Q. What is an attic fan?
A. An attic fan or power attic ventilator is a specially designed fan for exhausting hot air from attic space. The fan is mounted up on the roof, near the top, drawing the hottest air out first while drawing in cool air from strategically located inlet vents. The Jet Fan Attic Fan will get rid of the worst of the heat from the sun beating on your roof the easy way by simply blowing it out. You will be able to get your home cooler on really hot days, the air-conditioner will run less, saving power and wear and tear on the air-conditioner, and your home will cool off sooner at night.
Q. Will an attic fan look funny on the roof?
A. No, the fan housing is only 8″ high and 22″ in diameter. It can only be seen from one side of the house, normally the backside.
Q. How much power does an attic fan use?
A. Very little, 250 watts. Much less power than an air conditioner uses to cool the effect of your hot attic air.
Q. How do you operate an attic fan?
A. An attic fan is automatic. An adjustable thermostat, which is included, turns the fan on and off according to the temperature. If you have a humidistat installed, it turns the fan on and off as well according to the humidity. You could have your electrician put in switches as a master off switch or a by-pass switch so you can turn it on whenever you want.
Q. Will the attic fan suck out my air-conditioned air?
A. No. Air is taken in from the outside through the attic vents in the eaves, gable wall louver vent or other roof vents. Care should be taken to follow the instructions when installing and attic fan so that there is enough intake area provided for the fan to move its rated capacity of air and to minimize negative pressure in the attic. Air within the house should not be drawn into the attic as long as your ceiling is intact and the scuttle access closed. House air can be sealed off from the attic better by using expanding foam around pipe penetrations in the top-plate of your walls and around light fixtures and duct-work that may pass through your attic.
Q. When does the attic fan operate?
A. Set the adjustable thermostat to turn the attic fan on at 100ºF, and off at 90ºF. If you have a humidistat, set it to turn on at 70% humidity.
Q. What is a humidistat and why would I need one?
A. We do not recommend a humidistat unless your home experiences below freezing winters. If your bathroom fans or kitchen fan are blowing into the attic then that should be corrected first. Attics can have higher humidity because of cold outside air temperatures during winter. Because water vapor from cooking, showers and the homes own humidifier is lighter than air, it is constantly trying to leak up into the attic through small gaps in the ceiling, around light fixtures and other ceiling penetrations. This attic vapor can condense and cause a dampness, frost and mold to grow. Set the optional humidistat to 70% so it turns the attic fan on regardless of the temperature. Care must be used to assure that there is enough air coming in from the outside through vents that you have or that you may add. The instructions provided show the minimum square inches of venting required to make sure the fan is using outside air and not sucking warm humid air out of your house and possibly making the attic humidity worse.
Q. What is a firestat and why do I need one?
A. A firestat senses when the attic is at 180 degrees; which indicates a fire and shuts the attic fan off so it does not make the fire worse. Most attic fans on the market do not have this feature. For safety’s sake, make sure your attic fan has this feature.
Q. Where is the best place to locate an attic fan in the attic?
A. It should be located within a few feet of the peak of the roof as far away from other roof vents as possible so there will be more cross-flow. If your home has eaves, adding eave vents is usually the best alternative because it draws air from the shade and provides more cross-flow to the fan.
Q. What color do the attic fans come in?
A. Jet Fan Attic Fans come in the natural aluminum color.
Q. Will the roof leak after installation?
A. No, the fan has a one-piece heavy metal flashing. The flashing fits under the shingles above and lays over the shingles below. Water runs right off. In sever wind a little rain or snow my blow in but will not cause any damage.
Q. How big is the attic fan?
A. The smaller fans have a 14″ blade diameter. The jf707 moves 800 CFM @ 0.03 SP and covers 1000 square feet of attic floor; the jf727 moves1200 CFM@0.03SP and covers 2300 square feet of attic floor, the larger jf747 has a 16″ blade and moves air 1650 CFM@0.03SP and covers 3200 square feet of attic floor.
Q. The attic frame rafters are only 14-1/2″ apart, will the Jet Fan fit?
A. A Jet Fan attic fan is installed on top of the roof decking and does not go down into the attic. The rafter spacing doesn’t matter. One limitation is that the center of the opening cut has to be 4 or more inches from the nearest rafter to leave room for the motor which does come down 1 inch below the top of the rafters.
Q. How much money can I expect to save?
A. Exact savings depend on the style of the house. Generally, the more ceiling area directly below attic space that a house has, the more you stand to save. Savings after the cost of the fan will be realized in any house with air-conditioning within two or three seasons along with added comfort.
Q. What is a whole house fan?
A. Sometimes whole house fans are called attic fans. However, the whole house fan is an entirely different concept. Whole house fans draw air in through the windows of the house and blow hot house air out through the attic. Of course a whole house fan would never be used simultaneously with an air conditioner or when is it is too hot or humid or dusty and especially if you have allergies during those times of the year.
Q. I have a whole house fan, do I need an attic fan?
A. The roof-top Jet Fan Attic Fan will help your whole hose fan work better by providing another way for air to pass to the outside even though the roof-top Jet Fan Attic Fan will not be running. If you have and air-conditioner, you will probably want to use it when it is too hot and humid. The Jet Fan Attic Fan will get rid of the worst of the heat from the sun beating on your roof the easy way by simply blowing it out. You will be able to get your home cooler on really hot days, the air-conditioner will run less, saving power and wear and tear on the air-conditioner, and your home will cool off sooner at night.