Attic exhaust fans are installed in the attic and are responsible for cooling the air in the attic. They let out the warm air through the vent while bringing in the cool air from outside. During the hot sunny days, the attic gets hot because of the heat energy from the sun that is absorbed. The heat may be conducted and it causes the house to be really hot. While the fan is on, it can get out the hot air and draw in the cool air making the attic, and thus the whole house, cooler. But how do attic exhaust fans work? And are they suitable for your needs? We will provide you with a guide below.
About Attic Ventilation
Attic ventilation is used to create cool living spaces and reduce temperature fluctuations in a home. When you have a completely sealed attic a lot of heat and moisture is trapped inside the attic.
The excessive heat will cause temperature fluctuation while the humidity can cause rot and growth of molds in the attic. The attic ventilation system uses a simple principle of cool air in and hot air out. It usually has two vents that are the intake vent and the exhaust vents.
Intake vents are usually located on the lower part of the roof and they allow cool air into the attic. Exhaust vents are located on the peak of the roof and they let out the hot air.
Using a process known as passive ventilation, you can vent your attic. It allows an exchange of cool and warm air.
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How Does an Attic Exhaust Fan Work?
An attic fan can get the hot air in the attic out and get in the cooler air. When the hot air accumulates in the attic, it causes the temperatures to rise in your living spaces. With an attic exhaust fan, the hot air is expelled through the vent while cool air gets in through the soft pit.
When the cold air enters the attic through the soffit, it is heated up. The heated air will rise and it will get out through the roofs vent. As the hot air is expelled, it creates a negative pressure that is filled with cool air from outside.
This creates a process known as the self-repeating ventilation process that goes on over and over. The modern units are fitted with thermostats and humidistat that make them operate between certain humidity and temperature levels.
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Does My Home Need Attic Exhaust Fans?
Attic exhaust fans are useful in some situations. Some of the conditions include:
If your home has small attic insulation, this means the attic exhaust fan will conserve much cool air for conditioning of the living space.
If your home’s attic floor is fully sealed, when the attic space lacks a vent or a soffit you will need an attic exhaust fan. A fully-sealed attic will have high temperatures because of the heat energy absorbed. The fan will be responsible for creating a cool environment in the attic which is distributed all over the living space.
If your home has a large soffit ventilation space, much air will be drawn into the attic that creates an environment that might be uncomfortable. An attic exhaust fan will push out the hot air, creating a comfortable cool environment.
If your home has HVAC equipment in the attic, here if the HVAC equipment is installed correctly, sealed, and well insulated, then you can have an attic exhaust fan.
These conditions may make you consider installing an attic exhaust fan to create a cool environment.
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Why Attic Fans Don’t Work Well and What to Do Instead!
An attic exhaust fan can sometimes work magic in providing a cool environment in the attic that lets your living spaces become comfortable. Sometime during the sunny days, hot air is drawn in from the outside that is further heated up in the attic and this might cause the temperature in your living area to rise. With powerful exhaust fans, you can have more problems than what they can solve.
If you have a ceiling with gaps and unsealed spaces, a powerful exhaust fan will expel the conditioned air making your living space uncomfortable.
Because of the backdraft effect, using a powerful exhaust fan can pull combustible gas out of your cooking appliance that is very dangerous.
An attic exhaust fan cannot deal well with moisture and condensation that can cause mold growth in the attic that is very dangerous.
With the problems associated with the exhaust attic fans, it is important to consider things like:
Ensuring you have enough soffit space and vents on the roof can be enough in dealing with the air in the attic. It is usually done during construction because doing it on a ready structure can be cumbersome.
Instead of installing an attic exhaust fan, do good sealing. A thick layer of insulating material and reflective material on top of the insulator. This will block radiation and it will separate your house from the attic leaving your living space cool.
Applying these two ideas may help you a lot to create a cool living room and avoid the problems associated with an exhaust fan.
The Downside of Attic Exhaust Fans
Mostly, attic fans do many good but there are some controversial issues associated with the attic fans.
1. Insulation Makes an Attic Fan Ineffective
Even though after insulation, the fan might conserve some heat or even increase the temperature in the attic during winter there is a problem with its insulation. The material used for insulation slows down the heat from moving around. This will make you use your air conditioning unit with a higher utility bill.
2. It Causes Loss of Conditioned Air
If you do not have a well-sealed attic, you will lose a lot of conditioned air. The attic exhaust fan will suction the conditioned air through unsealed gaps and spaces making the living space uncomfortable.
This will force you to spend more on paying for the air conditioning unit to stabilize the room’s air. With the suction of the conditioned air, it can cause major problems with combustion in your home or increase the concentration of carbon monoxide in your home.
With all the good an attic fan can do for you, there are some drawbacks to its functioning.
Attic exhaust fans can help a lot in reducing temperature fluctuation in a home. But they can cause many problems in a home. Therefore, it is important to choose the best-quality attic exhaust fans to make ensure that you don’t waste your money. Below we cherry-pick the top 3 attic exhaust fans that you can buy without worries.
Top 3 Best-Reviewed Attic Exhaust Fans