Types of Air Ducts
Air Duct Cleaning Utah are an essential part of your home’s HVAC system. They take dirty air and filter it, heating or cooling it as needed. They also distribute conditioned air throughout your home.
If you’ve noticed the dust collection in your home is out of control or your family members are sneezing more than usual, your ductwork might need to be cleaned.
Sheet metal ducts are durable and customizable, making them a favorite for residential and commercial applications. They can be made from various materials, including galvanized steel with a rust-resistant zinc coating or aluminum. In addition, they can be formed into multiple geometric shapes to accommodate different spaces in a home or office.
Sheet-metal ducts are fabricated using a combination of cutting and forming processes. Cutting involves shears or specialty high-definition plasma equipment, while creating uses brakes and presses to exert applied force to change the shape of a piece of metal. Both of these processes are critical in fabricating custom-made ductwork that meets specific needs for any HVAC project.
Galvanized steel is one of the most common materials used for duct fabrication, as it provides strength and durability while still being relatively affordable. However, other types of metal, such as copper or stainless steel, are also used for ducts. These ducts may require special treatment for moisture or corrosive environments but can be just as effective as their galvanized counterparts.
The type of sheet metal used in a duct will depend on the construction standards required by the job. For example, if the duct is required to support a certain amount of static pressure, it must be constructed with heavier metal gauges than a duct not subject to such stress. The local codes or the industry usually dictates these standards but may also be based on the acoustic requirements of the space.
Once the ductwork is fabricated, it must be combined using appropriate techniques. A sheet metal fabricator will normally use gaskets with bolted corner pieces to reduce the likelihood of leakage. These joints are then closed with either rivets or welding.
For larger duct sections, reinforcement is usually needed. These can be supplied as tie rods, added at each joint and two mid-way between the joints to provide additional strength. These are particularly important for larger ducts or those supporting large static pressure.
This type of ductwork is tube-shaped and typically made from a steel wire helix wrapped with a flexible polymer plastic. It’s becoming increasingly popular in new homes and is considered a superior insulation option to hard pipe ductwork. Flex ducts can be used in various applications, including ventilation, heating, and air conditioning.
The biggest advantage of a flex duct is its ease of installation. The lightweight material can bend to easily adapt to the shape of an attic space, saving time and money in labor costs. The flexibility also makes it easier to clean the duct, which helps reduce bacteria and mold build-up.
Another advantage of a flex duct is its ability to handle high temperatures. This type of ductwork is often used for exhaust systems in industrial settings and can withstand various temperatures, from cold to hot. The high-temperature capacity of flexible ducts is also ideal for woodworking and processing applications that involve heavy dust and fume extraction.
When installing a flex duct, it’s important to use good technique—using a sharp knife to cut the outer jacket, fiberglass insulation, and inner plastic core. Then, you can use shears or snips to cut the steel wire helix. After cutting the helix, you should fold back the outer jacket and fiberglass insulation and insert the sheet metal fitting.
It would be best if you were sure to stretch the flex duct tightly when installing it. This will help ensure that it doesn’t sag over time. Using a stiff wire brush to sweep away any dirt or debris in the duct’s interior is also important.
Regardless of the type of ductwork you choose, supporting the system is crucial, according to the manufacturer’s recommendations. Ducts that are not properly supported can sag or become kinked, which can reduce the efficiency of your system. Ducts can be supported by straps, factory-installed suspension systems, or saddles attached to the attic framing. They can also rest on ceiling joists or truss supports.
Traditionally, sheet metal ductwork was installed first and then lagged with insulation. However, ducts made from rigid foam boards can be fabricated by a sheet metal fabrication shop in one step. Wooden phenolic or polyurethane foam panels come with factory-applied aluminum facings and are preinsulated. A duct fabricator can trace the duct layout onto the preinsulated panels, cut them to size, and bend them as needed (i.e., elbows, tapers). Then, they glue them together. The result is an insulated, airtight, and water-resistant duct, with all connections sealed with mastic. This system is suitable for all climate zones.
The ducts are typically sized to match the heating and cooling system. These ducts are less expensive than sheet metal and can be used in all homes, including small apartments or large houses. They also work well in retrofits because they can be easily cut and shaped to fit around existing metal ductwork.
Because of the rigid nature of these ducts, they are not prone to mold or mildew growth like flexible ducts. They are also quiet compared to other duct systems, making them an excellent choice for homes where noise is a factor.
A common problem with these ducts is that they are susceptible to condensation, particularly in humid climates. The issue is caused when the temperature of the duct surfaces is lower than the dew point. A 1″ layer of cured closed-cell spray foam prevents condensation by sealing the surface, eliminating the space where moisture can form. It is worth mentioning that this method works best when the ducts are encapsulated in spray foam before being covered with loose-fill insulation.
In addition to preventing condensation, mastic-sealing all joints is essential to maintaining the thermal performance of any duct system. It is important to consult the manufacturer’s installation instructions and only use UL 181-approved pressure-sensitive tapes and sealants on duct seam edges and joints. It is also important to seal all duct hangers and clamps properly. Lastly, testing the total duct leakage and adding additional sealing as needed is necessary.
PVC is an incredibly durable material found in many construction projects. It is a common choice for plumbing applications but has several benefits when used in ducting.
PVC ducting is less expensive than metal ducts and is easier to install. It is also lightweight, meaning it requires less support for larger diameters. Additionally, it can withstand higher temperatures than some other piping materials.
PVC duct is ideal for ventilation systems because it resists corrosion and stands up to gases, fumes, and exhaust. It is also long-lasting and will require fewer repairs than metal ductwork over the years.
Unlike standard PVC pipe, often used for basic plumbing, PVC ducting has thinner walls. This makes it ideal for ventilation applications, as it can hold more air over shorter distances. It can also handle higher temperatures than standard piping, although it is not recommended for ducting heated or chilled water.
When choosing a PVC duct, it is important to select the proper sizing. The most common sizes are Schedule 40 and Schedule 80. Both suit most ventilation needs, but schedule 80 is thicker and better suited for high-pressure applications. During installation, it is critical to follow the manufacturer’s instructions carefully. PVC ducts can be joined using couplings, which slip inside the mating pipe sections and are held in place by a stop bead that runs around the center of the fitting.
PVC ducts can be connected to metal ducts but should not be run directly over them. Metal ducts are often more easily accessible for maintenance and repair, making them a preferred option for large overhead configurations. However, if PVC is used for these applications, protecting it from damage during backfilling and grading is important. It can be crushed if heavy equipment is run over it, so extra supports may need to be installed. Alternatively, temporary bracing can be used to provide additional strength. Adding angle rings to the ducts for large diameters is also possible to improve their rigidity.