Is a 20' Dryer Exhaust Run Normal? (3.5" PVC)

Old 04-15-20, 05:03 PM
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Question Is a 20' Dryer Exhaust Run Normal? (3.5" PVC)

Laundry room is in the middle-ish of the house. We frequently have issues getting a load of clothes dry, even after purchasing a new dryer. Sometimes 3 cycles before load is dry.

Weve reconfigured the hose from the dryer to the floor a number of times. Weve attached a leaf blower to the floor port to verity air can get through. Weve checked for blockages on the grille outside.

I found the 3.5 pvc size odd, as well as the long length of run (20). Is this possibly something I should address?

Quick clip.

...maybe I should clean up the wires while I'm at it.
Old 04-15-20, 05:41 PM
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For the most part..... PVC is not approved for dryer venting due to static buildup.
The 3-1/2" isn't helping either.

20' is a little long but sometimes can't be helped. I'd switch to 4" metal duct.
Two 45s instead of a 90 is better too.
Old 04-15-20, 05:52 PM
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I have never seen a dryer vented through PVC. IMO 4" steel duct is the best but I do not know if that will help your dry times.

Check your dryers manual about max duct length. You might need to add a booster fan.
Old 04-16-20, 03:11 AM
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Post a model # of dryer, May have a different issue.
Old 04-16-20, 03:54 AM
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20' is not in excess, when you get up into the 30-40' then your reaching the upper limits,

PVC pipe is not approved for venting a dryer and would be much more restrictive, Id get it replaced!
Old 04-16-20, 05:42 AM
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My inspectors would never allow PVC for a dryer vent. It is a fire hazard. Lint fires in the exhaust duct are not uncommon. A galvanized steel duct can contain the fire long enough to burn itself out while plastics can not.

If your pipe is 3 1/2" diameter on the outside it is likely 3" pipe. A 3" pipe has an area of 7 square inches to carry the dryer exhaust. A 4" pipe has 12 1/2" of area. That extra 1" of pipe diameter almost doubles the area to carry exhaust so it does make a big difference.
Old 04-16-20, 06:16 AM
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Yes change it to 4 inch metal.
Looks like you will be able to change it all the way into the laundry room at that end.
The exhaust end looks like it could be a problem.

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