Dryer ducting

The dryer has a duct like this: There is dryer hose at the dryer that connects to 4" duct, which goes vertically down for about, umm 3-4 feet, then a 90, then a run of about 20 feet. I just cleaned the ducts of quite a bit of lint. I'm wondering if something could be put at the 90 ell, such as a box, that would be below the horizontal run where the lint could collect and be taken out rather than collecting in the long horizontal run.
| |-vert duct | | _________________________________________________| |__ _________________________________________________ | <-- box horizontal duct | | |_____\\ -door to collect line
Would this make sense, or would the box interfere with the flow of exhaust? The vertical and horizontal runs are 4" metal duct.
--
charles

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On Mar 5, 10:26 pm, snipped-for-privacy@earthlink.net (Charles Bishop) wrote:

I wouldn't be worried about the box interfering with the flow, (even though it might) I'd be worried that it WOULD allow lint to collect and cause a blockage. Better to get rid of the hose and have a rigid connection between the dryer and the pipes to help flow and remove lint catching turns & twists. Then change the 90deg elbow to two 45deg elbows like a sweep elbow plumbers use to help drains flow better. Finally if possible make the horizontal duct flow downhill if you can.
The fewer hard turns the better.
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I replaced a long electric dryer pipe that was made of aluminum sheet metal. The metal would drain the heat from the hot air allowing moisture to condense on the inside of the pipe which would then collect lint, it required cleaning of the wet lint every 3 months for the dryer to work properly. I replaced it with PVC sewer pipe, the type for underground drainage. The pipes and fittings are smooth inside and the plastic holds the heat in so that I only have to clean it out after several years. One thing I did add were two clean-outs. Using a PVC "tee" and a cleanout fitting, it is easy to unscrew the 4" plug and run a brush through the pipe to clean it out.
Possibly you could use something similar.
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makes sense and PVC is cheap.
Group, any reason not to use PVC?
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I think I would have kept the nice robust metal and wrapped it with some suitable insulation to reduce condensation issues.

Fire risk? It's probably not a huge risk but it may put you in violation of local codes. Check with your local inspectors and see what they have to say. I understand some inspectors will only sign off on PVC vents if they are burried in concrete.
I guess static might be a minor issue too.
--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
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On Mar 6, 1:49 pm, snipped-for-privacy@malch.com (Malcolm Hoar) wrote:

agreed fire might be a concern and is probably against code but wouldn't those cheap flexible rubber(?) ducts be more likely to catch fire than schedule 40?
also most of the dryer hoods have a plastic cap and doors where they exit the building.
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Malcolm Hoar wrote:

PVC either doesn't burn or has a very high resistance to ignition, depending on the breaks.
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The way I see it, fire is a less of a risk than with the thin vinyl dryer tubes they sell for dryers, also gas furnaces and gas water heaters use PVC as an exhaust for the burnt gasses.
I understand that a gas dryer would not be appropriate to use PVC unless it was rated for it. I have used this system for 20 years with no problems, actually so few problems that it is hard to remember to give it a cursury cleanout every few years.
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How cheap is 20 feet of 4 inch PVC piping? Also PVC 4 inch connectors run about $4/ piece. Is it cheaper than 20 feet of galvanized 4 inch? Five foot sections run about $5 here. Also if condensation is a problem, why wouldn't insulation be the cheapest solution? I wouldn't use vinyl tubing at all.
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(Charles Bishop) wrote:

makes sense and PVC is cheap.
Group, any reason not to use PVC?
*I thought metal is required for dryer duct. A call to your building department should clarify this. If you have the same problem as the previous poster you can insulate the duct.
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Future owner decides to tie a new drain into the existing "drain" and then can't figure out why the water comes out the dryer vent.
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Christopher A. Young
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On Mar 6, 3:24 pm, "Stormin Mormon"

2 big reasons not to use PVC.
1. It is against most building codes. 2. The PVC will attract more lint than the metal due to static. I clean dryer vents everyday and PVC causes the lint to "sheet" and harden which blocks the vent once an edge gets loose.
Alisa LeSueur Certified Dryer Exhaust Technician http://CleanYourOwnDryerVent.com
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CDET 14 wrote:

The trick is to prevent lint from entering the exhaust system in the first place - fight the disease, not the symptom.
One way is to have a short run from the dryer into the bottom of a container partially filled with water (an old wet-dry vac will probably work). From above the water line, exhaust the pressurized air.
All the lint is trapped in the water!
You must clean out the crud from the container once every so often, but you can sculpt some really neat looking things with the fiber-mache.
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CDET 14 wrote:

OH MY GOD!! Another trade group!
Dryer Vent Cleaners of America
And they will certify you making you a:
Certified Dryer Exhaust Technician
Hurry! Positions and territories are going fast!
TDD
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The Daring Dufas wrote:

Do they have their own newsgroup?
alt.blow? alt.ventnotrickle? rec.lintbegone?
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Good idea. If PVC can be, and is, used for high efficiency furnace venting, then logically it will work for dryer vents.
Joe
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On Mar 5, 9:26 pm, snipped-for-privacy@earthlink.net (Charles Bishop) wrote:

These are one of the reasons I have never put a dryer anywhere except on an outside wall. And never had any lint problems. Architects these days seem to be pretty uninformed when it comes to designs compatible with our appliances.
Joe
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My dryer is in my basement. It was vented into the crawl space, but I noticed it was molding the floor joists, so I had to reroute the venting. I ran about 20 feet of metal dryer vent hose to the back of my house attached to the above floor joists. I had problems with this almost immediately. Water would condense inside the hose and the hose would sag to the point that it would become blocked by the water and the dryer would no longer vent. So I finally decided to use PVC. I cut two 4 inch holes in a 5 gallon bucket lid, then attached galvanized fittings to the holes. Then I ran some metal dryer vent hose from the dryer to one one the fittings on the bucket. I then ran another metal dryer vent hose from the other fitting on the bucket to the PVC which I have running to the back of the house via the floor joists above. The bucket serves two purposes, the first is it acts as a lint trap and the second is that it catches any water that condenses inside the PVC. Just made sure your PVC is sloped back towards your bucket. Yoyu will have to empty the water from your bucket every one or two months.

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