Premium Choice Bathroom Fan Metal Grille Kit With Radiation Damper Manual

Bathroom Fan Sizing

The following recommendations follow the Home Ventilating Institute (HVI) guidelines:

Fan Sizing for Bathrooms Under 100 Square Feet

The standard rule for bathrooms 100 square feet or smaller is one CFM per square foot of

the bathroom. To nd the square footage multiply the length of the bathroom by the width.

Example

Bathroom is 9’ x 5’ (with 8’ ceilings). Multiply 9 x 5 = 45 sq. ft.

Bathroom area is 45 sq. ft.

At 1 CFM per square foot the minimum recommendation is a fan rated at least 45 CFM.

Fan Sizing for Bathrooms Over 100 Square Feet

Ventilation for baths over 100 square feet is calculated based

on the xtures in the bathroom (see table to right). Add the CFM

for all xtures and you’ll have the total CFM required for the

bathroom.

Note: Enclosed toilet rooms must have an operable window or a fan for ventilation.

Example

The bathroom is 20’ x 12’. There is a tub (without jets), a shower and a toilet.

Calculation: 1 Toilet +1 Shower +1 Tub =150 CFM

Two Solution Options:

1. Install a 50 CFM fan over the tub, one in the shower and in the water closet. This

method is very effective and will provide ventilation where and when it’s needed.

2. Install one 150 CFM fan. The air will then be pulled through the entire room and

exhausted at a central location.

Duration of Ventilation

HVI recommends that the fan be left on for 20 minutes after use of the bathroom. A timer

is a good solution, allowing the fan to turn off automatically at the proper time. For steam

showers it is best to have a separate fan in the steam room that can be turned on after

use.

Continuous Ventilation

Ventilation may also be provided on a continuous basis at other rates. This may

complement the use of fans to provide the HVI recommended rates.

For more information on bath fan sizing and ventilation visit www.hvi.org.

Toilet 50 CFM

Shower 50 CFM

Bath Tub 50 CFM

Jetted Tub 100 CFM