Whole house fans
A whole-house fan is a great piece of equipment, if used and maintained properly. But, what is it, and how does it work?
The whole-house fan is a big fan, installed in the ceiling, normally in a hallway near the bedrooms with an attic space above. To utilize the benefits of the whole-house fan, the windows and/or doors are opened (normally with a screen in place to prevent excess dust and pests from entering), and the fan is turned on. When turned on, the fan moves air from within the house into the attic, where it escapes through the roof vents (ridge vents, gable vents, or turbines). The fan creates a “suction” effect and brings in air from outside through the opened windows and doors.
When would you use this?
These fans are most effective in more temperate climates where there is a temperature swing between daytime temperatures and nighttime temperatures. Think 80s-90s during the day, and 50s-60s at night.
Instead of using the air conditioning system to cool the air in the home, a whole-house fan essentially replaces the warm inside air with cool air from the outside. 15-30 minutes of use can complete almost an entire air exchange, but it is normally recommended to run the fan for longer, sometimes all night, to ensure all interior surfaces have a chance to cool, not just the air.
Why aren’t they used more?
When whole-house fans where more popular, running the air conditioning was expensive! Over the years, air conditioning systems have become more efficient, and technology has improved so that today’s units monitor not only temperature, but also relative humidity as well. Although the air outside may be cooler, if it is overly humid, then you may still feel warm, even at a lower temperature. Today’s systems are likely more efficient if they are used as part of a continuous effort to manage indoor temperature and relative humidity. A whole house fan is definitely a great addition, if used at appropriate times with consideration of humidity levels. If you have one, it is generally advisable to keep it, and use it sparingly. And, of course, keep it maintained.
How do I maintain my whole-house fan?
There are only a few parts to this piece of equipment.
The housing and shroud, and fan blade - This is the frame of the fan, and does not require any maintenance. Ensure nothing is placed on top of the shroud or blades to prevent any damage and ensure proper air flow.
The motor - Not normally serviceable by the homeowner, a quality motor can last 20-40 years or more. When it goes out, it will need to be replaced
The grill and louvers - These are the only barrier between your living space and the attic. Ensure these are cleaned regularly, and ensure they maintain a good seal. Lubricate the pivot points at each end of each louver once a year with a dry silicone.
The belt - These are long-lasting belts, but will eventually degrade, especially with frequent use. Similar to a lawn mower deck belt, when it breaks, replace it. Keep a spare in the attic so you can get it up and running quickly if it does break. When you replace it, order a new spare.
