To determine the number of cubic feet per minute needed for a power vent fan multiply the number of square feet in your attic by 0 7.
Do i need a solar attic fan.
As the sun gets lower in the sky when attic temperatures are at their greatest the fans slow down.
The amount of solar attic fans a home needs will ultimately depend on many factors.
If a cloud blocks the sunlight the fans slow or stop.
You need the fans to be operating at.
The point of having an attic fan is to lessen the load on your ac system saving you money.
To reduce that expense some homeowners buy an electric or solar attic ventilator.
You need that amount of air if not more to get any sort of cooling benefit from the fans.
If your attic space is over 1 800 square feet you will need enough solar fans to move 8 000 cfm.
That means you will need to double up your investment in this area.
Ft of attic space for example 20 x 50 to be effective.
You will probably need two solar attic fans to get the results you want.
Electric attic fans however often increase energy consumption and cancel out any savings unless the attic is not insulated at all.
But they re much easier to install since no wiring is needed.
Solar powered attic vent fans usually don t move as many cubic feet of air per minute cfm as hardwired fans.
This fan moves 1 000 or more cubic feet of air per minute creating low pressure in your attic.
Attic fans can create a negative pressure condition in your home causing vented appliances to backdraft.
Powered exhaust vents feature an electric or solar powered fan to create an effect similar to that of a turbine view example on amazon.
All you need to know about attic ventilation.
This backdraft can bring dangerous and toxic fumes into your home like carbon monoxide an odorless and deadly gas.
Many are solar powered and require no other wiring so they don t cause any additional charges on your electricity bill at all.
According to the home ventilating institute hvi powered attic ventilators need to move a minimum of 700 cubic feet per minute cfm for 1 000 sq.
Intense sunlight can create heat faster than one or two small fans can cool an area.
In addition to soffit gable and or ridge vents you may want to add a power vent fan to your attic to increase air circulation.
Because solar attic fans operate with a lower power output they are unable to move as much air as some of the other options that are available.
Because what happens is attic fans are so strong that they actually reach down into the conditioned space of your house and they do that by using the wall cavities and where the outlets and pipes come through the walls as places where they draw air from the inside of your house it s that air conditioned air and it ll pull it right up into the attic and exhaust it outside.
Vaulted ceilings obstructions and the amount of existing ventilation from soffit vents ridge vents and gable vents should all be considered.
