Sky Heating & Air Conditioning provides Portland-area customers with ductwork services, including installation, replacement, and sealing. Installing ductwork in existing walls can be challenging, especially in older homes not designed to accommodate a bulky central AC system. Whatever the age or condition of your home, we’ll explain how to install ductwork in existing walls so it’s less confusing.

Installing ductwork can double the cost of installing a central air conditioning system. It’s therefore important you get it right. Homeowners often believe installing ducts requires tearing apart their walls and ceilings. But this often isn’t the case, especially if your home doesn’t have a flat roof.

Some Ductwork Installation Steps

Every home is different, but here are the general steps every ductwork installation project should follow:

• Design the System: First, calculate the heat loss and gain in each room; a load calculation helps determine where you need the ductwork to go. Draw a diagram showing which rooms the ducts will serve, with room measurements included.
• Choose a Duct Type: The type of ducting matters on many levels. Sheet metal ductwork is durable and long-lasting if installed properly. There are also many sizes and fittings to choose from, suiting it for many types of homes. However, flexible fiberglass, while often easier to install, can be hard to clean and tends to degrade over time.
• Plan Where HVAC Components Will Go: Choose a location for larger HVAC components and parts, focusing on the ease of connecting everything. Then, considering how to install ductwork in existing walls becomes a little less complicated.
• Configure Ducts to Maximize Airflow: Shorter runs make it easier for your HVAC system to move air. It’s therefore wise to avoid longer runs. Placing AC equipment closer to the rooms it serves helps as well. Bends also affect airflow, especially when they’re too sharp or too numerous. Decreasing the volume of air that can reach an area, bends also reduce cooling and force the system to work harder.
• Use Existing Ductwork If Possible: Don’t reuse any parts that are worn or outdated. If parts of your existing duct system are salvageable, you’ll want to follow some best practices. For example, a butt joint can be used to install a pipe between two others when you don’t have the proper overlap. A draw band connector can help secure circular ductwork.
• Seal the Ducts: If not properly sealed, ductwork can lose 20% to 30% of conditioned air.1 In a higher efficiency system running at a lower speed, air can more easily escape through joints and small holes because it remains in the ducts for longer. Metal-backed tape or mastic gum can be used to avoid leaks.

Tips for Ductwork Installation in Existing Walls

It may be possible to connect new ducts to old ones. Foil tape is typically used between duct sections. To disassemble sections, score the seam first; then remove any screws securing duct sections through the tape. Peeling off the tape will make it more difficult to reapply new tape later.

High ceilings are an appealing hallmark of older homes but can present challenges when installing ductwork. One option is to lower the ceiling so you can hide the ductwork above the new surface. Boxed corners can be created to hide ducts, or you can install your heating and cooling system below the floor; the only cutting will be for holes to place the vents.

You can also run ducts through wall studs or webbed eco joists between floors. If you have a single-story home with an attic, you can place the ducts there and connect them to in-room registers. In a two-story home, ductwork can be run from the attic to the bottom floor through second-floor closets. It’s a non-imposing way to run ducts if reducing closet space isn’t an issue.

Then again, if you have no space at all to spare, you can install a packaged unit on the roof or a ductless mini-split system that allows for zoning

Contact Sky Heating & Air Conditioning

We generally advise homeowners not to install ductwork themselves. There are numerous considerations and many issues can arise. Our trained HVAC technicians know how to install ductwork in existing walls for all types of homes and HVAC systems. We can design, upsize, and coat ductwork with an antimicrobial sealant. To learn more or schedule service, call (503) 673-9083 today.