QA-Deluxe 6500 energy-efficient fan is for 2-story homes up to 4400 sqft & single story homes up to 3000 sqft and requires about 5.5 sqft of net free attic ventilation.

QA-Deluxe 5500 insulated whole house fan is for 2-story homes up to 3400 sqft and single-story homes up to 2400 sqft, and requires about 4.5 sqft of net free attic ventilation.

QA-Deluxe 4800 high-efficiency whole house fan is for 2-story homes up to 2800 sqft & single story homes up to 1900 sqft and requires about 4.0 sqft of net free attic ventilation. It uses of an energy saving (ECM) electronically commutated motor.

QA-Deluxe 3300 is for 2-story homes up to 1450 sqft & single story homes up to 900 sqft and requires about 2.5 sqft of net free attic ventilation. It uses of a highly reliable (PSC) permanent split capacitor motor.