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HVAC Technician Inspecting a Home Duct System

15 Feb 2022

Author: Jeff O'Hara

There’s an entire subsystem that exists between the outlets of your air conditioners and furnaces that is used to distribute treated air to the HVAC vents in your walls and ceilings. This network of galvanized steel ducts is connected to flexible conduits that distribute conditioned or heated air to every room of your home.

We rarely see any of our HVAC ductwork as it’s sealed behind walls, above ceilings, or hidden in the attic beneath layers of insulation. As a result, we’re not likely to think about our HVAC ducts very often (if at all); until we discover a problem with what is coming out of our HVAC vents.

Heating issues will be blamed on a faulty furnace, and likewise, any problems related to cooling your home will be blamed on the air conditioner. What if neither of them was at fault for your too-chilly bathroom or that one bedroom that always feels like a sauna?

AC ducts need to be inspected starting five years after installation and every other year after that.

What are HVAC Ducts Made Of?

There are three different types of materials used in the fabrication of HVAC ductwork:

  • Sheet Metal Ducts:

    Constructed of either galvanized steel with a rust-proof zinc coating or aluminum, used primarily in commercial HVAC systems. Sheet metal is easy to cut and form into various shapes; it protects against air losses, has better airflow properties than other duct materials, and keeps fungus and mold from growing. Sheet metal ductwork can be noisier than other options due to the “metal-to-metal” contact with HVAC outlets or other metal duct pieces. Sheet metal ducts take a long time to install, as measuring and cutting each section is time-consuming. Needless to say, sheet metal ducts are the most expensive choice when replacing ductwork.

  • Duct Board:

    Formed panels are made of fiberglass and have an insulating aluminum foil outer wrap; duct board can be used in place of sheet metal ductwork in commercial and residential applications. Duct board is pre-fabricated into common sizes and forms used in various installations and does not require a layer of insulation to be installed around it, as sheet metal requires. The duct board has less potential for causing rattling and knocking sounds where it joins the HVAC system, as fiberglass doesn’t reflect sound waves.

    The downside of duct board material is that unless the fiberglass is chemically treated, the layers of fiberglass can get damp, leading to the growth of mildew and mold.

  • Flex-Duct:

    Easily, the most commonly “seen in the wild” species of ductwork is the flex-duct. Think of the flex duct as a giant “Slinky” toy wrapped in plastic and insulation. Flex ducts are easy to install and a much cheaper alternative to an entire duct system made of rigid sheet metal or duct board.

    The biggest downside of flex-ducts is their flexibility. As the materials that make up the flexible plastic begin to break down due to exposure to extreme heat and cold, small cracks can form in the sheathing. Any unrepaired opening in the duct will allow untreated air from your attic to enter the living space, increasing the amount of dust in the home. As conditioned air escapes into the attic or between the walls, you could be losing as much as 40% of your home’s energy bill through that opening. Also, longer lengths of flex-duct are often installed without adequate support, leading to crumpling of the ducts and cutting off airflow.

What Can Possibly Go Wrong with My HVAC Ducts?

From a technical standpoint, there isn’t a lot that can go wrong with your HVAC ductwork, and it’s essentially a maintenance-free system. Other than occasionally dusting off the faceplate of your HVAC vents, there isn’t much a homeowner can do for their ducts.

Why Would I Need My Ductwork Inspected?

Unless you owned your home when the current ductwork was installed, you probably have no idea what shape the ducts are in or what they’re made of. Many of the ductwork repair needs that we see result from poorly done installations. Our technicians can evaluate your entire duct system and offer repair or replacement recommendations based on what they find.

Flex-ducts in the attic will be visually inspected for tears that can draw musty attic air into your HVAC system, circulating it around your home. Any joints, either between steel duct and flex-duct or between sections of flex-duct, are checked using a smoke pencil for any possible air leaks. It is common for areas of flex-ducts to separate, as these joints are exposed to high temperatures, extreme humidity, and vibration from the air flowing through them. Your technician may reinforce these connections using duct tape.

Should I Be Having My HVAC Ducts Cleaned?

Unless there is visible mold, mildew, or other fungal growth, or if there is an insect infestation of the home that needs to be addressed, there is no reason to have HVAC ducts professionally cleaned. In the only study ever conducted on the benefits of HVAC duct cleaning, the Environmental Protection Agency (EPA) found no improvement in dust levels occurred following duct cleaning.

Nick’s Plumbing & Air Conditioning includes a comprehensive inspection of all exposed HVAC ductwork with our regular, annual HVAC maintenance service. By exposed ductwork, we’re referring to any ductwork that can be seen without removing drywall or opening a ceiling. We check all supply and return vents, ensure that all registers are open and functional, and for adequate airflow.

Call Nick’s today to schedule your annual HVAC maintenance service, and while your technician is at your home, as about our HVAC VIP Maintenance Plan. In addition to regularly scheduled maintenance service, enjoy prioritized service and special discounted offers available only to VIP Plan members.

Visit our VIP maintenance plans page for more details. Call Nick’s Today. We’re on the Way!

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