An Inside Look Into Your Duct System
In a forced air heating and cooling system (furnaces, heat pumps, or central air conditioners), ductwork is responsible for distributing conditioned (hot or cold) air throughout your home and returning it back to the equipment so it can be heated or cooled again and redistributed. Well-installed and maintained ductwork enables your HVAC (heating, ventilation, and air conditioning) system to run efficiently and maintain consistent temperatures.
Poorly installed ductwork will result in poor performance, bad air flow, leaky ductwork systems and higher than usual utility bills. For these reasons, it is important to have your ductwork installed correctly by qualified installation technicians whether for new construction or retrofit.
A qualified technician will take into consideration the load size. They will look at factors such as square feet of dwelling, number of occupants, which direction the house is facing, shading around the house, and number of windows and doors as well as many other factors. This is important because under sizing ductwork causes the system to strain mechanically and can be noisy and over sizing a system costs more and does not maintain the desired air flow.
The condition of your ductwork plays a major role in the overall energy efficiency of your home’s comfort system. Leaky ducts will also reduce a system’s ability to deliver even heating and cooling throughout your home. Some estimates suggest that poorly installed or maintained ductwork can increase your heating and cooling bills by up to 30%.
Indirect affects of poorly maintained ducts are that your home will be less comfortable, due to conditioned air escaping before it gets to the rooms it was designed to reach. Also, if you have an air filtration system integrated into your furnace or central A/C, it can reduce the system’s ability to remove allergens from the air. And last but not least, your furnace or air conditioner will need to cycle on and off more often, increasing the wear and tear and decreasing the efficiency of your system.
Leaks can occur at a number of points in the ductwork. There is a potential for leaks anywhere there is a joint. Small leaks in a basement duct system may not be much of a problem, however, small leaks in the supply or return ducts located in an unconditioned space such as an attic, crawlspace or garage can make a very big difference in energy usage and comfort.
You can visually inspect your ductwork yourself, although you many not find some of the more subtle problems and want to have an HVAC professional check as well. When inspecting, look for damage to the ducts, such as rips in flexible ducts, dents, or disconnected joints. Also make sure that insulation is wrapped tightly and uniformly around the ducts.
You can seal joints or leaks yourself, however, again you may want to have an HVAC professional do this for you. For narrow joints (less than 1/4 inch) you can paint HVAC mastic over the opening. Mastic is a putty-like material that is designed specifically for this purpose. For wider joints, you will need to apply fiberglass tape, and then mastic on top. Despite its name, do not use duct tape to seal your ducts. It does not adhere well or last long under dirty, dusty conditions and there isn’t anything dirtier and dustier than your duct system!
Having your air ducts professionally cleaned as part of your maintenance plan for your duct system can contribute to a cleaner, more comfortable home and better efficiency of your heating and cooling system and better health.
Layers of dirt in ductwork can affect your operating costs and comfort. Most of the dirt accumulates in the return ducts of your system, which leads back to your furnace. Since your air filter is located between the return and your furnace, dirty ducts can quickly clog up a furnace filter causing the furnace and/or air conditioner to work harder. This not only wastes energy, it can also affect your indoor comfort by delivering less cooling or heating to your home, as well as reducing the life of the equipment.
If your furnace has a standard filter, a large portion of that dust will make it through the filter. This not only coats your equipment with dirt, reducing its performance and longevity, it also blows the dirt right back into your home. You’ll be breathing in contaminated air.
Your ductwork is an important part of your HVAC system. Making sure it is installed correctly and properly maintained helps ensure equipment efficiency, lower utility costs and increased home comfort.
Sources: “Our Duct System, An Inside Look”, Contracting Business Magazine, 1996
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