a blower motor? That adds aplenty.

Clicking the picture will bring up a larger picture.