When determining the fan type, many things need to be considered: the location-indoor or outdoor, mounting type such as roof curb, sidewall, hanging, the airflow type-exhaust, supply, or recirculation and airstream conditions-general clean air or contaminated air.

Fans located indoors can be ducted to the outside, or can circulate air in the building. Fans located outdoors need special considerations to protect the fan and building from the elements. The fan’s construction needs to be designed to prevent water or rain penetration back into the building. Motors, bearings and drives need to beprotected from rain, snow and temperature extremes.

Once the mounting lcoation has been determined there are a number of mounting types for each locaiton. Indoor mounting types include: on or in a wall, in the ceiling, hanging or suspended from the ceiling, portable or free standing or mounted in a plenum. Outdoor mounting types include:roof curb, equipment supports and mounted directly to the roof or wall of the building.

The next step is to identify the airflow type. Airflow types are: exhaust, which moves air from inside the building to the outside; supply, which moves outside air into the building; reversible, which can provide either supply or exhaust air or recirculating units which provide air movement from within the building.

Airstream conditions may also be classified by application type. The major catagories are general clean air and contaminated air. Examples of clean air applications include offices, bathrooms, factories, warehouses, temperatures below 180 degrees Fahrenheit, and low moisture. Examples of contaminated air include grease laden, as found in restaurants and kitchens, fume hood exhaust, found in laboratories, explosive, temperature above 180 degrees Fahrenheit, emergency smoke control, process ventialtion, dust, and particulates.

To recap, when selecting a fan type, consider: location, mounting, airflow and airstream conditions.