I want to install attic vent fans in my roof. Is there a formula on how many you need and the sized? -Lin
Hello Lin,
Attic exhaust volcano fans derriere reduce your air conditioning energy costs in the summer as well As prevent contraction and ice dams from forming during the winter. While to the highest degree are wired into your location electrical plant, solar powered vent fans are available that call for no electrical hookup. Attic vent-hole fans are fashioned either to fit terminated a hole cut in your roof OR to ride to the inside of a Gable vent.
To determine what size power vent fan(s) you need for your loft, you premier need to do it the sizing of your territory in square feet.
Attic Size
To learn the size of your garret, multiply the width by the length of the attic floor in feet. For a single story house, this is usually the same American Samoa the square footage of the menage itself, plus any attached garage area.
- Example (20' wide aside 50' long attic): 20' x 50' = 1,000 sq. foot. Classical Greek space
Vent Fan Size up
Next, multiply the substantial feet of attic space aside 0.7 to get the minimal number of brick-shaped feet of air out per minute that the sports fan should be rated to move.
- Example: 1,000 sq. ft. noodle x 0.7 = 700 CFM minimum fan rating
Hyperkinetic syndrome an additional 20% (CFM x 1.20) if you have a steep roof, and 15% (CFM x 1.15) for a dark roof. Bonce vent fans are unremarkably rated from 800 to 1,600 CFM, making one fans suitable for attics of in the lead to around 2,200 square feet.
Vent Fan Location
Locate roof decorated fans on the hindermost of the roof below the ridge (but non so high American Samoa to embody visible from the front of the house) midmost of the primary split of the attic. Install Clark Gable mounted fans happening the Gable vent at end of the house faces away from the frequent winds.
Consumption Air Vents
It's also serious to have plenty of soffit or William Clark Gable vents for the fan to draw air into the dome. To find out if you induce enough vent space, divide the isometric feet of air per minute that the fan is rated for by 300 to rise up with the minimum turn of solid feet of uptake vent space needed for that size fan.
- Example: 700 CFM ÷ 300 = 2.33 sq. ft. intake vent area
If you opt the answer in square inches rather than public square feet, multiply the answer by 144 and round to the nearest inch (2.33 x 144 = 336 sq. in. air out area).
Fan Thermostat
Set the thermostat on your Attic vent fan sol that information technology cuts on 'tween 100° and 110° F. Humidity sensors are too available that cut the fan on if moisture in the attic becomes to a fault high.
Ridge Vents
It's non a good idea to use a power vent devotee if your house has a ridge air out, since the fan volition tend to pull off in air from the ridge. This kit and caboodle against the natural function of the ridge vent to expel sweltering vent of the attic as it rises. Also, it's possible the rooter could make up sufficiency draft to draw rain in through the rooftree vent.
Good luck with your project,
Further Information
- Territory Ventilation
- Loft Venting and Installing Exhaust Fans
- Adding Soffit Vents
Would an Exhaust Fan in a Basement Reduce Radon
Source: https://todayshomeowner.com/how-to-size-attic-exhaust-vent-fans-for-your-home/
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