In our central California climate, an attic fan is equally important in summer and winter — but for different reasons. In summer, heat accumulation in a poorly ventilated attic can send temperatures up to 150 degrees. All that heat baking the wooden structure of the attic and sub-roof can be damaging. Even worse, it migrates down into living spaces and makes your A/C work harder, raising utility costs. During winter, humid air infiltrating from rooms below condenses in the cold attic. This saturates attic insulation, destroying its heat-resistant properties. The wet environment also promotes mold and warps wooden structural components.
The year-round remedy for these ills is an attic fan to exhaust superheated air in summer and humid air in winter. Standard passive ventilation that circulates air through soffit vents and out through the vents on the roof is often insufficient to keep pace with the accumulation of hot or moist air in the attic. Here’s how a powered fan boosts the passive effect:
- Mounted on the roof peak, a fan increases the circulation of attic air, creating additional negative pressure inside the attic. This draws more air volume in through the soffit vents and exhausts it out through the roof vents, reducing heat and humidity.
- A properly sized fan will turnover the entire air volume in the attic 10 times per hours. A fan that moves 850 cubic feet of air per minute will ventilate an attic up to 1,200 square feet. To adequately ventilate up to 3,200 square feet, a capacity of 1,650 cubic feet per minute is recommended.
- Attic fans can be automatically actuated by a thermostat to reduce high temperatures in summer and a humidistat to exhaust humid air in winter.
For nearly 40 years, Donald P. Dick Air Conditioning has provided the latest HVAC technology to homeowners in the central San Joaquin valley. Give us a call. We’re here with more energy-saving suggestions for all-year comfort.
Our goal is to help educate our customers in the greater Fresno, California area about energy and home comfort issues (specific to HVAC systems). For more information about attic fans and other HVAC topics, download our free Home Comfort Resource guide.
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