How to Measure for a Wall Fan Vent

How to Measure for a Wall Fan Vent

 

Humid conditions inside of a bathroom or laundry room warrant some type of ventilation fan. Removing trapped heat will make a heating/cooling system more efficient in the summer, while removing trapped humidity will keep mold and mildew from growing. Both of these types of remedies are selling points for a house. This do-it-yourself project can be done in an afternoon.

 

1. Decide where the fan is going to be mounted. In many cases, the fan is connected to the vent by ductwork. The duct work then travels to the side of the wall where the vent will be located. If there is duct work, it will dictate the size of the vent.

 

2. Measure the diameter of the fan if it is to be mounted directly to the wall. In many new installations, a template will be included with the fan. This template can be held against the wall and traced at the point where the fan will be mounted.

 

3. Measure the opening of the duct if the duct will be attached to the vent. Duct size can be different from fan size, particularly if the fan is inside of a fan box. The fan box will contain an outlet hole to which the duct will be attached. In many cases, a smaller duct outlet hole will be used to create more air velocity through the end of the duct, much the way a nozzle creates more water velocity through the end of a hose.

 

4. Measure only the fan opening, on a wall mounted fan, or the duct opening on a ducted fan. The vent measurement will be the equal of either of these holes, and once measured, a vent fan cover can be correctly measured and put into place.