Duct takeoff provides the avenue through which air moves from a main trunk line to new branch ductwork. The type of duct takeoff you use can have significant impacts on your system’s performance.
These range from a full body fitting like a tee to a saddle tap that only has a hole on the side big enough for the connection outlet size. All of these are cost-effective but can have an impact on airflow.
Round Takeoffs
Duct takeoffs provide the avenue through which air moves from the main duct pipe to a new branch that services another area or room. These ducts play a huge role in forced air HVAC systems that use a fan to circulate conditioned air throughout the building or home. Without the proper duct takeoffs, an HVAC system may not run efficiently or evenly.
In order to properly perform a duct takeoff, you must first determine where your equipment is located and the capabilities of that piece of equipment. This information will help inform the duct size and fitments required to properly serve that equipment.
Then, you will need to select a method of connecting these pieces of duct. The type of fitting you choose will directly affect the airflow that can pass through it. For example, if you choose to connect two ducts with a scoop takeoff (a three-piece 90-degree elbow), the flow from the downstream duct will be reduced due to this sharp turn.
You can also create a more efficient connection using a HETO (Heavy-Duty Duct Outlet). These are rectangular taps that have a flat side to mount on the duct and a tapered opening on one end. Unlike other types of taps that require you to cut the duct, HETO’s are factory pre-cut and welded to the duct.
Rectangular Takeoffs
A rectangular takeoff has a flat facing that mounts to the ductwork, and it has a tapered opening on one end. It’s used to tap into a rectangular trunk line ductwork and it’s premise is that more volume can be captured by extending the rectangular ductwork’s longer two dimensions.
These aren’t as common as round to round takeoffs. They are more expensive because they have to be fabricated in the field by a sheet metal contractor, which is harder to do than making a standard coil line piece of duct. However, they are a better choice for high pressure ductwork because they don’t have the same airflow penalty as the traditional round to round takeoffs.
Directional takeoffs are designed with some form of scoop or extractor fitting (turning vanes that protrude into the airstream) that allows the duct to grab the air and direct it. While these work fine on the first branch duct they are connected to, airflow suffers down the line. It’s like blocking off a lane of traffic all at once—it takes time for traffic to get moving again.
It’s important to understand that taking an accurate duct takeoff involves much more than seeing how the duct can fit on the drawings. It’s about matching the physics of the equipment location and capability with proper duct sizing, a quality installation, and all the supporting materials and accessories needed to make the system come together as a functioning whole.
HETO Takeoffs
A heo takeoff is similar to the traditional duct tap, but it is designed for air flow efficiency. It has a larger duct opening and a gasketed flange that is often accompanied by a balancing damper. This makes it easier for the air to flow through the duct and eliminates hot spots and drafts.
These heos also have dimples that make it easy to find the mounting fasteners. They are usually made of 26 gauge galvanized steel, and they can be fabricated to fit a variety of diameters. HETOs can be used in round or rectangular duct systems and provide improved performance over standard duct taps.
HETOs are a must-have for every sheet metal worker, and they are typically included in the air distribution package by Bid & Spec companies that provide a full Air Distribution system. Since they are the first point of entry in a Branch Duct, they need to be strong and durable. A HETO that isn’t properly sealed or has a loose dial adjustment can cause the whole system to fail.
Choosing the right heo is essential to your HVAC job, and there are many options out there. You should always choose a high-quality product that has a solid damper blade, and make sure it is a sturdy construction. This can help ensure your heo isn’t damaged during installation and lasts for the life of your project.
Directional Tees & Extractor
This bi-directional extractor is designed for use with butane, or a 70% butane 30% propane blend. It can be purchased as a parts kit or preassembled. It is our smallest and most affordable bi-directional extractor.
Our tee extractor kits include a stainless steel carrying case with tee extractor, special ratchet, UNIDRILL Automatic 42 and cam pincer. Each nickel-plated tee extractor bell sits with a double vee block for accurate positioning producing precision 90 degree branches every time. Just drill the pilot hole, introduce the tee extractor hook into the drilled hole and screw the bell firmly to the tube wall. The tee extractor hooks have standard specification overlaps and optimum capillary gaps to ensure safe extractions, even with thicker tubes.
The tee extractor bases are typically jacketed to protect the base from heat damage, and can be placed in a pool of warm water for easier extractions. For safety, it is recommended to do all extractions outdoors and away from ignition hazards. Our tee extractors are also available in a wide variety of sizes, with and without handles. The base with handles is ideal for situations where the tee will be connected to a multi-legged component, such as an elbow or tee, and allows you to lift it by its handle rather than its valves. This helps to avoid accidentally loosening a threaded fitting when lifting it out of the water.