36" Tall Man's Oven Build

[KINGRIUS]

Re: 36" Tall Man's Oven Build

I'm there!!!

I closed up the dome today!

You're going to have a mile-wide grin on your face when you put that keystone in the top and it's officially closed-up.

You were right Ken. In fact It's been 6 hours since I tapped in the last keystone and I'm still grinning!

Here's a keystone for a keyhole-
I'm going to wait a couple days before I remove the forms, but I'll start the chimney transition tomorrow.

Darius

[vintagemx0]

Re: 36" Tall Man's Oven Build

Dude, that's awesome. I feel your joy!

You don't have to wait to remove the forms, unless you fear it will result in pushing upward on the bricks that are starting to set. Theoretically, the structure is supporting itself now. The last outer archway I made, I removed the forms immediately after I tapped-in the keystone. Just makes cleaning the fresh mortar off the bricks much easier.

So, relax tonight, plot your next moves, and have a well deserved drink of your choice!

Good work!

Ken

[ThisOldGarageNJ]

Re: 36" Tall Man's Oven Build

Hey Darius,
Congratulations..... A job well done, Its a Milestone as well as a keystone

Many Happy Pizza's,
Mark

[KINGRIUS]

Re: 36" Tall Man's Oven Build

Thanks for sharing the moment with me guys! I'll go ahead and remove the forms tomorrow then. Thanks for the tip Ken. With my long arms I might be able to do the last inside patch work from the outside without having to stick my upper body inside, especially since the dome is so low.

I'm not too worried about building my chimney transition out of brick, the only thing I'm unsure about is how to attach the chimney to the top of the brick. If it's in the fb manual, then I couldn't find it. How did you guys attach your chimney?
Oh BTW, it's vodka and tonic!

Thanks,
Darius

[vintagemx0]

Re: 36" Tall Man's Oven Build

It depends on what kind of chimney you're going to use. We used 3 feet of 6" Simpson Duratech (UL 103HT). We used an anchor plate by Simpson that is made for this type of chimney. We drilled holes into our brick and tapped-in lead anchors (dollies) and just screwed the anchor plate down. The chimney pipe just sort of screws on to the anchor plate (twist-lock). Just that simple.

I'm partial to bourbon, but vodka and tonic is good too! ching-ching!

'Morgans

[ThisOldGarageNJ]

Re: 36" Tall Man's Oven Build

hey morgans,
I used fire brick for my chimney because I had enough left for it, I mortared it directly to the arch using heatstop 50 ... works well once it gets going, Only mistake I made was not making the chimney hole big enough in the arch.. I did go two ros of brick higher than what you see in the pic.

cheers
Mark

[KINGRIUS]

Re: 36" Tall Man's Oven Build

Mark, how big is your chimney opening in the arch?

[ThisOldGarageNJ]

Re: 36" Tall Man's Oven Build

Hey King,
Its about 3 1/2 wide x 9 long.. once the fire gets going its fine... i was thinking of cutting it larger with the diamond blade, i could probably get another inch on each side giving me 5 1/2 but i dont want to shut the oven down if i have a problem and have to rebuild the arch and chimney... I think the black on the front of the oven adds charm

Mark

[KINGRIUS]

Re: 36" Tall Man's Oven Build

Mine is 5" deep by 7 1/2" wide. Sounds like I may get a little smoke out the front too. However, my chimney is going to be really tall, so maybe it'll act as a vaccum and suck the smoke right out. Either way, I'm not going to worry too much about it. Thanks Mark!

Darius

[dmun]

Re: 36" Tall Man's Oven Build

my chimney is going to be really tall, so maybe it'll act as a vaccum and suck the smoke right out.

Tall chimneys rule! They can suck a whiff of smoke right out from in front of an oven. They can create a draft to burn wood that's too damp to burn. In theory they can get the smoke up beyond where it will choke out neighbors. I recommend building the tallest chimney you can manage.

[Pdiff]

Re: 36" Tall Man's Oven Build

Stack flow can be sensitive to ambient air temps. If the stack is cold, it will resist hot air trying to rise within it. The old fireplace flue trick of blowing out the stack with hot air might help. As you light the oven fire, you could try sticking a newspaper "torch" directly under the stack to initiate and facilitate the flow. This may be even more true with a tall stack.

[KINGRIUS]

Re: 36" Tall Man's Oven Build

I may end up with an eighty four inch chimney. That would put me 36" above the top of my planned roof. I've heard 36" above the highest point of the roof is the minimum desired clearance to make sure there's no interference with the draft pull.
Thanks for the tip on heating the chimney to create pull pdiff, I'm going to remember that one.

Darius

[ThisOldGarageNJ]

Re: 36" Tall Man's Oven Build

maybe i will throw a couple more courses of brick on top of mine before I try anything else and see how that works ?

[vintagemx0]

Re: 36" Tall Man's Oven Build

Natural draft is a fickle thing. The general rule is that taller is better, but there can potentially be a point where you are too high. As the flue gasses cool, they become more dense and thusly less bouyant which means that this "heavier mass" offers some resistance to flow. However, in the relativley low stack heights we are talking about and the relatively high flue temps we are talking about, this is a bit of a mute point. Pdiff's advice on pre-heating the stack when lighting the fire is excellant and will work every time to establish an intitial draft fast.

I think the over-riding consideration here is an ample throat area servicing the chimney and the effects of wind against the door opening and chimney cap. If you were to measure the draft in the chimney, it would be in the magnitude of 0.8 - 1.1 inches of water column. Very slight in comparison to the outside pressure pulsations that will be imposed by natural wind.

blah, blah, blah... I think that the throat opening serving the chimney and a chimney height designed to carry smoke up-and-away from the immediate surroundings high enough to not be a major nusiance are the main considerations with a WFO.

In our experience with our WFO, we see some spillage out of the door during intense burning. This is accompanied by a dark carbon-laiden flue gas which suggests a very low air-to-fuel ratio. The design of the dome and door opening have a lot to do with effective a/f ratio capability of these ovens. If combustion is not optimal, carbon will be present regardless of chimney design, and it does not take very much spillage out of the door to stain the front of the oven. Having said that, I think the subtle pressure differentials that wind makes on the inlet and outlet of the chimney are the primary reasons for spiilage through the doorway.

My $0.02

Ken Morgan

[ThisOldGarageNJ]

Re: 36" Tall Man's Oven Build

Ken,,,
are you basically saying Im not getting enough air in ? I am at 63% door to dome height ratio??? Once its hot it burn and draafts well,, Or are you saying at start up I am not getting enough air in ??

Appreciate the input

Mark