What I have to work with is this: clothes dryer backs up to an interior wall, framed in 2x4s. The floor is over an exterior soffit; i.e., dropping straight down through the floor joists, we go then through soffit framing, the face (exterior ceiling) is finished in 5/8″ e&cb fir beadboard. I can run ducting straight down and shortly be outside, but at a soffit exit, not a vertical wall exit.
First question: how do you squeeze those duct fittings for dryer venting into a 2×4 wall frame.
Second: what products are available to prevent backdraft in a dryer vent line that exits through a soffit? I have used “flap grilles” in vertical wall vent situations, but they will just fall open and stay open in a soffit.
Replies
Interesting dilema. As the fittings and hoses are all 4" diameter, I'm not sure how you're gonna squeeze them thru a 3.5" plate, which implies separation of the plate altogether.
If you do find a way, you may be necking down the duct work such that the restriction in flow (in conjunction with the requirement of hot air flowing straight down) is such that the operation of the dryer may be adversely affected. I've seen plastic hoses crushed when the dryer was pushed in, and the people did a head-slap when the situation was explained to them. They said that they have never gotten dry clothes without running the unit for an hour or more.
I have used an in-line device for reverse flow and critter blockage, but it is no more than an enclosed variety of the shutter type damper you're familiar with, and must be installed on a horizontal run.
If you absolutely must go down thru the soffit via the 2x4 wall, you can probably find a 4" to 3" aluminum adapter at HD. Look in the duct section in plumbing. Put the adapter on as close to the floor as possible to minimize the 3" run, then duct it into the wall and down.
Is there any way you can put it thru the floor without going thru the wall? Or am I missing the big picture? How much soffit is available? If possible, send the exhaust straight down thru the floor to the soffit.
Whichever method you use, think about constructing a box that attaches to the soffit that the duct terminates into, with your standard flapper directing the exhaust out away from the wall. Dryer exhaust is loaded with moisture, and just dumping it under the soffit is asking for moisture problems in the immediate vacinity later on. Paint curling, mold, mildew, dryrot, whatever.
Sorry this is so long. I'm laid up and have nothing else to do.
Good luck.
Hey, Nick, laid up, eh? Too bad. But thanks for your reply.
I looked into this a little more by using Google. Dryer Vent Box makes one for a 2x4 wall that has the hole for the duct being oval and not round. It looks like I can squeeze some round foil-clad flexible duct into an oval cross section that will make it in my 3-1/2" stud cavity.
I found a soffit vent fitting that I think will work for me.
As for going through the wall plate and leaving nothing where the cut is, I am not concerned. The wall is a non-bearing interior wall. I have seen lots of total plate cut throughs when HVAC contractors run supply and return air ducts in the stud spaces of walls.
Thanks for the reply. That's nice info to have should I run into the same problem.
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