|
|
|
Summary: Attic fans are different from whole house fans. Often people confuse them to be house fans. Solar attic fans use solar energy to remove hot air in the attic. This is a new product range. Whole house fans are on the other hand move hot air from the living spaces as well as the attic simultaneously.
Question: Can you tell me how a whole-house fan differs from an attic fan? Which of them is better for my home? How can the best cooling effect be achieved with these fans? What are the kinds of problems encountered by both these types of fans.
Answer: The attic fans and whole-house fans are fans which move air. But then they are like apples and oranges, though fruits no doubt are not similar in any other ways.
A whole-house fan is usually located as a fixture in the ceiling of a house. Of course, they may rarely be found to be sited in a wall. Most often this is sited at some place central in the home or in a hallway. To direct the blow of the air into an attic space, the fan is located always on the wall or on the highest ceiling and oriented suitably.
Large volumes of air are moved by a standard whole-house fan. To make sure that thousands of cubic feet of air is moved every minute, the fan should be large with considerable pitch. It will take barely five minutes to remove hot stale air from inside a ranch home that is average in size of 2,400 square feet finished floor space. Simultaneously the air from outside, which is cooler, replaces the hot air.
The whole-house fans are intended to move air through the house. This air is then exhausted into an attic space. The fans are very effective cooling devices particularly in the area where you live with its low humidity. The cooling is most effective in the early morning or evening hours when the inside of the house is quite warm while the outside temperature is quite low. The cooling effect drops when the humidity outside rises during the day.
The attic fan as compared to whole-house fans works entirely differently.
The major departure is that the attic fans are designed as fans that are smaller moving only hundreds of cubic feet of air every minute from out of the attic space only. They do not have the capacity to move the air through your home. The principle on which the cooling is effected is rather straight forward. When the warmer air in an attic, say 140-160 F, is replaced with air which is 85-95F, your home too begins to become cooler. The air-conditioning systems could get highly stressed with the heat gain due to hot attics and very hot ceilings. The capacity of the air-conditioner to cool is then pushed to its limit.
Whether whole-house fans or attic fans, their capacity to cool depends on how easily and fast they exhaust the air outdoors. Usually the attic fans does this function better. That is because they are invariably located on the side of a wall or in the roof with an opening cut out to install the fan. Intake vents placed along the length of the lower ends of your home are required for the attic fans. Venting has to be continuous for maximum effect. The air from outside has to enter the lower region of the attic at the place where roof goes above the outside walls of the house without any hurdles. The whole of the attic space is cross ventilated very well as most attic fans usually are positioned on top of a roof.
If the intake air vents are not enough for the attic fans, then air from inside your house is drawn in. This suction is caused by the partial vacuum caused by the spinning of the blades of the fans. The air conditioner you use in your home means money spent. The idea of sending cool air up into the attic from inside the home is indeed a bad idea.
Ample exhaust air vents all the way through the side walls of the attics or through the roofs are required by the whole-house fans to function efficiently. In order that these work properly, the manufacturer of whole-house fans will inform you the exhaust ventilation net-free area that is required for each of the sizes of fans. If this exhaust ventilation are is not provide, you will find that though the fan blades spin, the movement of air would be limited.
Hot air is also removed from the attic when whole-house fans are turned on. But when the attic heats up by mid-day, you will not wish for the whole-house fan running circulating the hot air. It makes a lot of sense that a house has both categories of fans which serve two different purposes. The whole-house fans operating in the morning and evening, and the attic fans running during the day makes the home cool.
Whole-house fans with timers are also available. If you sleep turning on the whole-house fan on during the night, it could get so chill that you will need blankets. Within a few hours, the temperature of the house is lowered to a comfortable level.
With the windows of a few select rooms open, the whole-house fan really cools your home. The open windows bring in a comfortable breeze into your room when the fan is on. Before the whole-house fan is turned on, make sure that the windows are open. Otherwise if there is a fireplace, air is sucked in down through the chimney stirring up the ashes if there is any. This will generate a nasty ash storm. The whole-house fans such the ashes and then spread around throughout the house. You might well ask how I know about this. This is a lesson taken from experience.
© Copyright www.diystuff.com
Top of Page
|
|
|
|
