Selecting a System


A zoned whole house fan for a Hawaii home

Zoned or Central? 

The first task is to determine the number of units that you will need based on your lifestyle and layout.

Central (single-unit) system

A centrally installed system is one large unit installed in the top and central location in the home.  This is usually the center of a single story, or at the top of the stairs in a two-story home. A single QuietCool system is strong enough to nicely ventilate an average home, and is a good choice for smaller households or homeowners on a budget.

Zoned (Multi-unit) system

A multi-unit zoned system gives the homeowner maximum control over their ventilation and cooling needs. When sizing a zoned system, the combined CFM (cubic air flow per minute) of all zoned units (not each individual unit) needs to match or exceed the total CFM requirements. All zoned fans can be turned on simultaneously when the entire home needs to be cooled, but a zoned system also allows individual area control. For example, if you’re going to bed at night, rather then running the central system, turn on the bedroom unit only.

Layout Considerations

While a square shaped living space usually has only a single system, L-shaped or large rooms with multiple living areas can benefit from multiple smaller units.

Sizing Formula

To determine the size of the equipment you will need to calculate the square footage of your rooms and multiply by the height of the ceiling. This is the volume of your home. Hawaii systems are sized for a complete air exchange of that volume in 2-3 minutes or less.

For Hawaii homes we recommend:

  • 1500 CFM (QC/ES) Unit for a standard bedroom
  • 2250 CFM Units for a master bedroom
  • 3100 CFM Units for a living space of 600-900 square feet
  • 4700 CFM Units for a whole home area of 900-1600 square feet
  • 5400 CFM Units for a whole home area of 1600-2400 square feet

Attic Venting

Each units needs 1 square foot of net free venting per 750 CFM.  (A 4500 CFM system would need 6 square feet of venting).  The attic venting you choose will be specific to your home and roof type. Homeowners can increase their venting by adding gable, ridge, roof top or soffit vents.

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