flex versus alum or steel

niceguy525 · 11-03-2011, 11:24 PM

I was considering replacing the "flex" tubing/duct work that goes from my central air unit to my daughters bedroom with regular aluminum/steel duct work that could be wrapped with more insulation. Her bedroom only has one inside wall and consequently is the coldest room in the house. Is there any advantage to "traditional" duct work over "flex"? Also, is it possible to wire a step-up fan into the duct to help with the circulation. There is probably a 30 ft. run from the main unit to the bedroom. Is this done commonly? Can an extra fan be wired to activate when the central unit comes on?

DannyT · 11-03-2011, 11:50 PM

regular ductwork will work much better then the flex because there is less resistance to the air flow since its smooth on the inside. you should be able to wire a booster fan in the line. i'm sure someone with more electrical experience than me will be along to tell you how to do it.

REP · 11-04-2011, 01:40 AM

You can pick up sometimes 25% more cfms with hard duct.Depending on the size of the room you may even want to increase the size of the duct.
Now why do I get the feeling that there is no return air grille in that room?You may have to leave the bedroom door open if there is no return air grille.
Cutting a gap in the bottom of the door rarely works good.
Fans like the one you are talking about are loud especially when you are trying to get to sleep,create drafts,and rarely provide comfort.

COLDIRON · 11-04-2011, 07:26 AM

If your just adding an additional run to a bedroom off the main I would recommend running flex, it's the easiest for a DIYER and you can bend it around obstacles and it don't have to be an exact length. One run off a main system makes no difference, many states in warm climates that's all they run in attics.

biggles · 11-04-2011, 08:25 AM

if the walls get chilled out in the winter you need to insulate first. you need to hold what heat is going in then see what needs to be done.might consider a duct heater with a seperate stat and the fan add on.might consider adding a return back to the actual furnace would pull some of the chill out