HVAC takeoffs are one of the most important parts of any HVAC system. They allow for the air to flow through a duct without allowing air to escape. There are several different types of takeoffs. The most common are round takeoffs, which are made from sheet metal pipe. Other types of takeoffs include the traditional tap-in side collar and the sheet metal elbow. These types all feature the same size opening that is mounted to the duct.
A HETO (High-Efficiency Takeoff) is a standard HVAC takeoff that taps into Rectangular Trunk Lines (RTLs). Traditionally, HETOs have been associated with Flat Duct. However, the use of oval pipe and large diameter round spirals as main trunk lines has changed the standard saddle tap.
The initial metal sheet is typically square or rectangular. After the initial drawing, the HETO begins to take shape. The side elevations of the HETO are shown in FIGS. 3D, 3E, 3F, and 3G. The latter shows the HETO from the leading side.
The HETO connector is manufactured by drawing, stamping, and trimming processes. The first drawing step involves defining the first body portion. This portion is extended from a rectangular air inlet or a circular panel. The second drawing step involves providing a bow-shaped leading edge at the top of the flange. The HETO connector is then molded over the duct using a special process.
Another type of HVAC takeoff is the High-efficiency Takeoff (HETO). This type of HVAC takeoff is designed for easy airflow entry through an oversized duct opening. It also often features a gasketed flange and a sealed connection. In addition, this type of takeoff often has a pre-installed balancing damper. These takeoffs cost more, but they provide superior airflow performance.
Rectangular HVAC takeoffs have several advantages over other tap styles. They have a flat facing and a tapered opening on one end, which allows them to capture more volume in a smaller space. For these reasons, they are often the preferred choice for commercial applications. Below are some examples of jobs where you may want to use a rectangular takeoff.
A takeoff should start and end at the match line. Then, a break should be drawn, which could be the SFD (Smoke Fire Damper). When drawing the takeoff, make sure to separate the High Supply Air portion from the Low Supply Air portion. The hatched-out portion belongs to another drawing. A takeoff should be directional with arrows to indicate the direction of the takeoff.
Another use for a takeoff is to change the direction of air flow. A rectangular takeoff can be fitted onto a round duct. It has a flat side to mount into and a round end to connect to a round snaplock pipe or Flex Duct. It can also be used in a round-to-round transition.
Rectangular takeoffs are a popular choice for branch HVAC installations. They feature larger openings than branch ducts and provide more flexibility to transfer air. If you are installing a duct system, you should choose a takeoff that will accommodate all the air flow you need.
Round branch ducts
HVAC takeoffs typically come in a variety of different shapes and sizes. A round branch duct has a smaller opening and a wider side opening than a square or rectangular branch duct. This type of HVAC takeoff is the most popular, and can be made of a variety of materials.
Round branch ducts can be made by using full body fittings or a saddle-tap. A saddle-tap connection requires a hole in the branch duct large enough to fit the outlet. This fitting is then secured with sheet metal screws and airtight. Once the branch is secured, the fitting process can begin.
The diameter of a round branch duct will vary depending on the amount of ducting used. A 20-foot diameter duct has a greater effective length than a two-foot diameter branch duct. The diameter of a round branch duct should be chosen carefully, as a smaller diameter duct will need more air to provide the same air flow.
A rectangular branch duct will require more metal for construction, which will add to its overall cost. In addition, it has a larger perimeter, resulting in increased air contact and friction. This increases the operating costs of a unit because the fan will have to work harder to move the air through it.
The SMACNA standard for HVAC takeoff includes a table that illustrates the minimum and maximum diameter of each type of HVAC takeoff. A spiral seam will also allow for lighter gages. For example, a round branch duct of 16 to 24 inches can use a 26-ga metal gauge. In contrast, a longitudinal seam of the same length will require an 18-gauge metal gage.
Double takeoffs are rectangular ducts or plenums cut in half to connect two different sizes of pipe. These tools make transitions from square duct to round pipe easier. Available in sizes from six inches wide by twelve inches long, these tools are durable and made from 26-gauge galvanized sheet metal.
HVAC takeoff software has many benefits for contractors, and autofitting generation is a valuable feature. Accurate takeoffs require a wealth of knowledge about materials, specs, labor rates, and other factors. By incorporating these features into a software program, HVAC contractors can save time and money while improving their bottom line.