Table of Contents

CFM Sizing Chart For Metal Round Ducts (50-2,000 CFM) Duct Size (Inches) Metal Duct Airflow (CFM) 5 inches 50 CFM 6 inches 85 CFM 7 inches 125 CFM 8 inches 180 CFM.

## How far can you run 6 round duct?

When you go from 6″ round to 6″ oval, you get 110′ of equivalent length. Wow! That means that a fitting that is somewhere around 1′ in actual length reduces the air flow as much as 110′ of straight 6″ duct.

## How many CFM is a 5 inch duct?

The 5” pipe carries 615 CFM at 4500 FPM (see chart above).

## What size duct is needed for 1200 CFM?

At 600 CFM, the minimum duct size is 6”. At 900 CFM, the minimum duct size is 8”. Finally, at 1200 CFM and above, consider a 10” diameter duct or larger.

## What size duct is needed for 2000 CFM?

Rectangular equivalent diameter for air flows between 100 – 50000 cfm. Air flow – q – (Cubic Feet per Minute, cfm) (m 3 /s) Rectangular Duct Sizes (inches) (mm) x (mm) 1700 (0.77) 10 x 22 14 x 15 1900 (0.86) 12 x 19 14 x 16 2000 (0.9) 10 x 25 12 x 20 15 x 16 2500 (1.13) 14 x 20 15 x 18.

## How many CFM is a 60000 BTU furnace?

400cfm/ton, a 60,000 btu furnace probably has a 3 ton drive. 1200 cfm.

## What is the good rule of thumb in sizing Ductworks?

Determining the Right Duct Size When you hire a professional to install your ductwork, they’ll often size your HVAC ducts using a rule of thumb that states an air conditioner with one-ton capacity should be installed for every 500 square feet of air-conditioned floor area.

## What size ductwork do I need for a 5 ton unit?

Using this approach, two 20-in. x 25-in. return grilles will be the right choice for a five-ton HVAC system in order to actually deliver 2,000 cfm back to the blower without causing the return to hemorrhage.

## What size ductwork do I need for a 3 ton unit?

Multiply the tonnage, 3.5, by the total BTU per ton and this will give you the total BTU rating. Multiply 6 x 42 to determine the duct size of 252 square inches The clear are of the duct must be at least 252 square inches This measurement also includes the opening in the floor at the bottom of the return.

## How do you calculate CFM for duct size?

Duct CFM Calculation Formula Room CFM = (Room load/Whole house load) ✕ Equipment CFM. 24,000 BTUs ÷ 12,000 BTUs in 1 ton = 2 tons ✕ 400 CFM per ton = 800 CFM. Room A = (2,000 BTUs ÷ 24,000 BTUs) ✕ 800 CFM. Room A = 66.67 CFM.

## How many CFM is a 12 inch duct?

The rule of thumb for a 12 inch duct is 715 cfm.

## What size should my return air duct be?

A typical supply vent is 4 by 10 to 12 inches and a typical return vent is 16 by 20 inches or larger. Houses often have two or more return collecting points, each with a filter, which join before re-entering the heating unit. Two-story houses will have one return downstairs and another upstairs.

## What happens if ductwork is oversized?

The Ducts Are Too Large Not much. This is what happens when your air ducts are too big for your system. Your system pushes air into the ducts, but the ducts are too large for it to build up any sustained amount of air pressure, and thus a “forced air” system doesn’t have any force.

## What size duct do I need for a 12×12 room?

A 12×12 foot room will need a 4×8 inch supply duct to get an adequate CFM rate, which is about 144 CFM.

## Is round ductwork better than rectangular?

Round air ducts are best suited for high-pressure HVAC systems. Their design creates less friction, allowing air to flow easier throughout the building. Rectangular ducts aren’t as efficient with their airflow, which means they can create more harm than good in a high-pressure system.

## How many CFM does a 80000 BTU furnace?

80,000 BTU Furnace, 80% Efficiency, Single-Stage Burner, 1600 CFM Multi-Speed Blower, Upflow/Horizontal Flow Application.

## How many cfm is a 90000 BTU furnace?

90,000 BTU Furnace, 80% Efficiency, Single-Stage Burner, 1,600 CFM High-Efficiency Blower, Upflow/Horizontal Flow Application.

## What size furnace do I need for a 3000 sq ft home?

Chart For Furnace Tonnages And BTUs For 500 – 3,000 Sq Ft Houses House Size (Sq Ft): Furnace Size (in BTUs): Furnace Size (in Tons): 2800 sq ft home 126,000 BTU furnace 10.5 tons furnace 2900 sq ft home 130,500 BTU furnace 10.9 tons furnace 3000 sq ft home 135,000 BTU furnace 11.3 tons furnace.

## How many cfm do I need for 600 square feet?

160 CFM Room Size: CFM (At 2 ACH) How many CFM for a 500 sq ft room? 133 CFM How many CFM for a 600 sq ft room? 160 CFM.

## What are standard duct sizes?

Rectangular HVAC Duct Sizing Rectangular or square ducting comes in standard sizes ranging from 3 inches by 7 inches to 35 inches by 40 inches. Sizing is based on airflow needs per cubic foot per minute, as well as velocity.

## What is the standard friction loss that supply ductwork should be sized by?

Typical values used for friction loss are 0.1 in H2O/100 ft (0.85 Pa/m) for supply ducts and 0.08 in H2O/100 ft (0.65 Pa/m) for return ducts.

## How do you size a flex duct?

Measure the length and width of the room where the flex duct will be supplying the air. Multiply the length and width together to get the square footage of the room. For example, a 10-by-10 room will be 100 square feet.