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length of a dryer vent

I want to replace my flexible aluminium dryer vent hose with a rigid metal vent hose. how many right angle turns are you allowed? I need to cover a distance of 10 feet and i have 4 right angle turns (2 right turns, 1 turn going vertical and the last turn o go back to horizontal). i can't move the dryer to get it closer to the vent because of the gas pipe.

Re: length of a dryer vent

Good to hear you are using the rigid ducting.

Every 90 degree elbow adds restriction approx. 4-5 feet of equivalent length to the duct. So in theory that would add approx. 16-20 feet of ducting to the 10 feet you have to go equaling around 26-30 of equivalent distance.... which is around the maximum from a dryer.

If you can make the elbows less than 90 degrees it will help reduce the restrictions.

Hope this helps.:)

Cardiac Paul
Re: length of a dryer vent

You can make the last two elbows into 45s with a lenth between them. also don't forget to factor in the first 90 out the rear of the dryer.

Re: length of a dryer vent

Codewise, the limit is 25 equivalent feet, meaning that you add the measured length to the fitting equivalants. So, on a measured length of 10 feet, you could have 3 90 degree elbows on the vent.

However, the code also adds that, if the dryer manufacturer's installation instructions allow longer lengths and more elbows, you can go with that.

Nearly every manufacturer would allow the setup you have, and even more. But check your installation manual to be sure.

Timothy Miller
Re: length of a dryer vent

Great time to consider adding a secondary lint trap into the exhaust duct . Really helpful in long pipe runs to stop build up of lint and reducing fire potential...

Re: length of a dryer vent

Does anyone know what the code is on this? It seems that I always am getting in trouble for this and can NEVER get enough info on it :(

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