Is a thimball needed for a dryer vent

Hello,

Do I need a thimble for venting a dryer? I'd like to move my dryer and assumed that I did not need one, but one of my favorite plumbing books mentions using one.

I can not find anything in the current Illinois plumbing code specifically saying that I need one. It seems like overkill...

Thanks,
Steve

Must be a local thing.....what's a thimble?

Thimble

I had to look this up:

Thimble \Thim"ble\, n. [OE. thimbil, AS. ??mel, fr. ??ma a
thumb. [root]56. See Thumb.]
1. A kind of cap or cover, or sometimes a broad ring, for the
end of the finger, used in sewing to protect the finger
when pushing the needle through the material. It is
usually made of metal, and has upon the outer surface
numerous small pits to catch the head of the needle.

2. (Mech.) Any thimble-shaped appendage or fixure.
Specifically:
(a) A tubular piece, generally a strut, through which a
bolt or pin passes.
(b) A fixed or movable ring, tube, or lining placed in a
hole.
(c) A tubular cone for expanding a flue; -- called
ferrule in England.

3. (Naut.) A ring of thin metal formed with a grooved
circumference so as to fit within an eye-spice, or the
like, and protect it from chafing.

I think she is referring to the sleeve protecting combustibles when going through a wall.

if you let lint go into your vent tube, it collects on the inside surface walls and eventually either rots or burns. When it rots it smells. Dry rot, based on ambient humidity. Gives your house that lived-in smell. A lint fire in a conduit doesn't burn the whole building down.

david

thimble

A thimble would be needed if your dryer were connecting to a 10x3" rectangular duct in the wall. It would provide the 4" round connection necessary for connecting the dryer. But if you use 4" round pipe, then the elbow that comes out of the wall becomes the "thimble".

Thanks for the help!

hj said:

A thimble would be needed if your dryer were connecting to a 10x3" rectangular duct in the wall. It would provide the 4" round connection necessary for connecting the dryer. But if you use 4" round pipe, then the elbow that comes out of the wall becomes the "thimble".

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That makes sense. I was wondering why I would be needing one for 4" round pipe!

Steve

the definition I have always used for a thimble is a device to provide an air space or insulation from combustibles in a heating unit, usually a flu pipe.
write up from a hard ware site,

Adjusts for various wall thicknesses from 4" to 6". Provides proper clearance for vent from combustibles and serves as a firestop. This Ameri Wall Thimble is one of many top quality items in our Misc Stove Pipe Parts department. http://heating-and-cooling.hardware...ove-pipe-parts/ameri-wall-thimble-670296.aspx

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picture below,

the item used to make a go in to a duct or to come off of one is a take off collar, two pictures of take offs,

and transition would be use to change from a square to a round duct,

as to its use or requirement I would check with the manufacture of the unit, as to its need, or suggested use, or local code.

on electric dryers I have never heard of it being used, and have never dealt with gas units. It only been a few years that they have done away with the uses of the flexible plastic hose,