Enter the air flowrate in litres/second (can change to cubic metres/second by use of drop-down to the right of the input) Enter an internal duct diameter (this can be any number, it doesn’t need to be standard duct size) To get an idea of the equivalent rectangular duct size, adjust the aspect ratio. Note that only aspect ratio up to 5:1 are ... Air Duct Calculator -Slide Rule Style. This rectangular air duct calculator is the technicians favorite. Provides the following information with one setting:- Friction- Velocity- Round Duct Size- Surface Area...and more. Size: 4" x 8.5". ISBN No. 9781622709823Sturdy construction of heavyweight calculator board with 6 metal eyelets. Purchase ADI Ductulator. The ADI - Air Distribution Institute, was formed in 1947 to promote the use of fabricated steel duct pipe and fittings for air distribution products. Today the alliance of ADI member companies produce steel duct pipe and fittings designed to efficiently deliver conditioned air in your home and office. The smallest return air grille is usually starts at 4 inches by 4 inches. So, the next corresponding return air grille size includes 4×6, 6×6, 6×4, 8×6, 4×8 and so on. The largest return air grille is typically stops at 48 inches by 24 inches. Here are some examples of a standard return air grille: 4×4. 6×6.Volume is the cross-sectional area multiplied by the length of the duct.; Density is the density of the material the duct is made of.; Diameter is the diameter of the round or spiral duct.; Width and Height are the dimensions of rectangular, oval, or flat oval ducts.; Length is the length of the duct.; For insulated ducts, you calculate the weight …Nov 11, 2023 · The Duct Area Calculator is a powerful tool designed to help individuals and professionals in the HVAC industry determine the cross-sectional area of rectangular and circular ducts. This essential calculation aids in optimizing airflow, ensuring efficient ventilation systems, and maintaining optimal indoor air quality. All Duct Calculator. An inclusive air duct calculator for diameter, velocity, CFM, and pressure drop of various types of duct. It will also determine round duct equivalents for rectangle, flat oval, and elliptical (flattened round) duct. Duct roughness and air properties are adjustable and includes a metric option. Open Calculator. Air Flow Conversion Calculator. CUI Devices' air flow conversion calculator can be used to convert between common units for volume air flow and air velocity flowing past a point in a specified area of duct. To use the calculator, enter your air velocity or volume air flow and duct area/type, select your units, click calculate air flow, and your ...Air Flow Conversion Calculator. CUI Devices' air flow conversion calculator can be used to convert between common units for volume air flow and air velocity flowing past a point in a specified area of duct. To use the calculator, enter your air velocity or volume air flow and duct area/type, select your units, click calculate air flow, and your ... Rectangular duct is rounded up to the nearest 1/4 inch. Calculations are for 60°F dry air at sea level, from 5 to 3000 cfm (approximately standard air which is 0.075lb da /ft³). If "ASHRAE 2013" is selected, Flexible roughness is 0.003 ft when straight and fully stretched tight at 0% compression (adjusted at other compressions), otherwise the ... Duct and vent cleaning costs $25 to $45 per vent or $0.15 to $0.25 per square foot. Air duct sanitizing costs $70 to $150 more to prevent mold growth. An air duct inspection costs $80 to $180. Cleaning the HVAC system costs $60 to $370 more for a furnace or AC unit. Air duct cleaning cost - chart.Check this out: air ducts - or HVAC ductwork, or AC ducts - are conduits that supply warm or cool air to heat, ventilate, and cool each room in a house. Air ducts are connected to the HVAC unit, which filters and heats / cools your home’s air before sending it off. Air ducts are a vital part of your HVAC system, providing thermal well-being ...Mar 4, 2023 · Duct Sizing Calculator. The duct sizing calculation involves determining the proper ductwork size needed for an HVAC system. The formula used in this calculation is Q=VA, where Q is the airflow rate, V is the air velocity, and A is the area of the duct. Imperial Equation. Determine the following formula, which can be used to calculate the air duct velocity: V = 0.408 Q/D 2. Components. = Air velocity inside the duct (feet/s) = Air … Enter the air flowrate in litres/second (can change to cubic metres/second by use of drop-down to the right of the input) Enter an internal duct diameter (this can be any number, it doesn’t need to be standard duct size) To get an idea of the equivalent rectangular duct size, adjust the aspect ratio. Note that only aspect ratio up to 5:1 are ... 50°F (27.8°C) 2″ (50mm) Recommended Duct Insulation Thickness for Concealed Ducts. So, if my dew point is 77°F (25°C) and the supply air temperature is 59°F (15°C), the temperature difference is 18°F (10°C) which is below 30°F (16.7°C). Therefore, my duct insulation should be 1″ (25mm) thick.Air duct pressure loss. Friction loss calculation is made in rectangular or round ventilation ducts. Fill in the form below. Unit system. : Duct type. : Duct position.The Duct Area Calculator is a powerful tool designed to help individuals and professionals in the HVAC industry determine the cross-sectional area of rectangular and circular ducts. This essential calculation aids in optimizing airflow, ensuring efficient ventilation systems, and maintaining optimal indoor air quality.Free HVAC Duct Sizing - in SI/Metric or US/Imperial units. Welcome to CalcuDUCT - the quick and easy way to size ducts for any HVAC application.AIR DUCT CALCULATOR : by Michael J. Rocchetti PE Mechanical Engineer . Metric Units. Flow rate M^3/S: Velocity M/S: Pressure Pascals: Temperature C: Length Meter: Duct Material: Uncoated Carbon Steel: PVC Plastic Pipe (smooth) Aluminum (smooth) galvanized steel (medium smooth) galvanized steel (average smooth) fiberglass duct …DUCTULATOR. Sizing air ducts is essential task for HVAC Engineers, it requires quick tool to aid HVAC designer to determine air duct dimensions while drafting AC layouts. DUCTULATOR Software, uses two methods to size air ducts based on velocity or static regain method, taking into account the air properties at given temperature and elevation ...The Ultimate HVAC Duct Calculator Guide: Increase Efficiency and Improve Airflow. HVAC duct calculators play an essential role in determining the proper size of ductwork for heating, ventilation, and air conditioning systems. Properly sized ducts are critical to maintaining optimum airflow, improving energy efficiency, and ensuring the …HVAC Charts - Your Source for Heating & Air Conditioning Charts and Supplies. Duct Sizing Calculator. The Duct Sizing Calculator is a hand held sliding calculator used for sizing supply and return duct systems using the equal friction, or velocity reduction design method. Front of calculator includes scales for friction, velocity, round duct ...AllDuctCalc™ - HVAC Air Duct Calculator v2 Updated 10/26/15: Provide inputs in the blue boxes, other inputs optional.Step-3 Calculate Fresh Air Considering People outdoor air rate & Area area outdoor air rate as per ASHRAE 62.1: ... Normally, fresh air duct is not insulated, however, if there is a chance of heat gain from outside or there is any heat source near to that duct, insulation can be considered.Air duct pressure loss. Friction loss calculation is made in rectangular or round ventilation ducts. Fill in the form below. Unit system. : Duct type. : Duct position.Enter the air volume in CFM [l/s]. Select an input criteria and enter its value. Optional: Enter a constraining rectangular duct dimension in inches [cm] Click the Calculate button. …Duct Calculator Elite https://apps.apple.com/us/app/duct-calculator-elite/id665701601Air flow rates: information is provided on recommended air flow rates for each duct size. These flow rates are related to the volume of air needed for the HVAC system to maintain thermal comfort and air quality. Air speed: the graph illustrates the air speeds that can be obtained for the different dimensions of the ducts and air flow rates.Jul 29, 2022 · Return air duct size for 1-5 ton ACs is 14” to 22” for round ducts and 13”x12” to 32”x12” for rectangular ducts. Use the return air duct size calculator below for accurate dimensions required for your air conditioner or heat pump. There is also a table of return air duct sizes for round and rectangular ducts for ACs from 1.5 to 5 tons. Ductulator - Hand held rotating calculator used for sizing supply and return duct systems using the equal friction design method. Includes scales for friction loss per unit length, air volume, air velocity, round duct diameter, and rectangular duct diameters. One side uses English units, the other side uses Metric units. The pressure losses in ducts are caused by friction between the air and the duct surfaces, as well as by fittings and bends in the duct system. How do you calculate CFM from pressure drop? CFM (Cubic Feet per Minute) can be calculated from pressure drop using the fan laws, which relate CFM, pressure, and fan performance.Example - Calculate Reynolds Number. A Newtonian fluid with a dynamic or absolute viscosity of 0.38 Ns/m 2 and a specific gravity of 0.91 flows through a 25 mm diameter pipe with a velocity of 2.6 m/s .. Density can be calculated from the specific gravity of the fluid and the density of the specific gravity reference water 1000 kg/m 3 - as. ρ = 0.91 (1000 …The equivalent diameter of a rectangular tube or duct can be calculated as (Huebscher) de = 1.30 (a b)0.625/ (a + b)0.25(1) where. de = equivalent diameter (mm, inches) a= length of major or minor side (mm, inches) b= length of minor or major side (mm, inches) Hydraulic diameter - the "characteristic length" used to calculate the dimensionless ...Duct-U-Lator. This app works as a Ductulator and Pressure Loss (friction) calculator which has the following functions. Converts Duct Shape or Size to Another. Determines Sizes for a Given Friction Rate. Determines Sizes for a Given Velocity. Determines Sizes for a Given Velocity and a Friction Loss Rate (simultaneous output)An HVAC duct calculator or ductulator is a tool that can be used to calculate the ideal size of your HVAC ducts. It factors in the area size and temperature, air flow velocity, friction loss, and static pressure of the HVAC system.1. Diameter converter, which converts circular diameters to equivalent rectangular ducts. 2. Ventilation parameter calculator allows the diameter, air speed, airflow and dynamic pressure of your installation to be calculated. 3. Pressure drop calculation tool for installations with straight sections and duct system elements. 4.Air duct also termed as ductulator is a passage that is used to provide fresh air into rooms, buildings etc., Air ducts may be in circular, square and in rectangular shapes. This online air duct calculator is used to calculate the velocity of air flow feet per minute (FPM), and feet per second (FPS) through any shaped (circle, square or rectangle) ductulator with …PRODUCT DETAILS. AIR DUCT SLIDE RULE CALCULATOR. Size: 4"x9.25". Material: Heavyweight coated calculator board. Production: Each order is custom manufactured with your company information and in your choice of colors. AIR DUCT WIZARD DUCTULATORS. Size: 8.5"x11" card with a 7.25" wheel. Materials: Heavyweight coated …The chart below can be used to estimate velocities in air ducts. The default values are for air flow 400 cfm (680 m3 /h) , duct size 8 in (200 mm) and velocity 1150 fpm (5.8 m/s) . Download and print Air Ducts - Velocity …The ASHRAE Duct Fitting Database (DFDB) app allows you to perform pressure loss calculations for all 200+ ASHRAE duct fittings in both I-P and SI units. Use this mobile app in the field for quick duct pressure loss calculations. The inputs can be adjusted by touch, and installation is automatic. Available via iTunes®, the app is now universal ... TO CALCULATE DUCT SIZE: Enter Air Quantity (Flow Rate) Enter either Friction Loss or Velocity. The software will automatically detect the calculation method. Click Calculate and refer to duct size box for results. Click Refresh for a new calculation. V = 0.408 Q/D 2. Components. = Air velocity inside the duct (feet/s) = Air flow rate inside the duct (GPM) = Air flow rate inside the duct (inches) Metric Equation. Determine the following formula, which can be used to calculate the air duct velocity: V …Get free shipping on qualified Ducting & Venting products or Buy Online Pick Up in Store today in the ... resistant, 4-ply aluminum foil laminate that encapsulates a high density, corrosion resistant wire helix. This forms an air tight and easy to use air duct. View Product. Explore More on homedepot.com. Doors & Windows. 1 Panel 36 x 79 ...Air Duct Elbow Loss. Calculation of pressure loss in elbows on ventilation ducts. Fill in the form below. Wid. (W)/Heig. (H) Calculation of local losses in elbows in ventilation ducts.Undersized return air ducts result in the ducts and grills being more noisy than usual and the air conditioner components becoming stressed, thus reducing the lifetime of the unit. Use our handy return air duct size calculator or charts below to help you determine the correct return air vent size for your home.Now, we can use the previous equation to calculate the makeup air rate for kitchens and dryers under these conditions. (1) 400 – 190 = 210 CFM of makeup air (2) 200 – 190 = 10 CFM of makeup air. Makeup Air Duct Size. Below is a table of the average air inflow rates through different size ducts at different air pressures:At 350-400 CFM per 12,000 BTUs of heating capacity, there’s enough airflow to circulate heated air through supply ducts and pull cool air back to the furnace or air handler through the cold air returns. A 3-ton unit, or 36,000 BTUs, would need a blower capable of moving 3 x 350-400 CFM, so a total of 1,050 to 1,200 CFM.Calculation of pressure drops of flowing liquids and gases in pipes and pipe elements (laminar and turbulent flow). New version of Online Calculator is available: www.pressure-drop.online. Pressure Drop Software for Excel: Druckverlust Software …The velocity reduction method can be used when sizing air ducts. Equivalent Diameter - Rectangular vs. Circular HVAC Ducts Rectangular equivalent diameter for air flows between 100 - 50000 cfm. Fluid Flow - Equivalent Diameter Convert rectangular and oval duct geometry to a equivalent circular diameter - online calculator with imperial and SI ...Section 5 - Air Distribution System Design This section provides an executive overview of duct system design procedures, additionally covering the use of a branch take off fitting at the end of a supply air trunk duct. Section 6 - Duct Sizing Calculations This section covers the duct system design procedures in detail.A 4 feet air duct with diameter 2 inch and air flow volume 156 cfm has a friction loss of. = (0.109136 * 156 1.9 ) / (2 5.02) = 1.97603 inches. = (0.109136 * 156 1.9 ) / (2 5.02 )* (4/100) = 49.40069 inches / 100 feet. Air Ducts are passages for air to travel within your home. The loss in pressure of the flow that occurs due to the air ...Check this out: air ducts - or HVAC ductwork, or AC ducts - are conduits that supply warm or cool air to heat, ventilate, and cool each room in a house. Air ducts are connected to the HVAC unit, which filters and heats / cools your home’s air before sending it off. Air ducts are a vital part of your HVAC system, providing thermal well-being ...Best prices guaranteed. We match other Aussie retailers*. Use our sizing calculator below to determine the minimum size required for your room or house. Remember for ducted systems only include the air conditioned spaces, exclude areas like …JP Lamborn Co. ( JPL ) began producing flexible air ducts in 1961. Today the company operates four state-of-the-art manufacturing facilities and is the largest family-owned flexible air duct manufacturer in North America. JPL’s core values of manufacturing high-quality products, providing excellent service, innovation, and strong business ...Duct-U-Lator. This app works as a Ductulator and Pressure Loss (friction) calculator which has the following functions. Converts Duct Shape or Size to Another. Determines Sizes for a Given Friction Rate. Determines Sizes for a Given Velocity. Determines Sizes for a Given Velocity and a Friction Loss Rate (simultaneous output)Here’s some insight from this chart: To produce 1 CFM, we would need 11.46 FPM, 5.09 FPM, 2.86 FPM, and 1.83 FPM air velocity in 4-inch, 6-inch, 8-inch, and 10-inch round duct, respectively.We can clearly see that we need lower FPM per CFM the larger the duct we use. For 100 CFM, we need between 183.35 FPM and 1145.92 FPM, if we use 4-10 inch …Adjustable Absolute Duct Roughness. If selected, Flexible roughness is 0.003 ft when. straight and fully stretched tight at 0% compression. (adjusted at other compressions), otherwise the. original method of constant 0.01 ft roughness is used. Use ASH RAE 2013 Flex Compression.The equivalent diameter of a rectangular tube or duct can be calculated as (Huebscher) de = 1.30 (a b)0.625/ (a + b)0.25(1) where. de = equivalent diameter (mm, inches) a= length of major or minor side (mm, inches) b= length of minor or major side (mm, inches) Hydraulic diameter - the "characteristic length" used to calculate the dimensionless ...A major friction loss diagram for air ducts - Imperial units ranging 10 - 100 000 cfm. Air Ducts - Major Friction Head Loss, Online Calculator Head loss or major loss in air ducts - equations and online calculator for rectangular and circular ducts - Imperial and SI units. Air Ducts - Sizing Required duct area vs. air flow. Air Ducts - Velocity ...Air Duct Calculator/Ductulator with Sleeve. 4.2 out of 5 stars. 18. $15.60 $ 15. 60. FREE delivery Apr 29 - May 2 . Add to cart-Remove. Trane Ductulator and Charging Calculator Kit - Trane Flex Ductulator with Sleeve, Metal Ductulator, R-22 Charging Calculator, R410A Charging Calculator.Air Flow Conversion Calculator. CUI Devices' air flow conversion calculator can be used to convert between common units for volume air flow and air velocity flowing past a point in a specified area of duct. To use the calculator, enter your air velocity or volume air flow and duct area/type, select your units, click calculate air flow, and your ...An HVAC duct calculator or ductulator is a tool that can be used to calculate the ideal size of your HVAC ducts. It factors in the area size and temperature, air flow velocity, friction loss, and static pressure of the HVAC system.Now, to properly calculate the return grille size, we have to make these two assumptions: Face velocity is 500 FPM (feet per minute). This is the speed at which the return grille sucks the air from your house into your ducts. Free grille area is 70%. As we know, the grille is always bigger than the duct through which the airflow flows.A good HVAC duct sizing rule of thumb is to measure rooms in your home, the necessary airflow rates, and friction loss rate. Using these numbers you can calculate the appropriate HVAC duct size. For example, a one-to AC system typically uses 10-inch ducts, while a 4-ton AC system requires 18-inch ducts. There are several variables to …About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright ... Air Duct Calculator/Ductulator with Sleeve. 3.9 out of 5 stars 14. $14.70 $ 14. 70. FREE delivery Jun 30 - Jul 6 . Flexible Duct Friction Loss Calculator/Flex Duct ... Jul 29, 2022 · Return air duct size for 1-5 ton ACs is 14” to 22” for round ducts and 13”x12” to 32”x12” for rectangular ducts. Use the return air duct size calculator below for accurate dimensions required for your air conditioner or heat pump. There is also a table of return air duct sizes for round and rectangular ducts for ACs from 1.5 to 5 tons. Enter the air volume in CFM [l/s]. Select an input criteria and enter its value. Optional: Enter a constraining rectangular duct dimension in inches [cm] Click the Calculate button. …Now, to properly calculate the return grille size, we have to make these two assumptions: Face velocity is 500 FPM (feet per minute). This is the speed at which the return grille sucks the air from your house into your ducts. Free grille area is 70%. As we know, the grille is always bigger than the duct through which the airflow flows. Air Duct Calculator. Double-sided. Side 1 = standard ducloator with calculations for both round and rectangular duct. Side 2 = Continental vs competitive cross reference for some common GRDs and a Grille sizing chart. Qty 25/package. Enter 6" into the Duct Height (Optional) field. The results table show a 10"x6" duct. This calculator can also be used to simply convert round to rectangular or vice versa. It is unnecessary to consider the duct material, length, or air volume since it is just a physical, geometric calculation. Assume we have an 18" round duct.Nov 11, 2023 · The Duct Area Calculator is a powerful tool designed to help individuals and professionals in the HVAC industry determine the cross-sectional area of rectangular and circular ducts. This essential calculation aids in optimizing airflow, ensuring efficient ventilation systems, and maintaining optimal indoor air quality. Duct work attenuation. Calculate the attenuation in unlined and lined ducts. Note that the table and diagrams list the attenuation in dB/m. 13. ... The speed and attenuation of sound in moist air varies with sound frequency and air humidity. Sound Attenuation - …All Duct Calculator. An inclusive air duct calculator for diameter, velocity, CFM, and pressure drop of various types of duct. It will also determine round duct equivalents for rectangle, flat oval, and elliptical (flattened round) duct. Duct roughness and air properties are adjustable and includes a metric option. Open Calculator.The Duct Area Calculator is a powerful tool designed to help individuals and professionals in the HVAC industry determine the cross-sectional area of rectangular and circular ducts. This essential calculation aids in optimizing airflow, ensuring efficient ventilation systems, and maintaining optimal indoor air quality.Duct Sizer ( Ductulator) for HVAC air ducts. It is designed for calculating and sizing duct dimensions according to air volume CFM, roughness, velocity, etc. It is available in SI and British IP units. Duct sizing needs a ductulator or software but this excel calculator performs the same calculations. 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). 1. Enter Friction Loss Per 100' of duct (inches of water), Duct Airflow (CFM), Duct Length and the number of bends.
Feb 16, 2023 · Calculate for each individual room. To calculate CFM, you need to know the size of your heating or cooling unit in tons. Multiply this number by 400, which is the average output of an HVAC unit. Then divide by the total square footage of your home. This will give you the multiplier for all your rooms’ CFM. . Fif_i
Purchase ADI Ductulator. The ADI - Air Distribution Institute, was formed in 1947 to promote the use of fabricated steel duct pipe and fittings for air distribution products. Today the alliance of ADI member companies produce steel duct pipe and fittings designed to efficiently deliver conditioned air in your home and office. This tool will calculate the velocity in any units from the specified volumetric flow rate of a substance flowing through a rectangular duct of a defined width and height. For each new calculation a unique conversion scale will be generated for the range of volumetric flow rates and flow speeds for the length and width specified. FormulaCalculation of duct insulation. Easy program which, by entering a few values, immediately calculates the surface area of the ducts and insulation of the aeraulic circuit under consideration. Valid for quadrangular and circular ducts. In addition to the thickness of the insulation, it is possible to enter waste values (percentage of materials ...While air duct cleaning and repair lengthens its life span, ductwork typically needs major replacement every 15 years to work properly. The national average cost for full ductwork replacement is $1,450–$8,000; however, the cost can range anywhere from $250–$12,000 depending on home size, system accessibility, and materials used.Feb 16, 2023 · Calculate for each individual room. To calculate CFM, you need to know the size of your heating or cooling unit in tons. Multiply this number by 400, which is the average output of an HVAC unit. Then divide by the total square footage of your home. This will give you the multiplier for all your rooms’ CFM. Ducting Calculators and Air Volume Converter. Nordfab can offer technical assistance with determining whether our ducting is best for your application and with designing duct installations. Please contact us with your requirements. Input CFM Input Velocity (FPM) Ideal Round Duct Diameter Duct Friction in Straight Duct. Calculate. The duct weight can be calculated using the following formula: DW = ( (2* (H+W)) L T)*D. Where the variables are: The duct density for aluminum is 0.1 lbs/in^3. To calculate duct weight, simply multiply the sum of the height and width by 2, multiply the result by the length and thickness, and then multiply the final product by the density.TO CALCULATE DUCT SIZE: Enter Air Quantity (Flow Rate) Enter either Friction Loss or Velocity. The software will automatically detect the calculation method; Click Calculate …Air Ducts - Cross Sectional Areas; Example - Generated Noise in Duct by Air Flow. The cross section area of a 200 mm duct can be calculated as. A = π ((0.2 m) / 2) 2) = 0.0314 m 2 The noise generated in the duct with an air flow velocity 10 m/s can be calculated as. L N = 10 + 50 log (10 m/s) + 10 log (0.0314 m 2) = 45 db The noise generated in the same …Dec 3, 2023 · The Duct Pressure Loss Calculator is an essential tool used to estimate the pressure drop or loss that occurs within a duct system due to various factors such as friction, length, diameter, velocity of airflow, and gravity. Its primary function is to calculate the pressure loss (ΔP) occurring in the duct, offering insights into the system’s ... An Air duct pressure drop calculation is essential for designing and operating HVAC (Heating, Ventilation, and Air Conditioning) systems. Understanding how to calculate pressure drops in air ducts allows mechanical engineers to design more efficient and effective systems, ensuring optimal airflow and comfort in residential and commercial …HVAC Ductwork Sizing Calculator. On this page: How to size your HVAC ductwork? Understanding measurement units for ducts. Using Modernize's HVAC and …Sep 30, 2023 · Duct load calculation involves determining the heating or cooling load that a duct system must handle. It includes factors like air temperature, humidity, and the area being served. The calculation is complex and is typically done using specialized software. Formula. The formula for air duct sizing involves the calculation of air velocity (V) and duct cross-sectional area (A) to determine the air volume flow rate (Q), expressed in cubic feet per minute (CFM). Q = A × V. This equation comes from the principle of continuity in fluid mechanics which states that for incompressible flow, the product of ... V = 0.408 Q/D 2. Components. = Air velocity inside the duct (feet/s) = Air flow rate inside the duct (GPM) = Air flow rate inside the duct (inches) Metric Equation. Determine the following formula, which can be used to calculate the air duct velocity: V …The average per-square-foot cost for duct cleaning is $0.20 to $0.40. Using this standard, a 1,200-square-foot house could run from $240 to $500, while a 3,000-square-foot one could range from $600 to $1,200. When pricing this way, cleaners usually include registers and the insides of the ducts themselves, along with the air handler and …V = 0.408 Q/D 2. Components. = Air velocity inside the duct (feet/s) = Air flow rate inside the duct (GPM) = Air flow rate inside the duct (inches) Metric Equation. Determine the following formula, which can be used to calculate the air duct velocity: V …The air duct calculator, or “ductulator,” is a commonly used tool for designing and installing duct systems. Unfortunately, many designers and technicians receive limited instructions on its correct use. This lack of instruction frequently results in duct systems that fail to perform as intended. It’s typical to find that delivered airflow into ….