Bathroom Exhaust Fan Vent Pipe Size

The basics of venting a bathroom exhaust fan.

Bathroom exhaust fan vent pipe size.

25 8 200 cfm rated vent fan. For example a 10 wide by 15 long bathroom with a 10 ceiling would need. This section discusses the minimum exhaust capacity of the exhaust fan. The bathroom has a separate toilet room.

A 3 or 4 inch duct connects to the outlet on the fan housing and runs to a side wall or to the roof and connects to a vent cap that allows the exhaust to disperse outdoors. If your bathroom has a higher ceiling multiply the width x length x height of the room divide by 60 minutes in an hour then multiply by 8 number of air exchanges per hour. 1500 60 25. 50 cubic feet per minute cfm intermittent or 20 cfm continuous.

Why your bathroom should have an exhausting vent fan bathroom venting fans are about more than just eliminating noxious odors. 3 x 320 cfm 960 cfm to be vented. A diameter of 4 inches is common for exhaust ducts but some high cfm fans fit a 6 inch diameter duct. 100 cfm fan with a 4 exhaust port and back flow flap.

The bathroom exhaust ventilation fan disperses air through an opening in the fan housing which is usually 3 inches in diameter and ideally faces in the direction of the ventilation system outlet. Your inline exhaust fan has to thus be have a 960 cfm capacity before allowing for losses due to duct size bends material restrictions in air flow and duct length. For that air volume 8 diameter vent ducts are close to their limit and 10 is indeed preferable. Required bathroom vent fan ventilation rate in cfm this ventilation code specifies a bathroom exhaust airflow rate for toilet rooms and bathrooms not served by a window of adequate size of 25 or 50 cfm ft for hotels motels resorts and dormitories and a slightly more modest 20 50 cfm for private dwellings.

Sizing for large bathrooms for bathrooms over 100 square feet exhaust fans can be sized according to the number of fixtures in the room. If i can find a y pipe with a 4 and a 6 entry what size should the exit pipe be. You can upgrade to a larger diameter duct for greater efficiency or you can use an adapter reducer often included with the fan to fit the smaller duct.