Defining Exhaust Fans

Exhaust fans play a major role in air quality and temperature controls for residential, commercial, and industrial applications. They work by drawing stale air out of homes and buildings to be replaced with fresh, outdoor air to meet HVAC industry-recommended air quality standards.

Ventilation exhaust fans can help provide a healthful living environment by removing toxic gases, chemicals, and odors. Mold and mildew caused by heat and moisture (particularly in bathrooms, kitchens, and other areas that generate heat and moisture) can cause health problems and compromise the structural integrity of a home or building. Similarly, areas that generate smoke, chemicals, and toxins can be detrimental to health and can cause fires.

Exhaust fans can help to keep building occupants comfortable, safe, and healthy. There are three main types:

• Axial fans (also known as propeller fans) draw air through the fan and are often designed for wall- or ceiling-mounts to cool a space. Roof Mounted fans, variable pitch fans, small cooling fans, and wind turbine fans are examples of axial fans.
• Centrifugal fans (also known as blowers) have a squirrel-cage design and work by drawing air in and exhausting it at a 90-degree angle. They are often noisier than axial fans but are used effectively in air conditioning systems and industrial ventilating and cooling.
• Mixed flow fans look like axial fans with curved blades and can provide air supply and return air under high pressure. They operate with less noise than centrifugal fans.

Exhaust fans can be mounted in an inline system, at the ceiling, on the wall, or on the exterior of a building. They can be used in bathroom ventilation, kitchen range hood exhaust, whole house exhaust, commercial exhaust, and industrial exhaust. In commercial kitchens, exhaust is extremely important for maintaining cleanliness, reducing odor, and maintaining building safety. In industrial settings, exhaust fans can keep workers cool, help provide fresh air, and keep harmful chemicals from causing health and safety problems.