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How To Inspect Heating Ducts

Your heating (and air-conditioning) ducts are large diameter pipes that carry warm air from the furnace to each room of your home. These ducts are usually run through the attic and/or under your home. Typically they are run through what is known as unconditioned space. That means they are exposed, at least indirectly, to the outdoor temperatures. As a result, they have the potential to lose a lot of their heat before they reach the heat register in a room.

To reduce the loss of energy to either warm or cool air, carried through the ducts, the ducts are insulated and sealed together with duct tape. However, over time, the insulation can slip off, exposing the duct to the elements. Also, the tape that seals ducts together can come off, allowing conditioned air to be pumped out through the opening. Both conditions can to lead significant energy loss, greater heating and cooling costs and a less comfortable home.

While not much fun, periodic inspection of heating ducts can lead to significant savings. Plus, doing inspections only once every two or three years should be adequate.

The best way to conduct the inspection is to turn on the heater or air conditioning, depending upon the season. Be sure to set the thermostat to "ON" instead of "AUTO" so that it stays on throughout your inspection. Give the system a few minutes to operate and get to operating temperature.

Whether you have to crawl under your house or into your attic, the first step is to simply observe. Take a flashlight and scan the ducts for any obvious missing insulation or sagging insulation. Also look for signs of a draft, moving insulation, or cobwebs can tip you off to an opening in the ducts.

Next, get as close as you can to each duct and make a closer inspection for adequate coverage by insulation and very importantly, for gaps that may have opened up in the insulation or between segments of the ducts. Repair any gaps you find.

There is a tool that can make this project a lot easier, an infrared thermometer. The thermometer is hand held and pointed at an object to measure its temperature. Because it can be used at a distance, it can reduce the amount of crawling around the attic or underneath the house. While it is less accurate as the distance increases, it is still accurate enough to reveal problem spots. There are several models on the market in the $50 range. Read our review of one model, the General Tools Heat Seeker, in our Tool Review section.

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