48" Mobile Oven Build

[nuovopizzas]

Hey everyone. We’re 1 week and a day out from my intial cast. No cracks formed except for hairline around the joint. Success! I took off the front form for the gallery and I did find some mistakes that I could have prevented if I was more careful. I had my Buddy measuring where it was thick enough and I think he missed a spot. Anyways I don’t think it’s detrimental to the structure and I can put a facade on to cover it.

[nuovopizzas]

Today, 2 weeks post cast, I removed some of the form to get a peek at the inside. The fiberglass is slightly transparent so I can see that the interior of the dome, and it is void and crack free, thank goodness.

I think David's suggested 3:1:1:0.5 blend was a very good one, with stainless steel and AR reinforcement. You can tell that its very binding, especially on little bits that come off. When there's a stainless steel needle going into it, it provides so much strength to the cement.

There are a few mistakes here and there that if I were to do it again I'd fix, like making sure I don't miss adding thickness in certain places. Also having a better form for the gallery. I admittedly botched this one together, but it did the job.

However, I have a bit of a problem that I definitely need help solving. With my form, I made a mistake on the gallery, instead of doing a hole for the flue that contains a recess that I can sit the vermiculite on to create a compressive layer for expansion and contraction of the flue, I just made a 9 inch hole. Worst comes to worst, I can probably put a form in there and stuff some mortar into it. and stick my flue in using david's method of installing flues. Please let me know any other suggestions or concerns that you may observe. Thanks.

[david s]

For a mobile oven you definitely need to have a removable flue. You don't want the thing flapping around in transit. I've done at least half a dozen of these and developed a simple method by making a sleeve into which the flue pipe can slide. I'll let the pics tell the story. You may develop a better or simpler solution so post what you come up with to assist others.

[david s]

Finished removable flue.

I forgot to add I also make 3 little tags at the bottom of the sleeve to prevent the pipe sliding too far down.

[nuovopizzas]

Thanks for the pictures David.

For my health codes, I need to use a double walled chimney. Will I still be able to use your method. This also means that the outer diameter of the flue is 8" while the inner diameter is only 5". Do you foresee any problems with this flue size being too small?

[david s]

A 5” inner pipe is inadequate for a 48” inner diameter oven. You need an 8” pipe. My understanding was that a double flue was only required if penetrating a roof space, but you’ll have to follow the rules provided by your local authority.

[nuovopizzas]

You are most likely correct. The flue will penetrate a roof space, as this is going in an enclosed trailer and the flue will go out the top of the trailer. Any advice here would be greatly appreciate

I see that you can buy 8 inch inner, and 10 inch outer diameter double walled pipes, that is probably the one I will go for, but I now run into the problem that my hole is only 9 inches large, i may need to use a conversion piece or something like that, will need to put a lot of thought into it to see how this can be executed.

[david s]

Ok, I didn’t realise your mobile will be enclosed. You can use the roof to support the pipe so it can be fixed permanently. No need for a removable flue pipe.

[nuovopizzas]

Ok, I didn’t realise your mobile will be enclosed. You can use the roof to support the pipe so it can be fixed permanently. No need for a removable flue pipe.

That's what I figured, I'm still somewhat perplexed by the situation but I'm sure ill work out a solution lol. Do you think there is any problem with using your tab method with a double walled flue. Will the lining come out if I make tabs out of the outer layer of metal?

[david s]

I’ve done it many times using a double flue. I usually stuff some blanket between the two pipes both at the top and at the bottom.

[nuovopizzas]

I just had my stand fabricated. I am now going to pretty much install my ceramic fiber board and fire bricks, and then use 10:1 perlicrete to lock it all in against the metal band. What are the different functions of 10:1 vs 5:1. I feel like I'd want to use 10:1 because I want a really high insulation value to prevent and heat from escaping out the edges of the firebricks into the highly conductive metal. Let me know.

One of my big challenges right now is finding a way to lift the very heavy one piece dome off its mold. I have the idea of sliding some straps beneath it and using a forklift to lift it up, but Im concerned about applying forces that might crack it. Only other option is to get 5-6 guys out there and lift it, but it's so heavy that Im worried someone might get hurt. Anyways, I'll continue to upload pics of my progress.

[UtahBeehiver]

See attached pic.

[david s]

I don’t know the weight that the stand will be required to support, but a 48” oven will be heavy. Without a closer inspection and from a small pic, it is more difficult to judge, but if it were mine I’d be adding some diagonals,Remember that there will be additional stress because of the shifting load in transit from accelerating, braking, cornering and road vibrations. Diagonals add little extra weight while contributing enormously to increased strength.

[nuovopizzas]

Will talk to my welder about adding some diagonals thanks for the suggestion David.

so I recently purchased my duratech 8" double walled flue and chimney cap and I need some ideas on how I can get this installed properly. Will I need to use a anchor plate? I’m beginning to think I won’t be able to do Davids method of cutting it and creating flaps because there’s insulation in it and it seems like I might damage the flue? But maybe not. I am very open to suggestions to getting this installed properly. I also can’t permanently install it until it’s in the trailer because it is going to penetrate the roof. I feel like I’m in some uncharted waters.

[Giovanni Rossi]

Your''re probably going to need a finishing collar with adapter (8DT-FC). This transitions the bottom of your double wall to a single wall.
I think there's enough length on the bottom of that piece that could be modified to do what David suggests.

If you need more length to work with, you could also add a stainless adapter (8DBK-ADSS) or any 8" pipe of your choosing to the bottom of the finishing collar.