Idaho 36" Build

[AJH]

I was planning on removing the outer forms and plastic wrapping it with the inner Styrofoam form in place for a week. After the week I'll take out the inner form and wrap the outside with CF blanket and some mesh for a perl/verm Crete layer like gastagg did. Then a tile finish at some point down the road.

I may use a couple fans to help with drying after the damp cure

[david s]

Forms can be removed carefully after a couple of days. It should be damp cured then for a minimum of a week. Following that it needs to be dried thoroughly which will take at least another week. At 3” thick and with no burnout fibres be very careful heating it up with fire.

[AJH]

Formed the front vent area to the chimney this weekend and poured the 3:1:1:1 homebrew into the form on Sunday afternoon. No burnout fibers, but it's poured 3 inches thick in most places only 2 inch thick on the front arch. How long should I wait to take off the outer form and wrap it in plastic to cure? Also, is there any special drying fire schedule to follow to dry out the new vent area transition? I would like to fire it up this weekend if at all possible.

[david s]

I use a fibreglass mould to cast the flue galleries for the ovens I make. But I think you may be referring to the gallery I made for the repair job on an oven that I documented. The mould for it was made using plaster of Paris and perlite. From memory it was about 7:1 mix. The plaster was used so it would set up really fast and the lean mix enabled me to sand it relatively smooth quite quickly, easy to chip away too. I’m pretty sure I coated it in thin oil to assist that removal..

[AJH]

This could be what you are seeking.
10

David, what is the mix you used to make a mold for the vent area? Also, do you just chip it out after the casting sets up?

[AJH]

This could be what you are seeking.
10

Yeah, that's it! So it looked like it's a couple inches thick with mesh

[david s]

This could be what you are seeking.
10

[AJH]

I'm going to bite the bullet and tear down the brick chimney to open it up more and give myself room to insulate it.

What's the proper thickness of homebrew for a cast chimney transition? I remember seeing a post a while back from david s on the best way to do it but cant find it anymore... Do I need to put in some wire mesh to keep it from crumbling? Should I wait a week before firing the oven back up for it to cure?

Planning on pouring a 10 inch tall transition to the stainless steel chimney, wrapping it in CF blanket, then some perl/verm-crete over that, then tile of some sort. It will add some thickness, but should cut down on the 250 degree bricks radiating heat into my face.

[mongota]

Pizza peels, my wife surprised me towards the end of my build, she ordered online and picked up a couple wooden ones and a couple aluminum ones from Webstaurant dot com. I use the wooden peels for building the pizzas and loading them in the oven, and the metal ones for moving the pizzas around in the oven and removing them when cooking is complete.

The wood peels have a ~14" square paddle (might be 14" wide by 16" deep where it transitions to the handle) with a 24" handle. I like them a lot and would get the same ones if these disappeared.

The metal ones are ~12" square with a 36" long handle. I like those as well. The metal ones she bought are not perforated. When building the oven and thinking ahead I thought I might want a perforated peel, but the non-perforated does the job. Easy to clean, too.

[mongota]

Also, the bricks leading up to the chimney pipe were over 200 degrees on the outside, radiating heat into my face.

As much as it pains me to do it, I'm thinking that I'm going to have to take out the brickwork chimney and make the opening bigger...I'm thinking that I'll tear it down, make the chimney vent opening like 15 inches wide by 8 or 9 inches deep, and then pour a cast chimney instead of reworking the bricks. Then I can insulate it with some blanket and perl-crete so that it doesn't radiate heat into my face.

Does your ovens let that much heat pass by the chimney? Should I just live with it? I don't want to do all the work to still have it blast me with heat and lose the pretty brickwork chimney...

A more graduated flue opening with the larges square inch opening at the bottom and your flue pipe cross section being the smallest could help if you're having exhaust gas flow issues. It's logical to me that it would. But I'll let others with more experience chime in on that.

But flow might not be the problem, it may simply be that single thickness of chimney brick between the hot exhaust gasses and your face. Before demoing anything I'd even consider sliding a thick piece of rigid CF board insulation into the flue on the other side of those chimney bricks. Cut it slightly oversized and friction fit it in place. Shoot some temps on your next fire, then install it, shoot another set of temps, see if it changes things at all. Obviously that depends on your geometries and where the flue pipe lands.

Something like the photo below.

I'd hate to see you demo that work, it looks nice.

FYI, I can stand in front of my oven opening no problems. I can put my hand in the landing, it's warm/hot but bearable. If I put my hand past the dome opening, the delightful odor of burned arm hair is instantaneously released into the air.

[mongota]

The last couple days of drying fires have been more difficult to maintain the temperature.

Once you get the dome insulated it'll retain heat better.

[JRPizza]

If there isn't any smoke coming out the front of the oven I would think the chimney/vent size is fine. If it is venting properly, you are getting hit with radiant heat, which is proportional to the square of the distance between the oven and your body. Adding enough distance to your vent area to significantly lower the heat would likely make the oven hard to work with. Remember you are standing a few feet from an 800F heat source.
That is indeed a good looking chimney and it would be a shame to have to tear it down for a minimal gain.

[AJH]

Got the first round of pizzas cooked in the oven! It took a lot longer to heat up than I originally planned for, but it was probably because I would put some wood in and go putter around until it was down to embers then toss in a couple pieces of wood and forget about it for a while again... Pizza turned out ok. Floor was at about 700-750, dome was 850-ish. Dough was not ready and didn't stretch very well, first pizza got a little over done on the bottom. At the end of the night, I blocked up the doorway with some bricks to see how well it would hold heat. At the 36 hour mark it was at 350. With an insulating door, it should hold heat like a champ.

A couple problems that I'm seeing is on the chimney vent area. The opening above the door arch is about 10 inches wide by 4 inches deep. I tapered it to 7x7 over about a 12 inch rise before transitioning to the chimney pipe. The problem is how much heat is hitting me in the chest. I took a thermometer reading of my shirt after standing a couple feet away and my shirt was 200 degrees! Also, the bricks leading up to the chimney pipe were over 200 degrees on the outside, radiating heat into my face.

As much as it pains me to do it, I'm thinking that I'm going to have to take out the brickwork chimney and make the opening bigger to hopefully draw more heat up the chimney. I'm thinking that I'll tear it down, make the chimney vent opening like 15 inches wide by 8 or 9 inches deep, and then pour a cast chimney instead of reworking the bricks. Then I can insulate it with some blanket and perl-crete so that it doesn't radiate heat into my face.

Does your ovens let that much heat pass by the chimney? Should I just live with it? I don't want to do all the work to still have it blast me with heat and lose the pretty brickwork chimney...

[AJH]

The last couple days of drying fires have been more difficult to maintain the temperature. I usually end up going 100-150 over with an active fire in the oven, but by the time it is down to embers I'm back within the range for the day and it holds for an hour or so before I have to light another fire. This morning I managed to clear half the dome by accident when I was supposed to be in the 600's for the day. With me holding the oven at temp for 12ish hours per day at each 100 degree step, I think most of the moisture has been driven out by now.

One thing that I did not account for is the bricks on the front of the vent area getting so hot. With a semi decent fire going, the bricks about a foot from my face were 175... I may need to wrap my brick work up with some insulation and tile to keep my face from getting heat-tanned while making pizza's...

[UtahBeehiver]

Wet ovens are typically smoky while the water is being driven off. When you get the start using a full load of wood with lots of coals, pull them out over the grease spot and it self cleans the brick.