Hi Guys
I know the dryer vents specs (lenght, diameter,) what i want to know is; does the 25 feet (-5 feet per 90*) apply to other vents like : bathroom and kitchens.
First, you need to know that some manufacturers have different specs for their dryer vents and it is their specs that take precedent over the code. Your figures are not right in every instance.
Second, think about why there is a maximum length. What is it there for? That will help you in answering your own question.
Bathroom and kitchen vents simply need to vent to the outdoors.
great info jeff!
Even though it doesn’t exactly address your question, I thought it may be useful. I do mostly agree with Jim’s comment, but not 100%. Although there is no actual ‘code’ or specific ‘specs’, there are ‘best practices’ regarding air movement. I haven’t (yet) found my file that has more specific info, similar to dryer venting, (rigid smooth wall ducts, etc…) but I will post it if/when I locate it.
And for your benefit Jim, no, I wouldn’t call out a bathroon fan vent that was utilizing plastic accordian style, unless, it was kinked or a very extended run.
I commonly see (and write up as a material defect) bathrooms and kitchen vents exiting at the soffit where soffits are being used to draw air for attic ventilation. It doesn’t matter how smoothe they are or how many bends they have in those instances. After that, as long as the moisture is leaving the building, I’m okay with it.
· Improve: We noted that the exhaust duct for the main floor bathroom fan discharges the air through the roof soffit. This can promote mould growth in the roof space as a result of air flowing from the soffit into the roof space. It is better to run the exhaust duct through a gable end in the roof space or through a wall or roof. Equip the duct with a backdraft damper provided with weather-stripping and a counterweight or spring to prevent air return (“Clapet Daoust” type of damper or equivalent). Ensure that the exhaust outlet is not blocked, that the backdraft damper is working and closes properly, and that the air is discharged directly to the outside through a sealed, insulated duct. Make certain that duct is the size recommended by the manufacturer and is a short and straight as possible. Seal all leaks.