The first, Type I, is the most common. It is a 20” to 36” diameter fan, either a direct drive or belt driven assembly that mounts to the ceiling on the attic side. It requires a large cutout in the ceiling and uses a moveable louver grill to cover the hole in the ceiling. They move a large volume of air (3,000 to 9,000 cfm) and do an excellent job of cooling and ventilating a house Their main advantage is that they are the least expensive to purchase; but they have many disadvantages such as:

1. They can be difficult and expensive to install.
2. They are very noisy in operation.
3. It can be difficult or impossible to find an ideal location for them in many homes.
4. They do not cool or ventilate an individual room when the room door is closed.
5. They offer little thermal insulation protection in cold climates in winter.
6. Belt drive models require periodic maintenance.
7. They appear unattractive in the ceiling.

1. They are the most expensive to purchase.
2. Their noise level, less than most Type I whole house fans, is still a bothersome whine and is unacceptable to most people while viewing television or sleeping.
3. They provide very little cooling or ventilation in a timely manner when installed as recommended by the manufacturer.
4. They are inexpensive per hour to operate, but require many hours of run time to accomplish their purpose.
5. They do require some carpentry framing modification to install.

The third, Type III, is a QUIETCOOL QC-1500. (U.S. Patent Pending) It is an innovative whole house fan that has none of the disadvantages of Type I and Type II.

It’s big advantage is that it is not mounted to the ceiling but instead is suspended in the attic with straps from the roof rafters. It’s connected to an attractive ceiling grill with a flexible accoustical insulated duct, thus eliminating all vibration, rattle and noise in the house. It is so quiet in operation that it can be installed in a bedroom or sleeping room without a sleeping person being able to hear it.

This cleverly engineered system can be installed almost anywhere in a ceiling or vertical wall in less than 1/3 the time it takes to install a Type I or Type II whole house fan. It has a damper with insulated doors that prevents cold air intrusion in the wintertime. One QC-1500 performs better than one Type II whole house fan in all respects, but we recommend that one QC-1500 be installed for each 500 Sq. ft. of living space (ideally one per bedroom) to obtain the cooling breeze of a type I whole house fan. This also allows the cooling and ventilation to take affect even with the bedroom door closed as long as a window is open.