Dryer vent code question

I have a dryer on the first floor which vents directly into the basement via a flexible 4" dia, 4' long transition duct, from there it is 12' to the exterior wall with 2' long, 4" dia solid sections connected with duct tape, where a 90^ elbow connects to another flexible transition duct for about 2' out the basement window. I have to move the current layout of the duct work to accomodate some new plumbing a few floor joists over. I'm trying to find out how many 90^'s I can do with this new layout which totals 24' with 4 90^ elbows if I want it concealed pretty good. I can get away with 3 if needed. The current setup is roughly 18'. I plan on using 2' long, 4" solid sections w/90^ solid elbows and only the flexible duck at the window.

Any help is needed.
Thank you much, BmcNY

I don't think code applies with the question you are asking...with one exception. They usually require the thing to be installed per the manufacturer's instructions. This usually dictates the max length and the max number of angles; it differs manufacturer to manufacturer. Note, though, that the dryer will function better the shorter the vent is and the fewer turns there are. Also, flexible connections (plastic?) collect lint and are not the safest thing as a result. One of the pros can probably give you some averages and maybe some specifics.

Is this gas or electric? What brand?

Yes, the manufacturer will specify how many elbows vs total duct length. The building code here does specify you must have smooth interior wall. The corrugated flex is only allowed at the connection directly out of the dryer.


From a practical standpoint, every foot of pipe and every elbow adds cost and time to each drying load.

Also from the point of view of function, the longer the run of duct is, the more lint build up you'll get. You might have problems with NFPA, on that issue, but the office copy is in another guy's office.