Codes/Guidelines for use of Flex Duct
I am installing new heating and cooling ductwork in a 1-1/2 story home. The 1st floor has already been completely renovated (including all new ductwork). The supply and return ductwork has been roughed in to the 2nd floor. My friend (a heating and cooling pro) told me to use flex duct behind the knee walls in for the second story. I did use some flex for 2 of the high mount cold air returns for the 1st floor and the inspector said the duct was ok because it was a run of 10′ or less.
Is this a restriction for supply ducts as well or just returns. What are the code limitations for the installation of flex duct. It will be much easier to run the ductwork using the flex duct as some of the areas behind the knee walls are pretty tight.
Looking for some help
Tim Daniel
Replies
Tim-
Depends on the code in your area- in Las Vegas, many of the houses had a small plenum distribution box off the air handler, and the rest of the house was flex- necking down in size as it got further out. here in NJ, 10' is the max you can go with flex, and it has to be supported every 6' minimum.
Bob
Is the 10' limit a local code or from one of the national codes?