Frequently Asked Questions

A whole house fan is a large propeller fan that sits on the floor of your attic. It's framed in with lumber, and a hole is cut through the ceiling directly under the fan. A white shutter is placed in the hole, opening automatically when the fan runs and closing when it's off.

When you open windows and turn on the fan, it draws air into the house, creating a breeze, removes the hot air in its path, blows that air into the attic, and then pushes the super-heated attic air out through the roof vents. The result: your home cools down naturally.

Whole house fan: Mounted in your ceiling, creates airflow through your entire home, pulls in cool outside air, and pushes hot air out. Cools your living space directly.

Attic exhaust fan (powered vent): Mounted on the roof or gable, only removes hot air from the attic. Turns on automatically via thermostat. Does not create a breeze through your home or remove hot air from your living space.

In homes with flat 8-9 foot ceilings and existing AC, an attic exhaust fan might reduce room temperature by about 5°F. But if you want to actually cool your home, create airflow, or significantly reduce AC usage, you need a whole house fan.

A whole house fan uses about 200-400 watts, similar to 2-4 light bulbs. That's a fraction of what air conditioning costs.

An attic exhaust fan uses even less, about 50-75 watts, though it runs longer (6-12 hours daily in summer).

Yes, always. The fan needs air to pull in. Without open windows, the fan creates a vacuum effect, runs louder, moves less air, and won't cool your home effectively.

Open windows equal to or greater than the size of the ceiling shutter. For most installations, this means 2-5 windows depending on fan size.

Run the fan when outside air is cooler than inside air. In Colorado summers, this is typically after 6-7pm.

For best results, run the fan overnight (8pm to 6am). This cools not just the air but also the walls, floors, and furniture, which then stay cool well into the next afternoon.

No. Never run the whole house fan and air conditioner simultaneously. The fan would exhaust the expensive cooled air you just paid for. Use one or the other, not both.

No. There's no "blizzard" of insulation when you turn on the fan. Everything appears perfectly still in the attic. If you put your hand over the running fan you'll feel air moving upward, but apart from that, there's no visible air movement until you reach the exhaust vents.

A whole house fan is probably the only economical solution to this problem. Remember basic physics: hot air rises, cold air falls. That's why AC struggles to cool upper levels.

A whole house fan blows out the concentrated hot air upstairs and the super-heated attic air, reducing the load on your AC. On many days, you can eliminate the need for AC altogether. On the hottest days, the fan pre-cools your home so AC runs less.

Belt drive fans transmit power from motor to blade via an automotive-style belt. This allows larger blades to spin more slowly, resulting in quieter operation. They use standard motors that can be easily replaced if needed.

Direct drive fans have the blade attached directly to the motor. Since it's difficult to design motors that spin slowly, these fans typically use smaller, flatter blades that spin fast, making them noisier. Motors are often custom-mounted, making replacement difficult or impossible.

Solar attic exhaust fans have significant limitations:

• They spin at top speed only in bright sun. Clouds, evening, and darkness slow or stop them
• Even at top speed, they move about half as much air as a standard electric attic exhaust fan
• A standard electric attic exhaust fan costs only $5-10 per year to operate

More importantly, with modern insulation (8-16 inches), attic heat rarely penetrates to affect room temperature significantly. The primary benefit of attic exhaust fans is psychological, making homeowners feel good about "going solar."

If you want to actually cool your home, you need a whole house fan, not an attic exhaust fan of any type.

Probably not, but it won't hurt. You can use the whole house fan to blow hot air out of the attic anytime. If you don't want a breeze through the entire house, just open one window near the fan and run it briefly.

Some customers add a roof-mounted power vent for automatic operation and additional ventilation (each provides about 1 sq ft of venting).

Fan size depends on your home's square footage (not counting basement):

• 30" fan: Homes under 1,800 sq ft
• 36" fan: Homes 1,800 to 3,000 sq ft
• 42" fan: Homes 3,000 to 4,000+ sq ft

Why we do not count the basement: Basements in Colorado stay naturally cool because they are underground. The whole house fan pulls air from the main living areas and upper floors where the heat accumulates. Cool basement air naturally rises to replace the hot air being exhausted, so the basement benefits from the fan without needing to be factored into the sizing calculation.

For extra quiet operation, consider installing a larger fan and running it on low speed. You will get the same airflow as a smaller fan on high speed, but quieter.

Almost certainly yes, if you're in Colorado. Most Colorado attics have only 2-3 sq ft of ventilation, when a whole house fan needs 4-9 sq ft to run at full efficiency.

Without enough ventilation, air backs up in the attic and pushes against the fan, causing reduced airflow, increased noise, and premature wear.

The fan will still work with inadequate ventilation, just not as well as it could. It's like driving with the parking brake partially engaged.

Learn more about attic ventilation →

Attic ventilation is designed to prevent moisture damage, not to cool attics. In humid climates, builders install plenty of venting to prevent condensation and mold.

But Colorado is very dry. Since moisture damage isn't a concern here, builders routinely skimp on attic ventilation. This causes no problems for the home, but it's inadequate for whole house fan operation.

No. Only the total square footage of venting matters. Whether vents are on the ridge, roof surface, gables, or soffits makes no difference. The fan will blow air out regardless of where the vents are located, as long as the air path isn't blocked.

No. A properly engineered, properly installed whole house fan with adequate ventilation runs quietly at 46-52 decibels on high speed. You can have a normal conversation standing directly under the fan. On low speed, you can whisper.

Noise problems are typically caused by:

• Cheap, poorly engineered fans (common at big box stores)
• Flimsy shutters that rattle in the airflow
• Inadequate attic ventilation causing backpressure
• Poor installation with loose screws or improper mounting
• Worn or cracked belts (easy to replace)

Quick test: Remove the attic entry hatch and run the fan (put down a tarp to catch any insulation). If it's noticeably quieter, your attic is under-ventilated. Adding vents will help.

Other solutions:

• Replace a flimsy shutter with a heavy-duty, spring-loaded model
• Check for and replace cracked or worn belts
• Tighten all screws and bolts, especially on pulleys and motor mounting
• Ensure rubber isolation mounts are in place

If the fan is inherently poorly designed (small fast-spinning blades), the only real solution is replacement with a quality fan.

Many fans marketed as "whole house fans" online don't move enough air to deserve the name. They move 1,000-2,500 CFM, which isn't enough to cool most homes. You'd need 3-4 of them to match what one of our fans does.

Some are quiet because they're hidden in the attic with tubes to ceiling grates. But they solve a noise problem that doesn't exist. A quality belt-drive fan is already extremely quiet when properly installed with adequate ventilation.

Also consider: Will parts be available in 10 years? Will anyone know how to repair these exotic designs? Our fans use standard components that have been available for decades and will be available for decades more.