Air Conditioning - Should Flex Duct be changed when a/c is replaced?

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bighunk
12-21-05, 05:50 AM
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My gas a/c system is about 17 years old, and I am going to replace it.
Do I automatically replace the flex duct also, or can I use the same ones?

I can't find anything on the Web about the life span of Flex duct.

Thank You

Cajun

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Jay11J
12-21-05, 08:15 AM
The ductwork should be sized to the cfm that the furnace/air handler put out.

The home should have a manual J done, and also manual d to make sure everything will work out for the ductwork.

If the duct is all taped up or water damanged then yes they should replace it.
shank
12-21-05, 03:13 PM
But if your asking if flex duct has a shelf life then I'll just tell you this:

In 1977 my father installed a unit in my grandfathers house and used flex duct. It is still there, and has outlived three units.

Take that for what it is worth.

HVAC
01-01-06, 09:56 PM
I am not a big fan of flex duct for two reasons.

If it is not supported correctly it will restrict air flow.
The air flow on flex is lower then the same size in ridge pipe.


Pete