Ductwork installation is a complicated process. But this guide will explain what it entails. We’ll break down the basic parts of a residential duct system and the steps required to install it. The following insights may also help you decide whether to replace your HVAC system with the same type of equipment or consider a ductless AC system from Air Stars.
Parts of a Duct System
The main parts of ductwork and some of the most crucial components of an HVAC system (at least regarding air distribution) include:
- Plenum: The plenum is the first stage of your ductwork system. It is attached above the furnace or air handler, on the supply side, and is the largest duct (the standard size is 17.5 x 20 inches, but this can vary depending on the equipment).
- Main Trunk: While a plenum is almost always square, the main trunk can be a round or square duct. Smaller in size, trunk lines are generally attached to the sides of the plenum, at least 6 inches below its top. The main trunk line extends the entire length of your home and often reduces in size with distance to maintain a constant air velocity.
- Branch Lines: The branch ducts attach to the main truck and lead to the supply registers in each room. They’re usually about 5 inches in diameter. The number of branch runs varies with each ductwork installation. In colder climates, supply air registers should be placed on the floor close to an outside wall and under a window. In warmer climates, they should be installed in the ceiling.
- Return Air System: An equal amount of air must be returned to the furnace or air handler that is delivered to your home. The air is then reconditioned (heated or cooled) before being routed back to the supply system. Both systems typically use the same types of components. Depending on your home, one or multiple return air inlets may be needed.
Ductwork Installation Considerations
There are numerous variables to consider when installing ductwork. A technician will first determine how much ductwork they’ll need to complete the installation. This step requires a detailed and scaled floor plan of your home, as precise measurements are critical. Other factors to consider include:
- Ideal Locations for Inlet and Outlet Vents: Placing the vents in optimal locations helps improve airflow and comfort.
- Pathways to Route Ducts: Branch ducts should have as few turns as possible to avoid restricted air flow and increased pressure.
- The Amount of Air Each Room Requires: Calculating the volume of air each room needs helps correctly size the ductwork serving it.
How Are Ducts Installed?
To assemble square sheet metal ducting, measure the required length of the duct and cut it with tin snips. Duct sections come in halves. So, you’ll need to repeat this process and line the seams of both pieces. To fit the top seam into the bottom, pry the groove on the bottom piece open with a screwdriver then tap a hammer along the duct to snap the assembly together. Now, the groove is laid over the top of the side edge of the duct.
To hang square ducts, measure the distance between the bottom of the ceiling joist and the bottom of the air duct, and add two inches. Cut an S cleat to this length and drill it into the joist beside the duct. Fasten the bottom fold to the bottom of the duct. Round duct, used for branch supply lines, comes in 5-foot sections that snap together. But you’ll need to know how to join the crimped and non-crimped ends and properly wrap the seam.
Installing ducts isn’t difficult for someone with experience. But as you can see, it requires quite a bit of time and effort.
The Ductwork Installation Process
Here’s an overview of the process a licensed HVAC professional uses:
Create a Plan
To create a layout of the ductwork, a technician will calculate heat loss and heat gain in each room. They’ll determine where to place the air conditioner unit, the furnace, and the exhaust vents. Next, they’ll decide on the best types of ducts to use. Galvanized steel is common, but other types of rigid and flexible ducts exist.
Duct Vents Are Installed
Holes are cut in the drywall to make room for the duct vents. The supply and return vents may be of different sizes, depending on your home’s layout. The ducts will be run from the main heating and cooling units and air handler to these openings.
Air Ducts Are Installed
Once your HVAC system is set up, the technician will configure the ductwork based on the layout of your home. They’ll also consider energy efficiency. Once the ducts are placed, they will be sealed with metal-backed tape or a mastic material to prevent air from escaping, which is a leading source of energy wastage.
Mistakes to Avoid
A successful ductwork installation will yield years of reliable, efficient HVAC performance. However, any mistakes can leave you with long-term problems that reduce efficiency, comfort, and possibly indoor air quality. These are some mistakes that can result in persistent issues and costly repairs:
- Zig Zags: Poor airflow reduces energy efficiency and can increase your energy bills. Whenever possible, ducts should be installed in straight lines.
- Gaps in Ducts: Oftentimes, ductwork is improperly installed with sections, joints, and transitions not fully sealed. These gaps make ductwork leaky.
- Incorrect Sizing: Your HVAC system and ductwork must be sized based on the square footage of your home. Otherwise, uneven temperatures can result and your system may be damaged.
- Unbalanced Airflow: Installing too few return vents creates an imbalance that reduces system performance. Return vents should be installed in the living room, all bedrooms, the basement, and the hallway.
- Not Hiring a Professional: A licensed technician has the training, tools, and experience to provide high-quality ductwork installation. They can also anticipate any issues and work out solutions to ensure your duct system is functional and efficient in the end.
Call Air Stars for Professional Duct Sealing and Insulation
You not only need a professional for ductwork installation but also duct sealing and insulation services. At Air Stars, we specialize in improving ductwork efficiency. But if you’re looking for an upgrade that yields even greater energy savings, we can provide ductless heat pumps. To schedule HVAC service in and around Salem, OR, call (503) 304-1320 today.
