Ask the Knowledgeable: Is an attic fan an excellent funding for my house?
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Is an attic fan a good investment for my home?
There is a lot of confusion around attic fans. Studies have shown that if your attic is properly ventilated with a ridge vent and your attic is well insulated, you don’t need an attic fan. A ridge vent is an opening along the ridge that allows air to enter the lower eves of your attic to naturally vent hotter air from the attic through the ridge vent with natural convection.
Before giving a simple yes or no answer to this question, you need to understand that there are several types of attic fans in the market.
Whole house fans are intended for use in non-air-conditioned houses. Whole house fans are used to bring fresh air into your home, through open windows and through your attic. If you live in the right climate, whole house fans are a great way to keep your house cool day and night, using only about 10% to 15% of the power drawn by a central air conditioner. In the US, this type of fan makes more sense in the dry west than in the wetter eastern part of the country.
If you use this type of fan in our region, humid and unfiltered outside air may be introduced into your house. Many people not only use their central air conditioning system to cool their homes, but also to dehumidify and filter the outside air, reducing dust and allergens through a centralized filtration system. A whole house fan is the opposite of your central air system, even if it’s only used at night.
In most cases, a whole house fan is mounted in the attic above a rectangular grille in the ceiling of a central hallway. The fan draws warm air from inside your home and blows it into the attic. Since whole house fans are relatively powerful, they quickly vent the hot indoor air and let in cooler outside air through open windows. As soon as the house has cooled down, the fan can be switched off and the windows closed. Typically, whole house fans are used at night to bring in the cooler air and then the windows are closed from early morning to evening to prevent the cool air in the house from escaping.
Even if full house fans make sense in your home, they might not be a good choice for the following reasons. If your home is in a neighborhood where open windows can be a security concern; Whole house fans create a large hole in your ceiling that is likely to cause a great deal of heat loss in the winter, increasing your heating bills. whole house fans are loud; and finally, if you are using full house fans, atmospherically ventilated equipment in your home such as a gas fired water heater can cause a retreat. possibly creating a carbon monoxide problem.
A powered attic fan (Attic Fan) has a different purpose: to lower the temperature of an attic by sucking hot air from the attic and replacing attic air with outside air through roof vents. The idea is to save energy by reducing the running time of your air conditioner by keeping the loft cooler. The consideration is that a powered attic fan will reduce some of the heat load on the top floor of your home, thereby saving energy by making less use of your air conditioning.
Powered attic fan are usually mounted on a sloping roof or the gable wall of an attic. Most powered attic fans are thermostatically controlled so they turn on when the attic gets hot. While the logic behind powered attic fans is compelling for many homeowners with hot climates, these devices can cause some problems. A powered roof fan needs fresh air to work effectively. If your roof soffits aren’t enough, the roof fan will find other ways to get the air it needs, which can be a problem.
In many households, electric attic fans draw conditioned air from the house into the attic through cracks in the ceiling. The net result: powered attic fans increase cooling costs instead of lowering them. While the cool air is being sucked out of the house through the ceiling, hot outside air enters the house through other cracks to replace the exhaust air. The net result: the air conditioner has to work harder than ever because it struggles to cool all of the outside air entering.
Several studies show that using an electric attic fan doesn’t always save more electricity than it uses. even in a newer house with no cracks or air leaks.
A more alarming problem is that powered attic fans can also depressurise a home to the point where gas appliances such as water heaters and boilers used to heat domestic water are leaching dangerous gases into your home. The potential for hazardous conditions in households with exhaust fans is increased in summer if gas appliances are switched on at the same time as the fan. The negative pressure created by the roof fan causes carbon monoxide to be fed back into your home instead of exhausting it through your chimney. This can create a potentially dangerous condition for your family.
If your attic is too hot, this isn’t necessarily a problem. If there aren’t any plumbing or HVAC up there, who cares how hot it gets? Finally, you should have a thick layer of insulation in your attic to insulate your hot attic from your cool house. If you have plumbing or HVAC equipment in your attic, seal up any leaking plumbing and make sure your plumbing is wrapped in insulation.
If you think your house will have a hot ceiling in the summer, the solution is not an electric attic fan. The solution is to seal any air leaks in your ceiling and add more insulation to your attic.
Donald Pagano, President – DRP Electrical Contracting
(718) 447-7275 [email protected]
All of our experts are licensed, bonded, and insured members of the Staten Island Chapter of The Home Improvement Contractors of Staten Island. Homeowners should always consult with licensed professionals, review a contractor’s license through the NYC Department of Consumer Affairs (call 311 for information), and ensure their project complies with NYC DOB regulations before embarking on a home improvement project.
To ask questions about your home improvement, contact: [email protected]