Can I put a dryer vent duct under a concrete slab?

[timswi]

Sooner or later this vent will need maintenance or repair.

I think you will be far better off to run it up through a 6" stud wall and out through the attic.

True..I don't know how that wouldn't condinsate and turn any lint dust into a giant piece of solidified something...Guess raidiant heat (if installed) might help, but hot hitting a cold is a guranteed water generator under concrete...I'd try something overhead and out personally.

 

[Tractor Seabee]

As long as you are exiting well above grade and you slope at least 1/4 to 1/2 inch/ft of run it should drain out the condensate. Steel or alum pipe will rust/corrode out very fast so do not use unless you want to chop up the concrete in 5 years and redo. I would use PVC Sched 40. Plan on cleaning out the lint reguarly as the wet lint will ball up fast and clog. that will raise the dryer temp to the limit cut-out quick. Your solution is better than going overhead. A vertical stack and overhead line will be a bigger maintenance pain. All that wet lint and water will accumulate at the bottom of the riser and plug up fast as the wet lint will not move vertically worth a diddley. I have done vertical and overhead solutions for commercial dyers and we had to have a means to cool the air rapidly to drop ot the water, drain it to a floor drain and provide a cleanout at every turn, to meet code. Apply for a permit for either of the mentioned solutions and you will probabaly wish the dryer was next to an outside wall. Inspectors love to write up these non-conforming solutions (in their narrow minds) as they are not familiar with the physics involved in any of what they do. Be sure and put the hood and flapper unit on the exit end to keep out the rodents. You will get more bugs the closer you are to the ground with the outlet.

Ron

 

[RSKY]

I put mine in the slab. Just be sure it slopes so you can put a garden hose in and flush lint out of it. I used the thickest PVC pipe available and have had no problems in 15 years. With our very large LG dryer I had to get rid of the flexible connector hose and put solid pipe to connect the PVC with the dryer.

 

[CurlyDave]

True..I don't know how that wouldn't condinsate and turn any lint dust into a giant piece of solidified something...Guess raidiant heat (if installed) might help, but hot hitting a cold is a guranteed water generator under concrete...I'd try something overhead and out personally.

If you insulate the part of the vent going up, it will not condense in that section. Slope the rest of the run downhill and you will be OK.

 

[timswi]

If you insulate the part of the vent going up, it will not condense in that section. Slope the rest of the run downhill and you will be OK.

I guess, but that still makes makes me think...Depends on the overall run I guess...I like short runs for dryers...Seems to me that air velocity would die out after 8 or so feet.

 

[ultrarunner]

I've only seen it once...

4" ABS sloped 1/4 per foot to daylight...

Have no idea of code ramifications... been there at last 15 years.

 

[EddieWalker]

I think the main question is where will it come out? Long runs, wether you go up and into the attic, or down, and into the ground, have the common problem of build up. Condensation is going to be more of a location, time of day, season of the year and moisture in the air situation.

I saw on Mike Holmes where they added a clean out to a dryer vent line that went up into the attic. That seemed like a pretty good idea.

Eddie

 

[SandburRanch]

In my earlier reply I failed to mention long radius ells should be used in any pipe line when possible if a turn is necessary. Better flow and easier to clean.

 

[rtimgray]

Thanks for the replies so far.

Running up and out of an attic isn't really a good option, because the addition will be two stories (like the house it is adjoining) with the second floor under roof, so there is no attic to speak of. I could run it between the joists for the second floor, but by the time I go up, over and down, I could be in excess of the 25' rule, to say nothing of the vertical riser and the 90 degree bends.

As with many things on the internet, I've found where dozens of people have done this and have had no problems for many years (using PVC for dryer vent) - that doesn't make it right, it just means it's not unique. I've also found lots of folks warning against it.

Maybe I can find some old asbestos pipe that I could use.....

 

[rtimgray]

...and there would be no problem sloping the pipe/vent to daylight, and it would be a couple of feet off of the ground.