Should attic fans be used with gable vents? Certain attics may even require an attic fan due to lack of venting options. When proper ventilation isn't set up on some brick and stucco homes, adding a fan will help. Or if the home style will be taken away from by adding gable vents. Some HOA rules are against changing of any original designs that will visually reduce property values. This is not taking into consideration what improper ventilation will do to a home or how quickly this will reduce a property's value bringing down an entire neighborhood. In cases such as dealing with an HOA, proper planning upon your part can be the deciding factor. Bringing to the neighborhoods attention of the builder not properly venting most homes attics will give the upper hand in most cases for additional gable vents or venting options to be approved. As long as they are aesthetically pleasing. The HOA is only there to maintain the neighborhood's property values. They usually know nothing of structure or beyond the color paint allowed. But if you plan on being in your home over 10 years, this should be a high priority as preventative maintenance. Looks great now, but soon the roof is cooking inside and out, boards are swelling or rotting, plywood decking is being pushed and pulled until it buckles. This average $500 fix may cost $50,000 in just 10 or 15 years when the entire roof needs replaced.
In the case of an attic fan being used because of insufficient or missing soffit / cornice vents to draw in cool air, use only one fan. The gable vents should be on the East and West of the home to vent only with gable vents. If the morning sun favors one gable vent, that will act as your intake vent in the evening. Leaving the evening sun gable vent to exhaust the heat. Morning are almost never hotter than evenings is why we concentrate on the evening sun side of the home. The fan should be placed about 2 feet behind the evening sun gable vent and set to turn on about 130 degrees. Around lunch when the sun is over the roof, the attic should be reaching this temperature and triggering the fan to turn on. The cooler air is already building at the opposing vent and ready to be drafted in. By pushing the hot air out, the cool air will be sucked in to cool the attic.
The other option is to place the attic fan at the morning sun gable vent but blowing away from the vent into the attic. Again place the fan about 2 feet away from the gable vent. Continuous forceful winds can cause excessive wind vibrations on the louvers or slats and shorten the life of the vent. By using the fan to draw in cool air from the cooler side, the air will be allowed t act more natural and create a vortex. This sideways tornado air movement will circulate fresh air throughout the attic and keep it from becoming stale. It is more ideal for a healthier attic and roof. By using the cooler vent, the fan should be set closer to 100 degrees or it will not turn on when the other end of the attic is hot and ready to vent.
So, why not use an attic fan on both vents or exhausting each vent instead of as an intake? Multiple fans incorrectly set up or being used too closely together can an usually will work against each other. Fans fighting each other without the proper cool air intake will overheat and catch fire. This is why we suggest placing the fan in the coolest evening vent as the intake vent and allow the hotter vent just naturally do it's job. This will ensure the fan the coolest spot to not overheat and more fresh cool air to circulate refreshing the attic. If all vents are exhaust vents due to fans, there will be no cool air to circulate. They will only draw hot and shut off if cool air is detected. One main consideration is that these attic fans are thermostat controlled electronics in a hot attic. Electronics do not always fair well in heat. These will need to be occasionally monitored for chewed or frayed wires as well as spider webs and dust build up. Before the first hot day of summer when the fan should start up, take a gander for a moment and possibly prevent an attic fire. Replacing a roof due to overheating and dry rotting at 10 to 15 years is expensive but an attic fire might cost even more.