Enlarge 3 inch dryer vent through concrete


Old 07-06-18, 05:31 PM
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Join Date: May 2010
Location: USA
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Enlarge 3 inch dryer vent through concrete

The dryer vent hood on the outside of my house is through concrete. It is only 3 inches wide. I have a 3 inch reducer going from my 4 in duct to it. I would like to enlarge the hole to 4 inches. What would be the best way to diy? Looked into renting a core drill, but it was very expensive. Some companies want 90.00 just to come and look at it for an estimate. House was built in 48 and has cinder block in the basement and brick facing on the outside.
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Old 07-06-18, 05:54 PM
Join Date: Oct 2008
Location: New England
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I was looking for the block reference and you made it. Blocks will be a lot easier than a poured concrete wall. Not a pro on this but remove the current vent hood so you can see where in the block that 3" hole went through. Blocks have dividers and spaces and is your space is wide enough then just removing some of the material to the sides will do. If one of the dividers is in the way then it can be busted out.

Some combination of masonry drills and hammer and chisel will get you to where you want to be.

Pros will be along.

Old 07-06-18, 08:46 PM
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You can get a cheap 4 1/4" core bit for about $50. Cut a hole in a board to use as a guide to get the hole started. Fasten the board with the hole across the ooening, then drill it out. Have someone squirt water with a garden sprayer as you drill.
Old 07-08-18, 04:37 PM
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Join Date: May 2010
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Thanks for the advice. I own a corded dewalt drill and a 19.2v craftsman, both have 3/8 in chucks. In searching around, seems the 4 1/4 core bits are 1/2 in or made for core drills. Do they make a core drill with an adapter for a 3/8 in chuck? I would rather use a core bit but I donít have the right equipment. May just do the drill and chisel method😒
Old 07-08-18, 04:58 PM
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Cinder blocks are a piece of cake, a series of 3/8" holes with a mason drill then bust out.

Bricks can be tougher, process is the same but you dont want to beat on them too much to loosen mortar so many more holes!
Old 07-08-18, 05:37 PM
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Do they make a core drill with an adapter for a 3/8 in chuck?
You need the power of the 1/2" drill to power that bit.
Hammer and chisel........ been doing it for years.

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