1) Determine the total cubic feet of air in the living area in the residence. (Multiply square footage by ceiling height). 2) Divide the fans CFM (cubic foot of air movement per minute) into the total cubic feet of the home to determine the amount of time to perform one air exchange.

How many CFM do I need for 1000 square feet?

If you only need the air changed 1 time per hour (ACH = 1), then just . 135 CFM is needed per square foot of space. So, a 100 square foot room would need 13.5 CFM. A 1,000 square foot room would need 135 CFM.

How many CFM do I need for a 3000 sq ft house?

CFM Chart For Common Room Sizes

Room Size: CFM (At 2 ACH)
How many CFM for a 1500 sq ft home? 400 CFM
How many CFM for a 2000 sq ft house? 533 CFM
How many CFM for a 2500 sq ft house? 667 CFM
How many CFM for a 3000 sq ft house? 800 CFM

What CFM whole house fan do I need?

We use a general formula of either 2, 2.5, or 3 CFM, or “Cubic Feet per Minute”, per square foot of living space. 2 CFM would provide a good system, 2.5 CFM would provide a better system, and 3 CFM would provide the best system.

How do I determine what size attic fan I need?

Most manufacturers recommend sizing an attic fan at 2 to 3 CFM (cubic feet of air per minute) per square foot of living space.

How many CFM do I need for 1200 square feet?

One cfm is needed per square foot (1 cfm/sq ft) of floor area. This is the average air quantity required for a room or an entire building. This number is based upon an averaged heat load calculation for comfort cooling.

How many CFM do I need for a 2000 square foot house?

Heat and energy recovery ventilators

Total area of home (square feet) Continuous ventilation rate
1,000 square feet 50 CFM
2,000 square feet 100 CFM
3,000 square feet 150 CFM

How do I calculate CFM for my house?

This practical math formula goes a long way when you’re considering air ventilation improvement in an indoor space:

  1. CFM = (fpm * area), where fpm is the feet per minute.
  2. To find the cubic feet per minute, substitute the FPM value with the area after the area is squared.

Is a higher CFM better?

A: Airflow quantifies the amount of air a ceiling fan delivers and is measured in CFM which stands for cubic feet per minute. CFM measurements are taken when a fan is on high speed, then that number is divided by the watts used. This means that the higher the CFM, the more efficient the fan, and the more air it moves.

How many CFM does a 80000 BTU furnace?


80,000 BTU 96% AFUE Variable Speed Goodman Gas Furnace 1600 CFM – Upflow/Horizontal
Furnace Efficiency / AFUE 96%
Heating BTU 80,000
Blower Motor Variable Speed – ECM
Maximum CFM 1600

How many vents do I need for a whole house fan?

Venting Requirements
A rule of thumb is that you should have one square foot of “net free venting area” for every 750 CFM of airflow. So at 3000 CFM, you’ll want four square feet of venting. Most modern homes easily accommodate this rule, but it is important to check to ensure optimum system efficiency.

How much airflow do I need in my attic?

Most codes use the 1/300 rule for minimum residential attic ventilation recommendations. This means that for every 300 square feet of enclosed attic space, 1 square foot of ventilation is required – with half at the upper portion (exhaust vents) and half in the lower portion (intake vents).

How many cubic feet is my attic?

Attic volume is calculated the same way – LxWxH. When the roof pitch is the same on both sides of the roof you can multiply the length of the roof section times half the total (building) width times the height of the roof.

How many CFM is a 2 ton unit?

1 ton of cooling is equal to 400 cubic feet of air per minute. 2 ton of cooling is 800 cfm and so on.

How many CFM do I need per square foot?

Divide the home’s square feet by required system airflow to find average cfm per square foot. Here’s an example: Required system airflow is 1200 cfm. The square feet of the home is 2000. Divide 1200 cfm by 2000 square feet.

How many CFM is a 1.5 ton unit?

How Many CFM For 1 – 6 Ton Units? ( Chart)

Unit Tonnage: CFMs Required:
1.5 Ton Unit 600 CFM
2 Ton Unit 800 CFM
2.5 Ton Unit 1,000 CFM
3 Ton Unit 1,200 CFM

How many CFM do I need?

The rule of thumb is that you need at least 1 CFM per square foot of room area. To determine the square footage of your bathroom, multiply the length times the width. For example, if your bathroom is six feet wide and nine feet long, its square footage is 54. Therefore, it should have a fan rated for at least 54 ​CFM.

How many CFM is a 2.5 ton unit?

For instance a 2.5 ton system (Approximately 400 CFM per ton) would require (2) 14” flexible return ducts or (1) very short flexible 18” duct to move the 1000 CFM required by the 2.5 ton system.

How many cubic feet will a 3 ton AC cool?

3-ton is equal to 36,000 BTU. If you apply the 20 BTU per sq ft rule of thumb, you can see that a 3-ton air conditioner cools about 1,800 square feet spaces.

What size AC unit do I need for a 1800 sq ft house?

1,201 to 1,500 square feet homes should use 2.5 tons. If your home size is higher than the number above but is less not more than 1,800 square feet, you can go for a three-ton A/C. Choose a unit that is 3.5 tons if your home measures more than 1,800 but not more than 2,100 square feet.

What happens if my AC unit is undersized?

As previously mentioned, air conditioners absorb heat and humidity from your home. If your unit is too small for the square footage, it won’t absorb all of it. This means you’ll be sitting in a room that feels just as hot as outside, completely undoing all of the good work of paying to run an AC unit.