WHOLE HOUSE FAN SIZING FORMULA 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.
However, a constant flow of air is required to remove the heat that is radiating from your rooms, walls, ceiling and attic. i.e. A 2000 sq. ft home, would need a 3000 CFM rated fan to achieve the 1.5 CFM Per Sq. Ft.
80 to 100 cfm continuous will be more than enough for this house. 200 cfm peak for source point and winter humidity control if needed will be plenty.
For most homes, a rule-of-thumb is to just multiply the total square footage of the attic by 0.7 to find the minimum ventilation rate in cubic feet per minute (CFM). For homes that have dark shingles and/or steep roofs, the multiplier is increased by 15%, to 0.805.
If the peak attic height is only 2 feet, you would need at least 750 CFM. If the peak attic height is 6 feet, you would need at least 2250 CFM, and so on. This math formula will work every time, for any size attic, and as always the more airflow the better.
A whole-house fan's airflow capacity, in cubic feet per minute (CFM), is an important consideration. Your home's size and layout determine the appropriate CFM. Choose a fan that can circulate your home's air 15 to 20 times each hour, as a good rule of thumb.
On the other hand, if your CFM is too high for your room size, it can cause ventilation problems. Too much air results in too little ventilation, which in turn causes high humidity. The excess moisture in the air can then lead to mold and mildew, as well as other problems.
To estimate the size of your attic vents you'll need at least one square foot of space for each 750 CFM. Therefore, if you choose a 4,000 CFM system, you should divide 4,000 by 750, which means you need at least 5.3 square feet of attic venting. If you go with a 6000 CFM system you will need 8 sq ft of attic venting.
4. Structural Issues: The high airflow from an oversized fan might cause undue stress on your home's structure, including ductwork, attic vents, and other components. This can lead to damage or the need for additional structural support. 5.
The first things to consider when determining your ideal range hood CFM are your cooktop's width and BTU capacity. The general guidelines for each of these features are as follows: 100 CFM for every 12 inches of stove width. 100 CFM for every 10,000 BTUs of heat capacity.
Whole house fans should be designed to provide an air flow that is at least one half the total volume of the house (for example, an 8,000 ft3 house would need at least 4,000 CFM of airflow ). Consult with a qualified professional to determine the appropriate airflow for your home.
Choose a fan that can ventilate at least 1 CFM per square foot of room. So, for an 80 square foot bathroom, select an 80 CFM fan. For bathrooms 50 square feet and smaller, it's recommended you purchase a bath fan designed for small rooms. In other words, choose under 79 CFM bath fans.
When running a whole house fan if you don't open windows it makes a loud suction noise to make it very obvious that there aren't windows opened. Make sure to follow these important tips safety tips when using a whole house fan: Make sure you have the 2-4 windows open 4-8 inches.
WHOLE HOUSE FAN SIZING FORMULA
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.
For most, the requirement is 300 to 1, meaning one square foot of ventilation is required for every 300 square feet of attic floor. That one square foot is then divided equally between intake and exhaust. Even with all the same type of vent, you need to have them in proportion to your intake vents.
The higher the CFM, the more air the fan circulates, making it more effective at cooling your room. For a standard room with an 8-foot ceiling, a fan with a CFM rating of 4000 to 5000 is generally sufficient. However, for larger rooms or rooms with higher ceilings, you might need a fan with a higher CFM rating.
Electric and induction cooktops release less heat and as a result, they require a less powerful range hood. Often, a ventilation power varying between 350 CFM and 500 CFM is sufficient, depending on your cooking habits.
You can calculate the CFM needed for your system. Start with the total volume of air (in cubic feet). Divide by the exchange rate (how quickly you want to replace the air), and the result is the total CFM you need for your system.
Do not run your whole house fan during the day unless the temperature outside is cooler than the house is inside, though you may want to run the fan during the day to push air out of the attic. To do so, direct airflow from either the basement or the shady side of the home.
Use high speed to 'kick-start' the cooling, and use low to run quietly through the night. Make sure at least one window is open. Opening two or more windows halfway or wider is recommended to allow the fan to do its job. For general cooling, open windows far away from the fan to provide airflow to the whole house.
QuietCool Stealth 4.8 vs Trident 4.8 vs Classic 4700 vs Energy Saver 4700. The Stealth 4.8 is arguably the best whole house fan QuietCool makes.