K79 Oven Build

[david s]

Re: K79 Oven Build

Soldiers again! Do a search on using soldiers for the first course. Structurally unsound IMO.

[Tscarborough]

Re: K79 Oven Build

The adapter plate for metal pipe is 12x12, and requires an 8x8 opening to work.

[K79]

Re: K79 Oven Build

It has begun!

[K79]

Re: K79 Oven Build

A Few questions here guys: Ok, here is my plan for my arch. It's about 75% complete. I think the other 25% needs to be figured out on the fly. What do you guys think? In the front view I only show a set of green bricks on the left but they are on the right as well. Those represent the arch. Same with the green line. I'm planning on putting a 1" reveal around the inner arch for my door. Sounds like enough to me, but from experience is it? Are the bricks spanning the vent arch in the front and back with the dimensions of 2 1/2" to small to be structurally sound?


And for my enclosure the FB plans show 4" of space for vermiculite around the oven. I wasn't sure if there was some sort of code why they have the roof 4" over the top of the oven and FB blanket. Here are two options. I'ld really like to build the first one so it's not so tall, or do I need to clearance in design two?

Design One:



Design Two:



And Last, is just over a half inch mortar joint on the outside of my oven just for my soldier's ok? I'm worried if I taper them then they won't fit nice and tight on the inside.

[K79]

Re: K79 Oven Build

So is it even possible to achieve an 8"x12" rectangular vent in your arch? Using an 8"x12" clay flue I would think you would want the exact dimensions for the arch vent which would equal an 8" round steel chimney. I'm also wondering how you would work the flashing around the chimney that comes out right at the peak. I've called supervent about their ss 8" chimney (thought about doing this) and they don't even sell any type of flashing for a chimney that comes out the peak.

[K79]

Re: K79 Oven Build

K79 -
here is a sketchup of how I built my arch. Freestanding, and the "L" bricks are in the front. The Gray area is where the vent arch overlaps the inner arch. You'll see there is about a quarter inch difference.

Glad I saved...

[ATTACH]34233[/ATTACH]

When I click on this it says invalid attachment

[deejayoh]

Re: K79 Oven Build

K79 -
here is a sketchup of how I built my arch. Freestanding, and the "L" bricks are in the front. The Gray area is where the vent arch overlaps the inner arch. You'll see there is about a quarter inch difference.

Glad I saved...

[UtahBeehiver]

Re: K79 Oven Build

DJ is kind of right, about heavy duty which I used in my build, they are not only a b*tch to cut they are a #@$% b*tch to cut

[K79]

Re: K79 Oven Build

Do you follow the same principles as your dome when it comes to mortar thickness and your vent arches? Smallest joint possible or do you want a 3/8" joint here?

[deejayoh]

Re: K79 Oven Build

Low or medium duty will both work well. People have also used high duty but I understand its a b*tch to cut and also takes a bit more work to get up to temp.

[K79]

Re: K79 Oven Build

Oh man, why did I read that some people used low duty firebrick for their oven. I'm supposed to be using MEDIUM duty firebrick for my oven right....ahhhh Also the exact dimensions of my medium duty firebrick are 9"x4 7/16"x2 5/16". Dimensions ok?

[deejayoh]

Re: K79 Oven Build

so your entire vent area is sort of "free standing" from the rest of your oven right? Everything from your inner arch out is not attached by touching bricks or mortar.

It was when I built it

Check this post, you can see that I buttressed it with cement blocks mortared to the base. Used an IFB between the vent arch and the cement block to prevent heat loss. I didn't trust it to just sit on the insulation. It rocked a little bit, so I buttressed. Probably a good idea with the arch anyway, since the sides aren't locked to anything.

http://www.fornobravo.com/forum/6/st...tml#post132930

Others have taken different approaches to the heat break. Not everyone has the overlap, some are just built freestanding next to the inner arch. You'll find that after finishing a dome, it's not too hard to build it this way.

[K79]

Re: K79 Oven Build

so your entire vent area is sort of "free standing" from the rest of your oven right? Everything from your inner arch out is not attached by touching bricks or mortar.

[deejayoh]

Re: K79 Oven Build

I'll try

First off, a heat break is an air gap between your inner and vent arches. The theory is that the gap will decrease the amount of heat that leeches from your dome into the arch/landing. Since the arch/landing is an large exposed mass of brick (i.e. there is no insulation on the inner surfaces) it makes quite a bit of sense. It's kind of caught on with builders in the last year or two, it seems. Most professional ovens have them, and lots of folks here have been incorporating them in their builds. I don't think they were generally discussed when Ken built his oven.

So the gap you seen in the "L" in my previous post is my air gap. It goes all the way around the arch. The "reveal" (the lip) is the space covered up by the plywood form in that picture.

You can see the reveal in this pic I just took (all sooty and all!). It's 1.5" all the way around

Here it is with the door in place


I stuffed the reveal w refractory rope and caulk when I was done in order keep the smoke where I wanted it. Thus far, no issues - and the surface of my arch is always quite a bit cooler than the bricks right next to it.

As for mistertoy's vent - hard for me to tell in that pic. It does look like he built the arch with support on either side of the vent - whereas Ken used the inner arch as the back side of his vent. When you do that, you have a single plane of failure for that mortar joint. It's just one big long mortar joint, no staggered bricks. If it starts to crack, it will run all the way along that plane and your arch is now separated from your dome. Does that make sense?

[K79]

Re: K79 Oven Build

Ok, can you explain the heat break you're talking about? That's confusing me. You must have a pretty decent lip around your inner arch for your door to seal to. Any way to take a photo of your vent so I can see what you did with the arch. That photo gives a great idea of what you're talking about but what do you do for the vent?

This is a photo of MisterToy's vent. What's the difference structurally at the vent than Ken's?