Mongo's 42" CT Build

[mongota]

Ladies and Gentlemen, boys and girls, children of all ages...

I'm back!

Had a couple of absolutely bizarre issues that came up with out-of-state extended family that 100% pulled me away from any home projects (as well as pulling me away from home) over the last year. The fire brick dome was plastic sheeted and double tarped for the past two winters, since October of '16. Amazing that it was for that long.

About a month ago, I untarped the WFO. Unfortunately, the three layers of protection suffered abrasion during the winter winds and allowed some water intrusion. The 4" of ceramic fiberboard insulation under the dome was absolutely saturated. Press on it and water would weep out. A sad discovery indeed. I even had fungi growing out of the insulation on the exterior! lol The good news is that other than being wet, the board insulation seemed structurally sound. There was no thickness compression from the weight of the brick.

After several weeks of drying, I've made some progress. More posts and progress pics to follow.

It's good to be back on this forum as well as getting the oven back up to speed!

[cnegrelli]

Hope to hear Mongota's updates soon as I wait for freezing temps to subside here in CO before I can start. Cool build. By the way, grew up just up the river in Haddam, where my family has lived since the 1600s and my Mom is from Deep River. Essex is one of the most beautiful spots in the world! Your build is up to the local standards!

[rand18m]

Very neat project, looks like a fun build.

[JRPizza]

The mock-ups will tell you a lot. I had an idea of what I wanted to do, but when I started mocking up I had to change my plans a little to keep my mortar joints from aligning.

[mongota]

I could get away with those four plus a couple of shorties I have in my remnant pile to create the transition, but a concern has been the small footprint of that minimal transition.

I plan on giving the vent arch a good look-see when the rain stops and then I'll do a couple of mock-ups for the chimney transition. I think by creating a cap with a larger footprint on top of the vent arch it'll better distribute the weight that the chimney transition puts on the arch toward the sides of the arch instead of it being more concentrated on the apex of the arch.

I have to say the arch as is is pretty strong. When I buttered up the front and rear keystone bricks with mortar and set them in place, I was "tapping" them pretty good with my 2 lb hammer to squeeze out the excess mortar and to drive them home. I was surprised I didn't break the bond of one of the other mortar joints in the arch.

[JRPizza]

Nice looking arch work! Do you think 4 bricks are all you are going to need? I ended up using more bricks than I thought for my arch to chimney transition.

[mongota]

Here's the pallet of brick I started with...
And the pallet I ended with...

Just enough. I'll use those last four brick on top of the vent arch to create a level surface on which to attach the chimney anchor plate.

[mongota]

Okay, got some uploaded.
Pics of the vent arch and throat.

[mongota]

Pretty heavy rain today so no work on the dome, but I peeled back the tarp to take a few photos.

I left a 1-3/4" reveal around the dome arch.
And a couple of shots of the vent opening.

Meh, can't upload photos. I'll try again later...

[mongota]

Thanks Mike. Just got home from a trip to the west coast, unfortunately...it looks like rain over the next couple of days. Yet ANOTHER slide in the schedule. And so it goes!

[SableSprings]

Great job Mongo! I really like getting that nice curve for the flames/heat to flow smoothly into a collection area and then the flue. Your freehand double round-overs look very nice and will certainly get the job done! Looking forward to seeing the rest of the vent system getting put together...after you get a little rest

[mongota]

(yawn)

Finished the vent arch today. No "done" pics as I was in a rush to pick up my bride at the airport. But a couple of progress photos:

Used the angle grinder to round over the bottom inside corners of the bricks that make up the flue entry. The corner bricks with the double round-over were a little tricky, But I just went at it freehand and they turned out fine.

I can;t do anymore work until this weekend, hopefully then I'll get and flue anchor plate in place and get some blanket insulation in place.

[mongota]

Then on to the vent brick. I cut an "L" in the end of the vent bricks so they wrap around two sides of the dome arch brick, with the two runs of ceramic rope filling the gap between them. I back cut the end of each vent arch brick at a slight angle so only the inside edge of the vent arch brick touches the face of the dome arch brick.

Originally I was going to just reply on compression to seal the rope between the two bricks. But I ended up running a bead of RTV on the two ceramic fiber ropes as I set each brick, that way I won't have to compress the rope as much. With less compression, It'll allow for more independent movement as the hot dome bricks expand and move next to the cooler vent brick.

I cut and dry fit five courses of brick for each side of the vent arch today. I'll mortar them up tomorrow before lunch, let them sit for a few hours while I do other projects, then come back late afternoon and cut the brick for the rest of the vent arch. That's the plan at least. Anyhow, I'm glad I got a couple hours of work in today. Progress is always good.

[mongota]

Work, weather, work, work, kids, procrastination, nappy time, etc. Anyhow...

Three weeks later and I FINALLY started on the vent arch. I thoroughly wasted the last few days not working on this, but other things kept cropping up.

Anyhow...I want to thermally and structurally isolate the vent arch from the fire brick dome. As we all know, the dome can see much higher temps than the vent, and differential expansion could lead to structural issues were they conjoined.

The following is not a perfect way to do it...there will certainly still be some heat conduction from the dome brick to the vent brick. But I'm trying. The vent bricks will not be mortared to the dome bricks. The vent bricks will simply be butted up against the dome bricks, separated by a gap filled with two pieces of ceramic fiber rope.

I bought some RTV high-temp silicon and some 1/2" ceramic fiber rope. I ran a couple of beads of silicon on the dome arch, one on the top of it and one on the face of it. Then I bedded the 1/2" ceramic fiber rope in the silicon.

[thevance53@gmail.com]

Plug looks great. My remaining hole ios a little smaller and I was debating whether I do a larger two piece plug, but after seeing your method, I will try your way. I drew the pattern and started cutting bricks today. Hopefully I can plug the hole tomorrow, Thanks for posting the technique.