How would you penetrate a 4" thick block wall to vent a Harman P43?

[SciGuy]

I've torn down the monster chimney that vented our Harman P-43 for the past 5 years to about the 6' level and will cap what remains to preserve the beautiful field stone fireplace on the interior of the cabin . I intend to poke a hole out the back of the fireplace through the 4" thick concrete to run the vent pipe through to a clean out T then up 3' or so to an appropriate termination. I intend to clad what's left of the exterior chimney with an inch or two of polyisocyanurate and cover that with board and batten to match the cabin.

I'm wondering about the best way to configure the area where I penetrate the rear of the firebox. Is a thimble warranted through the non-combustable brick and block? Obviously I don't want a gap that allows drafts in or out.

Thoughts?

Thanks for any informed replies.


Hugh

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[johneh]

Core Drill

 

[SciGuy]

Core Drill

Thanks - Slightly bigger than the outer diameter of the vent pipe then silicone?

 

[johneh]

Most use a thimble but pipe size and silicone would work through
block.

 

[SciGuy]

Most use a thimble but pipe size and silicone would work through
block.

Thanks! It seemed to me that thimble would be an extra expense and overkill in this fireproof situation.

 

[johneh]

Yes, it has a lot to do with fit and finish. If it
can't be seen then you don't need it

 

[EbS-P]

I’ve seen some nice holes done with a 1/2” hammer drill and a chisel. I’m not sure mine would look as nice. But if I didn’t have access to a code drill that’s what I would do.

 

[SciGuy]

I’ve seen some nice holes done with a 1/2” hammer drill and a chisel. I’m not sure mine would look as nice. But if I didn’t have access to a code drill that’s what I would do.

That was my initial inclination and may still be the way I end up going.. Harbor Freight sells some pretty inexpensive core drills that folks seem to have good luck drilling brick with. I suspect concrete block might be tougher but don't really know. Thanks for your experience derived thoughts.

Hugh

 

[gthomas785]

Make sure you keep the foam well away from the pipe

 

[SciGuy]

Make sure you keep the foam well away from the pipe

Yes, I intend keep that and the hemlock board and batten well away from the pipe!