Good Dryer Venting Information

Here’s a manufacture table:

Maximum Vent Length with 90° elbows

Example: GE (6.0+ capacity electric models)

Rigid Metal- Hood Type-A 90 ft. 60 ft. 45 ft. 35 ft. 25 ft.

As an inspector when I’m in a home without a dryer present I cannot comment on whether or not the run is acceptable; but i can comment on it’s ‘legality’ as interpreted by the local AHJ’s. This I can do without knowing the dryer to be installed in the home.

As a builder I simply put the laundry on a exterior wall and run a 8 inch transition duct to a three flap termination… but that’s just me…:mrgreen:

Now if I were to build one like I’ve encountered on inspections, I would certainly notify the buyer of the need for an appliance which will safely handle the additional run (providing I “got away with it” in the first place) but that doesn’t help the subsequent buyers of the home.

A particular installation may exceed IRC requirememt if it is still within the minimum requirement recommended by the appliance manufacturer and accepted as an approved installation by the AHJ.

A Dryer Vent exhaust run that exceeds 25 feet (without a Dryer present) should be noted as an excessive run.

Determination of code compliance can only be made based upon the Dryer to be installed.

Good table for different manufacturers…

I know this is an old thread but can anyone tell me if the 2009 IRC makes ANY exception on maximum length of run if a 5 inch vent pipe is used?

I don’t have a 2009 IRC but the section should be M1501.

No exceptions John and under the fitting equivalent length calculations, 5" is not listed.
They have 4",6",8"and 10". Still at 25’ maximum for length of exhaust or as listed by the Manufacturers instructions. :slight_smile:

Thanks Marcel. :wink:

Some of the Builders in this area have done the same…
where the length of the run exceeds 25 feet, they increase the size of the vent piping (usually 6 inch here)…
A Residential Dryer Blower is rated and sized at 4 inch. Increasing the size of the piping actually makes the situation worse as the velocity of the air is reduced over the length of the excessive run. Dryer Lint will accumulate at an accelerated rate.

As a side note…
A Recent Fire in Malvern PA…
40 Foot Dryer vent run with multiple elbows (4 - 6)
9 year old home…

True Joe, but is it not why they have invented in line fan blowers for that application?
Just saying. :slight_smile:

Interesting photos Joe.
40’, Wow. No common sense on that one. :slight_smile:

But most Builders do not install the inline fan properly either…
Reading the installation manual seems to escape so many…