Common Bath Fan Terms

Amperage (amps)- is a measurement of the amount of electric charge passing a point in an electric circuit per unit time. In layman's terms, more amps usually equal more power.

CFM (cubic feet per minute)- is a measurement of the volume of air a fan can move. More CFM means a better capacity for ventilation. Typical bathroom fan can be 80-110 cfm. HVI recommends 1 CFM per square foot (assuming 8 ft. ceilings)

Example: A 10 x 10 foot bathroom with an 8 ft. ceiling height = 100 squarfeet. A 100 CFM fan is recommended

Sone- is a measurement of the sound coming from an exhaust fan. The lower the sone, the quieter the fan.

 Duct Size- is the measurement of the diameter of the fan duct. 4” is pretty standard up to 110 cfm. Anything larger than 110 cfm increases to 6”duct.

Elbows will reduce fan performance and increase noise

•       Avoid elbows and bends whenever possible

•       Avoid a 90 degree elbow immediately off the duct connector. An installation that has a 90-degree elbow immediately after the fan exhaust port will cause air to flow back into the fan.

–      Allow a 2-3 foot straight run out of the fan before the first elbow.  This allows airflow momentum to build before passing through the first elbow.

–      Use a long radius angle to help ensure optimum airflow and minimum airflow noise.

–      BEST material to use to install is Galvanized rigid pipe or PVC

–      BETTER material is aluminum flex

–      POOR material to use is vinyl or dryer vent.  This type of material is never    recommended because it will cause the worst static pressure and create excessive noise

–      Always choose the shortest length

–      Always choose a smooth, inner surface duct

–      Always choose the straightest duct run

–      Avoid any sagging or weaving in the duct run

Exhaust Fan- is a fan typically found in a bathroom area that pulls air out of an area, removing moisture and odors. Ideal fan location is within the tub/shower space. Most fans and fan light are rated for damp locations.

Two types of ventilation

·      Continuous run (whole house) ventilation (Indoor Air Quality):

Used to remove stale air and provide fresh air on a slow continuous basis.

·      Intermittent (spot) ventilation:

Used to remove moisture and pollutants quickly at the source.

Ø  bathroom exhaust for shower or tub

Ø  range hood over the stove

Ø  utility room, work shop and home office task areas

In Line Fan- is an exhaust fan that is installed in the attic area, reducing noise from the fan. Multiple rooms can be ventilated using one fan and numerous ports.

 UL Listed is the certification from an independent organization that establishes standards for different product categories. Products are tested to make sure they meet certain standards. In the case of bath fans, the UL seal ensures that your fan is safe to operate in the bath environment.

 Energy Star is a division of the EPA and is a certification that takes in consideration cfm per watt ratio.

 Voltage (volts)-120 volts is the standard for bath fans in the U.S.

 Air Changes or Exchanges - The amount of time, expressed in minutes, that is takes for a fan system to replace air in an area.

Circulation - The process of a fan moving air around within a specific area.

Static Pressure - The amount of resistance in a circulation or ventilation system that a fan must surmount to ensure proper air movement. Most fans are tested at .1SP and the premium fans can go as high as .375 SP.

Ventilation - The fan process in which air is moved into, out of and between different areas. Ventilation is used to replace old, stale, odiferous or contaminated air with fresher, cleaner air.