Qod 9-9-2010

[Brian E. Kelly]

Originally Posted by gbell

It is great to see so much discussion over what I thought was such a simple question.

Thanks to all of you that participated.

It was a great question Greg, thank you for posting it.

[Marcel R. Cyr]

That's how inventions are made Greg, talking about it.

Big difference on slab living and Basements. Utilities all end up in a basement, and conditions are not allways conducive to the IRC, so other means of adaption are necessary like design around Manufactures specifications and sometimes adding inline fans made for dryer exhaust.

The last condo I inspected the exhaust duct was concealed and the run was about 40' and was disconnected in the wall behind the dryer.
The client was the Assistant Chief of the Fire Department for my Town.

All he said was "Wow".

[Bruce A. King]

On a recent commercial job I saw a 50 foot dryer vent approved on the plans with a certain residential dryer listed. I don't remember the manuf. but it was a residential unit.

[Greg Bell]

I just want to point out that even though there are other options you have to choose what would be the correct answer from the ones available. Many tests given for certification have similar questions that have several answers that are not listed on the test.

[James Smith 6418]

I am a licensed contractor in the state of California. There is the IRC and the IMC. However we are sup post to go by cities codes and the city where i am from goes by CMC. Which is a different company. I have checked other cities and they go by the same. Which is 14 feet Not counting two elbows.Only two elbows are allowed. However when i spoke to the city inspector.He said there is exceptions. The inspector will not pass anything different. Unless You have an engineer sign's off on it. If the engineer signs saying it will work. The inspectors are forced to sign it two. The problem with this is it really does not work for most dryers. Some dryers have really strong air flow and some do not. If you install a venting system for a Maytag (just examples).But that person sells the house and someone uses a roper(just example).That is where there becomes a problem. Where the maintenance costs are higher to maintain that system. Are you have to do a reroute. I find some systems that are signed off.That uses 6 inch and goes 35 to 40 feet. And no dryer will work very well even brand new. I have customers tell me they bought the house brand new. And it took and hour to dry the cloths. That is just wrong. They leave the customer stuck with a problem on a new house. Something needs to be done to stop this from continuing.Thank you and i hope this help.If you have any questions just let me know. I would be glad to help. I work with inspectors in my area to help.

[James A. Levy]

I came up with this:

The International Mechanical Code article 504.6 stipulates the requirements for Domestic clothes dryer ducts. In brief, the maximum length of duct permitted is 25 ft. This maximum length should be reduced by 2.5 ft for each 45-degree bend and 5 ft. for each 90-degree bend. The duct should be a minimum nominal size of 4 inches in diameter and shall have a smooth interior finish.

[Marcel R. Cyr]

Appears the 2009 edition changed it;

504.6.4.1 Specified length.

The maximum length of the
exhaust duct shall be 35 feet (10 668 mm) from the connection
to the transition duct from the dryer to the outlet
terminal. Where fittings are used, the maximum length
of the exhaust duct shall be reduced in accordance with
Table 504.6.4.1

[Brian E. Kelly]

Originally Posted by mcyr

Appears the 2009 edition changed it;

504.6.4.1 Specified length.

The maximum length of the
exhaust duct shall be 35 feet (10 668 mm) from the connection
to the transition duct from the dryer to the outlet
terminal. Where fittings are used, the maximum length
of the exhaust duct shall be reduced in accordance with
Table 504.6.4.1

ahh Marcel, this is not from the IRC my friend.

[Greg Bell]

The correct answer is 25 ft.