Question DVL to snout connection

[stoveliker]

I had an air leak where my DVL connects to the single wall (....) snout. That connection is inside my poured concrete.. (There are no clearance issues; within 2 ft all is stone veneer and concrete.)
I had patched it during the burning season with furnace cement to the point I had zero air going in and made sure that I had no change in CO readings.

Likely when moving the telescoping DVL in order to take it out for checking/sweeping mid season, the jiggling messed with the connection. None of the two "seams" were fixed with screws, it turns out.

The hole in the concrete is far larger than the pipe needs, at least at the place where the pipe comes out into the room.

I am attempting to redo this properly and have a few questions.

1. See the pics. There was this piece connecting the snout to the first DVL section. I didn't pay attention when I took things apart. Which way goes to the single wall snout and which way to the DVL?

2. I am hoping to put some screws in, from the inside to the outside (outside in is not possible because this is inside my poured wall) to fix these parts and stop their movement. Is that okay? (Normally screws go from the outside to the inside.)

3. There is about 2-3" of space between the bottom of my pipe and the concrete where the pipe comes out of the wall. What mortar should I use to build that area up to give more support to the piping? Preferably something I can get at a (orange or blue) box store premixed.

This is not my area of knowledge...

 

[begreen]

The right side image (second) looks more correct to me.

 

[stoveliker]

Okay, thanks.

Any concerns about screwing that right part into the snout from the inside?

 

[begreen]

That should be ok. Another option would be to pop rivet it with stainless steel pop rivets.

 

[stoveliker]

Good point, that's what I'll do.

That leaves the third question above (about what material to use to fill the top large hole in the concrete).
I guess @bholler would know but he's offline at.this time.

Anybody else with more insight than me?

 

[begreen]

How large of a gap needs to be filled?

 

[stoveliker]

The gap is 2.5" larger diameter where the pipe enters the concrete than the OD of the pipe. A bit uneven 2-2.5".

 

[begreen]

That's a good sized gap, too large for some rope gasket. I'm not sure I would mortar directly to the snout. It is bound to move a bit with cleaning and expansion during heating.

 

[stoveliker]

Yes. The hole is conical (?); it is larger at the inside edge of the concrete wall than it is farther in. The snout ends somewhere halfway in the wall. There it's decent (0.5-0.75".gap around the end of the snout).
At the inside surface of the wall it's at least 2".

I'm afraid I'll have to do concrete (i.e. mortar plus gravel), but don't know if it needs to be special because of the temp. The snout is single wall, so is that connector piece in the image above. From that on towards the stove it's double wall.

It appears others have added concrete before at this end but that broke off. Likely because adherence to the concrete of the wall was compromised due to previous leaks; wall concrete is black/brown at the bottom, could be rust or creosote. So I'll be grinding that away to create a fresh surface.
My pipes are fine. I think that leak happened before the chimney got lined.

I would like a suggestion of what (hopefully box store premixed) stuff I could use for this