9: Bathroom Exhaust Fan Maximum Duct Length

Im renovating my bathroom and plan to install a fan. Can i vent my bathroom exhaust fan into a plumbing drain vent.

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Domestic axial fans an axial fan has a fan blade like a ship propeller.

Bathroom exhaust fan maximum duct length. Vent fans are rated by the number of cubic feet of air they move per minute cfm and its important to buy a large enough fan for the size of your bathroom. Decreasing the design flow rate increases the acceptable duct length. Bathroom vent fans serve an important function by removing humid air from your home to prevent mold and mildew from forming.

What is the maximum duct length from a bathroom fan. Our bathroom extractor fans are vented into the attic of our 70yr old house in philadelphia. These are low pressure fans and a general rule of thumb for these is to use no more than 15 metres of ducting.

Title 24 requirement ashrae 622 2007 ashrae 622 2010. Ask question asked 4 years. The duct in this case would be the same temperature as the ambient air since there is no heat source present to insulate.

In the case bathroom exhaust there will be warm humid air. When designing ducting for local exhaust ventilation use the prescriptive duct chart. If we were to insulate the duct in this case it would still be the same temperature as the uninsulated duct since there is no heat source to insulate.

Maximum length for bathroom extractorexhaust fan vent. Maximum length for bathroom extractorexhaust fan vent. Here we provide specifications for recommended minimum maximum duct lengths for bathroom vent fans.

The shower is on one side of the room and the bath is on the opposite wall so i plan to put the fan in the middle of the room. North americas largest producer of residential ventilation products such as kitchen exhaust range hoods bathroom exhaust ventilation fans and whole house fresh air systems. Bath fans and kitchen range hoods can be sized prescriptively.

Maximum duct length calculator. To accomplish this youll have to select a fan based on the size of the bathroom and the equivalent duct length. The first thing youll have to figure is the size of the bathroom.

A common question and the guidance below is more relevant to domestic type installations. Bathroom exhaust fan duct length specifications. Duct length is calculated with the same formulas used to develop 2015 irc table m15062 and 2018 irc.

A bath vent fan duct that is too long may restrict air flow such that the fan is not functional. A bath vent fan duct that is too short may violate the manufacturers installation instructions may not work properly or may be drafty. Design the duct system.

On a 100mm fanducting system a 90 degree bend is equivalent to 1 metre preferably rigid duct. Maximum length in feet fan rating in cfm certified at 025 in. Is 20 feet too long to run bathroom fan duct for 100cfm fan.

Decreasing the design flow rate increases the acceptable duct length. According to our home energy auditor this is pretty common here.