I am replacing a deck with a poured concrete patio.
The problem is that my dryer vents under the deck.
Does any see a problem using standard rigid aluminum ducts to extend
from my house out to the edge of the patio? I will be pouring concrete
on top of the 4" rigid vent.
I have thought of using PVC instead, but I would expect that would be
a hazard were the dust in the vent to ignite.
Missing the patio is not an option, since I would have to route the
vent through several floor joists.
Any better ideas?
It may not be so bad with a straight pipe with no joints, but at some point
it had to come up from under the concrete right? It just has to have some
buildup of lint over time. I see that as being a big problem at some point.
The patio is raised, and the duct would be about two feet higher
the surrounding ground level.
However, after hearing the comments here, I am going to go up through
the ceiling and out the end of the attic. Total run: 25 feet, one 90
degree elbow in the attic.
Thanks to everyone for all the info.
PVC should be safe... Temps should be low enough by that point. Just be sure
that the pipe slopes downward with no upturns anyplace.
If you can turn 90' (or even 45') and make the run shorter, do that.
(a). any kind of plastic will burn (given sufficient conditions -
the circumstances which create those conditions are highly
unpredictable). why chance it ? use metal ducting.
(b). wouldn't you want hot dryer exhaust gases to flow upwards out
of the duct, vs. down a pipe ?
Metal ducting under concrete means cast iron pipe! Certainly not aluminum
Very many plastics are fireproof. One of the earliest, Bakelite, for
PVC is flame-resistant and self-extinguishing. It will burn only if a flame
is continuously applied and even then very reluctantly.
I have never seen this done before, but one thing I can add is that aluminum
and concrete do not go well together. If you are going to install duct I
would suggest the galvanized steel type. Something which is very solid and
steel is 4" EMT which is available at an electrical supply company. EMT is
approved for concrete encasement. The actual outside diameter is a little
bigger than 4" so you may have a problem connecting to 4" duct. 3.5" EMT
might be just right.
the longer the run the slower the drying and more energy wasted
espically when lint collects.
i would look into moving the dryer or taking the vent UP and vent ont
the new concrete deck.
what your proposing will cause endless grief espically if its a long
run or has any bends.....
I have installed several dryer vents thru concrete with PVC
pipe. Code in this area limits you to < 30' total run and no
more than 180 degrees total in elbows. Less is better,
straight is better, larger is better. No less than 4" pipe
and, if needed, put in a clean out.
Many new homes have washer dryer areas in the middle of the
home for convenience and a pvc pipe through the concrete can
provide the shortests, straightest run to vent.
I have never seen this done, nor seen any specs for using
aluminum in this situation, so I would avoid that for several
reasons, including; strength, deterioration in contact with
cement, and difficulty in maintaining proper slope. Make sure
to have at least 3" of concrete above the pipe (vent). This
may require burying it under the concrete rather than running
it through the concrete.
PVC has a static problem and will hold lint better than metal.
You do not want this.
Pipe bigger than 4" is not better.
The larger diameter pipes will not allow for the velocity of the
clothes dryer blower to get the exhaust of lint and moisture out.
Cetified Dryer Exhaust Technician
As someone else said this is bad and probaly the dumbest Idea ive
heard yet run the vent up higher on the wall but thats not the best,
move the machine as that is the best how cold is your world and think
of ice as you run the machine thru a metal pipe . As a certified
whatever you don,t stop this Alisa then stay away from my machine also
here Pvc is against code as if a fire starts in it it will spread
Metal is all that is allowed now.
Then your code writers are morons. PVC will neither burn nor support
AMENDMENTS TO INTERNATIONAL RESIDENTIAL CODE
B. The International Residential Code adopted by reference in Section101.2,
2000 International Building Code, is hereby amended as follows:
Section G2437 (Clothes Dryer Exhaust) is amended by adding section
G2437.5.3 to read as follows:
G2437.5.3 Under slab installation. Exhaust ducts for domestic clothes
shall be permitted to be constructed of schedule 40 PVC pipe provided that
installation complies with all of the following:
1. The duct shall be installed under a concrete slab poured on grade.
2. The underfloor trench in which the duct is installed shall be
backfilled with sand or gravel.
3. The PVC duct shall extend not greater than one (1) inch above the
concrete floor surface.
4. The joints of the PVC duct shall be solvent cemented.
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