2

I'm replacing a gas dryer in a condo that previously had 2 plastic flex pipes and a 5ft aluminum rigid duct.

I planned to replace it with rigid steel. I got most of it dry-fitted correctly, except the end of the run. There's about 2 feet between my new run and the exterior vent. See side-view image below (note: the picture does not show that the exterior vent is a little lower and also to the right):

enter image description here

The end of the run is in a tight area, in a small 3x3 closet that also contains a circuit breaker. To get through here with rigid steel ducts, I'll need several elbows and short extenders. I'd rather use a bit of semi-rigid flex vent in a small C-shape instead, for ease of installation and less seams.

The red dashed line in my picture represents where the flex duct would go. It would be about 2 to 2.5 feet long.

  1. Is it OK to use flex duct near the end of a run at this length (about 18 ft total)?

  2. (More generally) If a duct is going to require several quick bends and seams in a tight area, is it ever better to use a single flexible duct instead? If yes, how should that determination be made?

Edit: I ended up admitting to myself that I was trying to be lazy and fanangled a few adjustable elbows to cover this gap. I'd still like to know the answer to #2.

Improve this question
4
  • How high up on the wall is the vent terminus?
    – ThreePhaseEel
    Apr 4, 2018 at 22:51
  • About 6'9". My run is going between 2 joists; the terminal vent is just under the joints
    – Scribblemacher
    Apr 4, 2018 at 23:09
  • Is the vent exiting directly above or to the left of the circuit breaker?
    – mikes
    Apr 5, 2018 at 0:02
  • The vent is beside it, to the right. It's going out a window at that location (the glass was replaced with sheet metal)
    – Scribblemacher
    Apr 5, 2018 at 11:04

1 Answer 1

Reset to default
1

The drier installation instructions should typically have venting parameters that should be followed. That being said, rigid duct will always flow more air than corrugated flexible aluminum tubing. 4” aluminum flexible tubing flows approximately the same air as 3” hard pipe. All of the little ridges slow down air flow significantly. While a few feet of flexible tubing will probably not drastically reduce air flow I would always avoid it if at all possible. The less resistance the faster your cloths will dry.

Improve this answer
1
  • The instructions said "rigid only" and provided maximum lengths and elbows (I think most/all gas dryers tell you not to use flex duct though because of CO). Your 4" rigid to 3" flex "conversion" is helpful for understanding what using flex in this case would do to the run.
    – Scribblemacher
    Apr 6, 2018 at 13:02

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.