House & Home

Take Care of Ducts Now for Greener, Cheaper Winter Heat

Posted September 16, 2014

How can you prepare for a healthier, energy-efficient, and money-saving winter? Take care of your HVAC ductwork by cleaning, repairing, and insulating it as necessary. Proper attention to the air duct system is an easy, inexpensive step toward improved air quality and more efficient heating. Why not take care of this task now, before winter's cold sets in?


Routine vacuuming or dusting of your HVAC registers is important, but cleaning further inside the ductwork is not necessary on a regular basis. However, there are certain circumstances that warrant cleaning the interior of your ducts ASAP -- for your health's sake. If you see mold growing inside your HVAC ducts, it is essential to clean the system to avoid allergies, asthma, and other breathing problems. Occasionally vermin or insects will make their home inside the ductwork; have the pests removed pronto and the ducts thoroughly cleaned. During home remodeling, the duct openings should be well covered. However, if any debris from lead paint or asbestos, or large amounts of dust, has entered the ducts, they must be cleaned urgently. Finally, if you find that unpleasant odors, animal hair, or other contaminants are coming into the ambient air via your ductwork or a household member is suffering from an unexplained respiratory illness, persistent headache, or rash, duct cleaning is strongly advised.

NOTE: Never use a steam cleaner on your ducts, as you do not want to introduce large amounts of moisture into the system. While you can clean the surface and ends of ducts yourself using a rag lightly dampened with bleach solution, you will not be able to reach as far as a trained serviceperson armed with a professional duct-cleaning machine.

Repair Leaks

Your duct system can leak due to either holes in individual duct pipes or poor connections between pipes. These leaks may reduce the heating and cooling ability of your HVAC by up to 20 percent, while at the same time increasing greenhouse gas emissions. Even worse, they might backdraft life-threatening gases such carbon dioxide from your furnace or other appliances into your living space.

Leaks can be difficult to find since the ductwork runs through small hard-to-get-at areas such as crawl spaces. To try to track down sources of leakage, turn the HVAC thermostat to "on" instead of "automatic." This will allow you to feel for escaping hot air as well as visually inspecting the ducts.

Turn off the HVAC and apply mastic sealant, metal tape (NOT ordinary duct tape, which doesn't last long enough), or aerosol sealant to repair any leaks or faulty connections that you discover. Especially large gaps may need to be filled in with insulation before using the mastic.


Insulation can help conserve the cool air produced by your HVAC system in summer and warm air in winter, reducing energy consumption and saving you money on utilities. It's easy to determine whether insulating your ducts is a good idea. Just evaluate the difference in temperature between the air running through your ductwork and the air around it. This tends to be particularly pronounced in northern locales when your ducts go through an uninsulated attic space. For example, if your HVAC is sending air through the ducts at 68 degrees F and the surrounding area under your Chicago roof is a chilly 40 degrees or less, insulation is an excellent idea.

Material for insulating ducts comes in sleeve or blanket style, with the latter being easier for a DIYer to apply. Typically, it consists of cotton, foam (use only non-flammable foam created specially for this purpose), fiberglass, or bubble wrap backed with foil as a moisture barrier. The cotton type is the most eco-friendly variety. Choose the best R-value for your locale.

Laura Firszt writes for

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