Castable Refractory Products (VT600)

[TARibs]

And the 28th was first day actually trying the oven. Ran out of time for putting a Stucco layer on it as you need 45 degrees for 48 hours and by then it was too cold.

IT WORKS!!!! still having issues getting Pizza to cook right but we're getting there.

[TARibs]

Fired up the oven last fall with a number of small fires before trying to cook in it, I know I at least did fires on the 13th 15th 17th and 28th, suspect there were some in between 17th and 28th that I just didnt take pictures of as the 28th was the first attempt at cooking. Looking at the Oven you can see at some point this was when I also added the layers of Vermicrete over the blanket

[TARibs]

Next up was insulation, original plan was for just vermicrete but based on the space I had left on the slab I thought the ceramic blanket with a thinner layer of Vermicrete would be a better alternative. I got 100 foot role and then went to work wrapping, I used a roll of rebar tie wire to hold it in place. I tied it to a few screws that I simply drove into the vermicrete base layer below the Firebrick. Again I had an issue with a leak behind Flue gallery, I'm happy I fired the oven before completely covering it and I would recommend this. I pulled away the fire blanket and repaired this section. Then after replaced put the fire blanket back, finished with the chicken wire and added more vermicrete before testing the oven again. You can see I also used chicken wire over the tie wire, I just thought it would be easier to place the Vermicrete and I believe it was. The chicken wire was not easy, I spent days just bending and trimming the overlappting section, to get it flat, I did a lot of tucking under the seams with small needle nosed pliers and bdending over parts of it to get the overlapping sections how I wanted them (you might be able to see tis in the last photo.

[Fishman]

Thanks for the updates Tom! I am curious how many bags of material did you end up needing for the casting?

[TARibs]

And a few more of the Arch for any interested. I did take a grinder to the flue casting and smooth it down quite a bit.

[TARibs]

The Flue Gallery was an issue as it kept leaking through the original seam joining it to the casting. After replacing it a few times and then getting enough insulation on top of it that seems to have stopped. I do notice some small cracks where it meets the brick so over time if may require digging out and replacing again

[TARibs]

So due to the way I had to place the refractory cement (multiple small blobs) all done continuously you can see the inside result isn't perfect, See all the lines, I was originally concerned and tried smoothing it out with a thin layer of refractory cement, This looked good in a picture but over time it has spalled off, the oven is back to seeing all the lines but as yet has not developed any cracks

[TARibs]

Haven't posted much on progress but wanted to add to my little story. This is the Cast chimney construction, worked pretty well. Wood mold with styrofoam core, poured in refractory with SS needles, took form apart and then ground into a nicer shape. Chimney attachment was put in place with High Temp cement and surrounded by vericrete to make it tighter

[david s]

Yes, you can do that, but remember that a small gap of 1/2” or so won’t do much to prevent heat. It may reduce heat by conduction, but do little to prevent heat travel by radiation. After all you wouldn’t expect 1/2” of insulation over your dome to be very effective. The primary function is to act as an expansion joint and to prevent expansion damage to the outer oven parts. In the case of my oven design the flue gallery is so light it hardly acts as a heat sink and is also insulated. I have an expansion joint between the flue gallery and the outer decorative arch which is in turn connected directly to the outer oven shell. That way the inner dome and gallery are independent and free to expand inside the outer shell and decorative arch

[TARibs]

Thanks Dave, what about some type of break between the Outer flue area and the dome, Any suggestions?

[david s]

Going very well. Building an outer form for the gallery mould will be very difficult and hard to fill from the top. Just get the consistency right and work it over the form. I wouldn’t be bothering to have the brick sides faced with castable. Much easier just to have the cast section sitting on top of the bricks. The casting should be insulated but don’t worry about the brick sides, they don’t get particularly hot.

[TARibs]

Getting ready to build flu gallery, I see some comments that it should be insulated? Is this necessary if wings are going to be brick? Present plan is to cast the upper section (maybe I should insulate that portion?) where the vent pipe will attach and use brick on the lower wings (sides) with a 1 inch layer of Castable inside the bricks. Hope that makes sense, Question is what to do between the transition of the flue gallery and the Oven Dome? Would inserting an inch of blanket there be acceptable? What about an inch of Vermicrete, would that be better? What other thermal break options are there?

I presently have a large pice of Styrofoam to cast over for the flue (see pic) I plan to build an out side form I can place over it in the hopes of applying some vibration and getting a nice smooth surface. Still working on the transition from the Cast to the SS vent pipe. may just put tabs into the cast (grooving the Foam) and inserting the Vent pipe into a slightly larger opening (Seen David suggest this on numerous threads). Thanks

Tom

[TARibs]

So next question the entry way and particularly the vent pipe. I think I know how I'll build the entry but what are options for vent pipes, what works what doesn't? Does clay pipe work, I believe stainless steel is best. Can it be single wall though, the double is pretty pricey. Been looking for transitions between the cast section and vent pipe but haven't seen too much. Any suggestions? Does the black pipe used for a wood stove work? Why not the galvanized (too hot for the pipe I'm guessing)

Thanks

Tom

[TARibs]

So for anyone interested for future builds, what I did was go once around the bottom (about 6 inches high) the 1st day (took 3 hours to get aroundI leaned the bricks against pieces of wood to hold the Castable in place. I knew I would never get it all cast so I cut a groove in the lowest level to get a good key bond ( the next day) with the next level. On the next day I started a lot earlier at 9AM. I gradually went around and around vibrating as best I could ( working the layers together with my hands and a putty knife) to get pieces bonded together. I'm sure the inside is going to have grooves from all the pieces but I believe I got decent bonds between them all. Going over the top was probably the hardest to keep the correct thickness. My son kicked in helping around 5 and we finished up around 10 PM. I was nervous regarding wether I'd ever get the wood out of the interior but once I removed the door (which came off fairly easily) I was able to tap one of the two by 4s and their was enough space in the wood pile to allow movement so I was able to pull one piece out, once it was out the rest followed rather easily. Had a bit of an accident so wasn't able to clean all the sand out but what I can see looks good.

Its all covered and tented today as we're getting a lot of rain and I don't want that. Hopefully start drying air it out tomorrow.

[TARibs]

Finally made serious some progress, I had plenty of wood but not nearly enough sand (plus no place to put it if I bought a lot more) so I started the dome with a nice stack of wood all arranged facing the door so I could get it out. I then covered it with compacted sand and created the front entryway, again not enough sand so I filled it with more wood and bricks. Was very nervous about how exactly I'd "pour" or place the castable without an out form and that part proved to be right. Was very nervous about getting the mix the right consistency so it wouldn't be too soft and just sag, I don't know how the home brew works but the stuff I had was not stiff enough to really stand on it own but maybe I was doing something wrong.