Round ducts are generally preferred. The reason we use rectangular is 1) cost, 2) ceiling space. Oval duct is nice alternative to rectangular. The flow is better and you can change the aspect ratio to 'flatten' the duct to fit in the ceiling Equivalent diameter for rectangular and circular ducts - air flows between 100 - 50000 cfm The equivalent diameter is the diameter of a circular duct or pipe that gives the same pressure loss as an equivalent rectangular duct or pipe. The table below can be used to compare equivalent diameters for rectangular and round circular ducts SPIRAL DUCT. Spiral, or round, duct is typically fabricated from stainless steel, galvanized steel or aluminum rolls, and in some cases fiberglass board. The duct is commonly cut to 20 feet for shipping standards but can be cut to different sizes upon request
Technically round duct is going to be most efficient, but not if you have to undersize it or smash it to get it into its space. Think of it as a water hose, I would prefer a round hose over a rectangular because the water will flow better in the round, same goes for air The circular pattern of the round ducts allows for air to naturally flow through the duct. In a rectangular duct the flat surfaces cause airflow collisions that in turn create turbulence in the duct, thus causing an inefficiency in the duct's airflow
For example, a 12-by-12 rectangular duct has a perimeter of 48 inches. In comparison, the equivalent diameter round duct is 13.1 inches, which has a perimeter of only 41 inches — about a 15 percent reduction. This reduction in surface area results in less energy lost due to friction Rectangular ducts aren't as efficient with their airflow, which means they can create more harm than good in a high-pressure system. On the other hand, systems with round ducts can optimize airflow for reduced energy costs along with extended furnace and AC unit lifespans .30 [(ab)0.625/(a+b)0.250] a = length of one side of rectangular duct (inch) b = length of adjacent side of rectangular duct (inch) De= circular equivalent of rectangular duct for equal friction and capacity (inch) Source: 2001 ASHRAE Fundamentals, p. 32.1 R ound duct, which has lower and better pressure drop characteristics that reduce fan speed, is also more rigid than rectangular duct. This reduces the drum effect from duct vibration in comparison to a rectangular duct, which can transmit excessive noise if not properly supported. Insulation
In Figure 2, pressure losses through a round duct (D=0.5 m, v=5m/s, _=0.15mm) with rectangular ducts are compared with the same cross section area and flow rate. Obviously, the pressure drop through a round duct can be significantly less than the rectangular one. 0.5 1.5 2.5 02 4 6 8 1012 14 Aspect ratio Relative pressure loss based on round duct One thing they found is that the straight duct itself moves less air than the same size round duct. They compared a 6 round duct to two forms of oval duct made from a 6 round: 3 x 7.71 and 3.25 x 7.57. Their measurements showed that those two sizes of oval duct are equivalent to round duct at 5.02 and 5.18, respectively This week's podcast discussses round vs flat oval ductwork Our high pressure spiral duct, round ductwork, and flat oval duct — in comparison to traditional rectangular duct — is ideal for a number of different applications in a variety of industries, including construction, manufacturing, agriculture, mining, and restaurants
Chapter #2 - Round Ductwork and Fittings. In order to do a takeoff, you will need to be able to understand what rectangular duct and fittings look like and how they are represented on the drawings. Round fitting types and methods of construction can vary by region and between companies. Engineers use software programs that have standardized. 1-16 of 353 results for rectangular to round duct Price and other details may vary based on size and color. Elbow Bend PVC Adaptor 4.3 to 2.16'' to 4 inch Rectangular to Round 90 Degree Bend Adapter for Converting to Different Size Plastic Ducting Systems. $8.20 $ 8. 20. Get it as soon as Tue, Jul 27 The general consensus is that a round duct is more efficient and cost-effective than a rectangular duct. Air systems with round ducts have less air resistance because they use significantly less metal than rectangular duct systems. This also means that round duct is the cheaper option
An 18 in dia round duct, for example, has the same air-carrying capacity as a 26 in wide and 11 in high rectangular duct. The round duct has a cross-sectional area 254.5 sqin and a perimeter of 4.7 ft, while the rectangular duct has 286 sqin area and a perimeter of 6.2 ft Round duct performs with a lower pressure drop than rectangular duct. It is also more rigid, which keeps the drum effect from duct vibration lower compared to a rectangular duct. The noise level in rectangular ducts can be excessive if they are improperly supported The point of having a duct is to convey air from the air handling apparatus to the space to be conditioned. In order to fulfill this function in a practical way, we need to design the system within the prescribed limits of space, friction loss, ve.. A. Duct types 1. Round 2. Flat oval 3. Rectangular 4. Other: semi/quarter round, triangular Exposed Ductwork B. Elbow types 1. Pressed 2. Pleated 3. Gored C. Divided flow fittings 1. Straight tee 2. Conical tee 3. LoLoss™ tee Good, Better, & Best Duct Design - An Overvie
Example of big metal round and rectangular ducts (3,000+ CFM airflow). To figure out exactly how big ducts you need for central air conditioning systems, we have prepared complete CFM duct charts for all different kinds of ducts:. Duct sizing chart for flex ducts (round ducts with 5-20 inch diameter).; Duct sizing chart for metal ducts (round ducts with 5-20 inch diameter) Rectangular to Round Conversion De = 1.30 [(ab)0.625/(a+b)0.250] a = length of one side of rectangular duct (inch) b = length of adjacent side of rectangular duct (inch) De= circular equivalent of rectangular duct for equal friction and capacity (inch) Source: 2001 ASHRAE Fundamentals, p. 32.1 Flex duct = .05 on most metal duct calculator Round metal pipe = .06 on most metal duct calculators FIELD DUCT SIZING CHART Rectangular sheet metal duct = .07 on most metal duct calculator A/C is currently in the attic, and services the main floor via round ducts. As the thread title shows, my question is: does it matter if you use round or rectangular vents for a furnace or a heat pump? I'm pretty sure we want to go with a gas furnace (we have natural gas currently for other items in the house, including the inoperable boiler)..
Oval duct sizes are not quite the same as rectangular and round sizes. 3-1/2 x 10, if I remember correctly, is what they call 7 oval. This would seem to imply that it is the equivalent of a 7 round duct, but in fact it is more like the equivalent of 6.5 round, if there were such a thing Always stagger take-off ducts by 12 to maintain pressure. Use insulated duct or duct board in unheated spaces. Flexible duct work must be stretched tightly for maximum air flow. Information provided is to be used as a guideline only. Rectangular and Round Duct Rectangular Duct Height (inches The equivalent diameter is the diameter of a circular duct or pipe that for equal flow gives the same pressure loss or resistance as an equivalent rectangular duct or pipe. A round shape results in lower pressure drops and less fan horsepower to move the air and, consequently, smaller equipment
Spiral Round Duct. Spiral round lock-seam duct is the most efficient way to transport air in HVAC systems. The round profile greater flow efficiencies than rectangular ducts. Because round ducts are inherently stronger than rectangular profiles, they can be lighter metal gauges and can be installed in longer spans Transitions, e.g. from rectangular baghouse apertures to round ducts, are a little harder to manufacture than simple joints. They're harder to draw, too, which may be the real reason rectangular flue ducts first appeared. Mike Halloran Pembroke Pines, FL, US
For round branch ducts, these rectangular-to-round fittings allowed easy air entry due to a substantially oversized duct opening. When working with rectangular branch ducts, such as those found in commercial applications, a 45-degree rectangular transition fitting that has a 30-40 percent larger opening creates a smooth pathway for air to move. Rectangular vs Round Duct Dimensions I'm trying to create a single parameter that will read the largest duct dimension (regardless of rectangular or round) in a duct schedule. Basically: Find the Greatest of Length, Width and Diameter, where some ducts have two of the three and some only have one Flexible HVAC Ductwork. This type of ductwork is usually tube shaped and is made from a wire coil covered in a bendable but durable plastic. Manufacturers then cover the tube in fiberglass insulation. Using this kind of ducting is best in tricky spaces where rigid ducts are not just possible to install vs. rectangular. Lower fan power • General air duct sizing calculators show round having up to 45% lower airflow resistance - Recycled and recyclable metal • Survivability of internal grease fires • Easier to clean - Grease won't stick to round stainless as easy - Spin-jet heads will work better in round Round duct has less surface area, weight and fewer joints than rectangular duct. It is much easier to seal and can easily be specified to meet SMACNA Class 3 Leakage even at 10 in. wg static pressures. Flat Oval is the next most efficient shape and the closer the aspect ratio approaches 1, the more it approaches the efficiency of round duct. An.
Studies have shown that round duct produces less airflow resistance than rectangular duct, which lowers energy use. With the seam entirely on the outside of the duct, spiral duct also has a smooth interior that minimizes friction losses. Another key airflow issue concerns pressure. Air leaving an air handler under high pressure drops to lower. There are very few disadvantages to oval ductwork being used in the home. It might cost you a little more to transition from rectangular ductwork to new oval ducts. You might also need to choose between flat oval ducts versus round ducts, though talking to your local duct provider should make this an easier decision Round vs. Rectangular Ducts February 24, 2021 6:08 pm Published by Writer Leave your thoughts. More differences exist between round and rectangular air ducts than you might think. Choosing one type over the other can make or break the effectiveness of your home's HVAC system, so it's important to know the facts before undergoing such a big.
Laboratory Duct Construction. Ductwork systems serving laboratory or cleanroom applications have unique construction requirements that must be addressed by the design engineer. Most laboratories are usually put in the general category of chemical laboratories; however, there are many subclasses in this category, and other types of laboratories (e.g. radiological and biological) exist as well My current problem is that using Fabrication Ductwork in Revit, the rectangular taps DO connect to the rectangular duct, but the round taps DO NOT connect for some reason. Even though they look correct and convert fine when using Design to Fabrication, only the square duct taps stay attached to the duct mains; the round taps just kind of. Rectangular Ductwork, Plenums, and Takeoffs Select from the menu below to view any of our product lines. --- Select a Product Line --- Round Pipe and Pipe Fittings Collars for Sheetmetal Collars for Ductboard Boots and Boxes Rectangular Ductwork, Plenums, and Takeoffs Wall Stack & Wall Stack Fittings Oval Pipe & Oval Fittings Mobile & Modular. notes: 1. tdc duct constructed per smacna standards-first edition 1995 2. duct fabricated using pittsburg seams. 3. all duct stiffened by machine formed beads spaced at 12 o.c. 4. duct work to be sealed per smacna hvac table 1-2 5. tdc cnt-jnt-condu-loc @ tdc connector center of duct & @ tdc connecto
Slim Duct. Slim duct, sometimes called periscope duct or known by the brands Tite-Fit or Skinny Duct, is a telescoping rigid aluminum duct designed for transition ducting in tight spaces. It has a wide rectangular shape except for the two ends where it connects to the dryer and the vent outlet Oval Ductwork Pipe (22) Rectangular Ductwork Pipe (119) Round Ductwork Pipe (164) Spiral Ductwork Pipe (13) When making a selection below to narrow your results down, each selection made will reload the page to display the desired results. 4 inch (18) 5 inch (15) 6 inch (23) 7 inch (20 Duct Square-To-Round. Sort. Show List View $ Royal Metal Products 8 x 4 x 4 in. Flange Insert Box with Gasket. Part # R525R6G844. Item # 4221286. Mfr. Part # 525R6G844. X. POINTS. To see availability for this product, personLog In or Get Online Access. Call for Pricing $ Royal Metal Products 10 x 10 in. Flange Insert Box with Gasket. Rectangular Duct and Fittings. Often used in tight spaces, such as in walls and ceilings, rectangular duct allows you to select larger sizes without increasing duct height. Duct and fittings have interconnecting ends that lock together with brackets. For technical drawings and 3-D models, click on a part number
The fourth edition of HVAC Systems Duct Design presents the basic methods and procedures required to design HVAC air distribution systems. This manual provides the HVAC system designer detailed information on duct design and U.S. and metric units are provided in all examples, calculations, and tables. Testing, Adjusting and Balancing (TAB) RECTANGULAR DUCT & FITTINGS VERTICAL ELBOW - 90 ROUND INNER RADIUS. ROUND INNER RADIUS. Page Loading... Narrow Results By: Sort By: 1 - 8 of 8 Items . Show Grid | Show List. Items per page. Page 1 of 1 View Cart Checkout. 8 X 8 VERT ELBOW  8 X 8 VERT ELBOW . 4 Round Sheet Metal Duct End Cap. Sheet Metal Duct End Caps are the perfect sheet metal duct fitting to use when you terminate a duct run. All End Caps are manufactured from the highest of quality galvanized steel. They are perfect for maintaining a professional look, especially if your..
Duct Hanger, Round, 14 In, 20 Gauge Steel. Item # 6PGA2. Mfr. Model # GRRDH14GA20. UNSPSC # 40141725. Catalog Page # N/A. Country of Origin USA. Country of Origin is subject to change. Duct Hangers. Vibration Isolating Hanger is a steel suspension bracket with a rubber isolation pad to prevent noise transmission If this were a straight duct the critical issue would be the increase in friction of a rectangular vs a round duct. But its not a straight duct; it has elbows and who knows what other fittings. You will need to calculate the increase in equivalent duct length and see if the system can tolerate it and if increasing the duct size would be necessary
Would it be ok to tap off the main with rectangular take offs, adapt to round, then route insulated flexible round ducting to the base of the walls (to meet the risers), as long as both the round connector duct and rectangular ducts (in the walls) are of the same cfm load (e.g. 6 round ~= 3x10 rect) system. A duct system is a network of round or rectangular tubes—generally constructed of sheet metal, fiberglass board, or a flexible plasticand- wire composite—located within the walls, floors, and ceilings. Usually, you can see only the outlet, which is a register covered with grillwork
Most of the duct friction charts that are out there are based on round ducts. That means that if you are working with a rectangular duct or a flat oval duct, you will need to come up with the equivalent circular duct size if you are using some other cross sectional shape, like rectangular duct or flat oval duct The basic principle is to transform the round cross section of the duct into a slim rectangular one while maintaining the area of the cross-section because my intuition told me that reducing the duct size will make my a/c less efficient (and ultimately perhaps even damage it) For duct sides greater than 36 inches, 7 points must be taken. Multiply the numbers in the table times the duct dimension to get insertion depth for the probe. 0.061 H 0.235 H 0.437 H 0.563 H 0.765 H 0.939 H H 0.074 V 0.288 V 0.500 V 0.712 V 0.926 V V Figure 2: Location of measuring points for traversing a rectangular duct using log-Tchebycheff. Information Required for Duct Construction 1. A comprehensive duct layout indicating sizes, design airflows, pressure class, and routing of the duct system. 2. The types of fittings to be used based on the designer's calculations of fitting losses (i.e., square versus 45 ° entry taps, conical versus straight taps, etc.)
Assuming that the skylight top structure has an opening that is matched by the ceiling opening and the connecting duct (for example 500mm diameter all the way through for a round or 500x500mm dimensions all the way through for a square), the following factors then need to be taken into account: 800x500mm rectangular. 0.400. 1100x500mm. Velocity Duct Sizing Chart Residential Main Supply Trunk Ducts, Non-zoned systems (target velocity of 800FPM used) Listed by air quantity, round duct size and nearest square duct size 500CFM 11Ø or 10 X 10 1,300CFM 16Ø or 14 X 16 600CFM 12Ø or 10 X 12 1,400CFM 18Ø or 16 X 1 Table 1 - Duct Size vs. Airflow at a Friction Rate of 0.1. Table 1 is an example of the airflow that you would get from various size vinyl flex ducts in a system with a friction rate of 0.1 iwc/100'. Now, I'm taking a huge risk by putting this table out there and I will probably get a lot of grief for it, but here it is 6 in. x 5 ft. Round Metal Duct Pipe Master Flow Metal Pipe is available in a Master Flow Metal Pipe is available in a variety of common lengths, diameters and gauges to help make your next HVAC project a success. Round pipe can be used as a main trunk line or branch line, as well as in return air situations
Replacing subfloor in bedroom. Have a 5 supply duct, about 5' run to the register, in a 2x8 floor joist bay. However that is in the way of some bracing and blocking I need to do as the new subfloor has an unsupported edge. So I was thinking about replacing the 5 round with a 3 1/4x10 rectangular duct Sheet Metal Duct Friction Loss Calculator. 1. Enter Duct Airflow (CFM), Duct Velocity (FPM), Duct Length and the number of bends. 2. Read Round Duct Diameter (inches) and Friction Loss Per 100' of duct (inches of water)
Round duct vs. rectangular duct. Round ductwork is ideal for directing the air that has a low-pressure drop. It also produces less noise, which can be a nuisance to the occupants of the room. Lastly, its installation cost is far less than that of rectangular ductwork L profile rectangular duct is the half cross-section of a rectangular duct when it is separated diagonally. It becomes easier to transport the L profile rectangular duct and assemble at site. 21. Is Round Duct better than Rectangular Ductwork? Yes, round duct work is more efficient in comparison to rectangular ductwork in performing the same. Spiral & Round Seamed Ductwork. Round ductwork where used has advantages of faster installation, lower costs, lower leakages, lower pressure drops and better operations. Spiral wound ductwork and fittings made to known industry standards are exceeding used on large scale projects for their particularly low leakages and self-sealing mechanisms Round. The area of round flex ducts is calculated as π*R 2 where R is the radius of the duct. Example: 10-inch round duct has a radius of 5 inches. Its cross-section is calculated as 3.14*5 2 = 78.5 sq inches or 0.545 sq ft. Rectangular. The area of rectangular ducts is calculated as x*y where x and y and the length of the sides of the ducts Rectangular Single Wall Duct & Fittings Sheet Metal Connectors, Inc. (SMC) TDC, Slip/Drive and Raw Sheet Metal Connectors, Inc. rectangular duct and fittings are one part of our complete line of HVAC products. SMC manufactures coil line ductwork in 4'-5'-6' lengths. All ductwork comes standard with stiffening beads
friction loss per L feet of duct in terms of total pressure, iwg Dh density, lbm/ft3 D Number of conduits Conduits for equal friction Duct Diameter Number of Conduits @ equal velocity Round Flat Oval Rectangular De = 1.3 x ((a x b)0.625) / ((a + b)0.250) Rectangular to Round De = 1.55 x ((A)0.625)/((P)0.250) Flat Oval to Round CFM /Each. The job contract was for over $1.2 million in ductwork- mostly heavy gauge, from 6-in. to a 96-in. round 10-gauge stainless header SS316, for the large exhaust system. Contact Info 2600 Airline Boulevard, Portsmouth, VA 2370 Rectangular dampers are designed to hold duct dimensions when mounted inside rectangular duct using extruded aluminum frame and mitered corners with L brackets. The damper is available in power open/power close, power open/close/modulating, power close/spring open, and power open/spring close Converts a rectangular size to the appropriate round size or the available ESM flat oval size. * Indicates Required Field Rectangular Width The following tests of rectangular duct sections and transverse joints were conducted in accordance with Section VII of the SMACNA HVAC Duct Construction Standards, 2nd ed., 1995. Certified copies of these tests are available upon request
Figure 8.1(b) Formation of Secondary Flow in a Bend of a Duct Figure 8.1(b) shows one example of the formation of a secondary flow in a gently-curving duct of rectangular cross-section. The curvature of the flow is accompanied by a pressure gradient which rises across the section from the inner to the outer wall Available for both round and oval duct, flanges fit inside the ductwork and are screwed or tack welded to the spiral itself, with a butyl gasket providing the seal. Double wall can be handled the same way, with the flange engineered to have two rings, allowing various thicknesses of liner to go in between rectangular duct order sheet ® 9 Fab-Tech, Inc. / 480 Hercules Drive, Colchester, VT 05446 / Tel: 802-655-8800 / Fax: 802-655-8804 / www.fabtechinc.co Round and oval duct have lower initial installed costs than rectangular duct. Their shape results in lower pressure drops, thereby requiring less fan horsepower to move the air and, consequently, smaller equipment. The shape also has less surface area and requires less insulation when externally wrapped. Spiral round and oval duct