Built a Brickwood Oven, Now what?

[Scope1]

Re: Built a Brickwood Oven, Now what?

Thanks pastor and deejayoh for your comments. Well I am almost done with the original build of my Brickwood Mattone Grande with fiber blanket. I have also closed off about 40% of the face of the oven with firebrick as per their instructions. I REALLY hesitate to tear down the chimney like you pastor....it just looks too pretty the way it is.

I understand the concept of losing the heat up the flue when trying to retain heat while cooking meats ,baking bread and smoking. I don't think that the flue heat loss would be a problem when making pizza especially when the front door is wide open.

I am a simple kind of guy and I like simple solutions. It seems to me that the simplest solution when baking and cooking meats with the door closed, would be to just temporarily unscrew the Dura-Vent chimney cap and cover the opening with 2 firebricks.... that should stop the heat loss. A slightly more complicated solution would be to install a damper under the chimney cap. Does this sound reasonable?

Of course I have never cooked in a wood fired oven yet so I don't know for sure if this would actually work. I'll let you know when I fire it up in about a month.

[pastorryanhayden]

Re: Built a Brickwood Oven, Now what?

Hi,
I've had my oven for well over a year and let me tell you what I did. I filled the chimney, closed off the front at about 63% and then built a chimney in front of the door. The result is ugly as homemade soup, but it works MUCH better than it did before.
If you are still building it, I would highly recommend you ignore the chimney from the kit altogether and plan on building a hood in the front. You'll get much better results. I'll post pictures later when I get some time.

[deejayoh]

Re: Built a Brickwood Oven, Now what?

I am building the same oven (Mattone Barile Grande) , the same way you have done. Why not simply just add firebrick up front to close off the front by 40 percent? That is what I am doing now. All yo need is a few more firebrick and some mortar. Check out their instructions on the oven build sheet. Seems like the cheapest and most obvious solution to me. The front can be closed off at any time.

If I understand your comment, the reason not to do this is because your flue is behind your door. When you close up the oven, all the heat you are trying to retain will just go up the chimney.

The ovens perform better if the flue is outside the oven in front of the 63% height entry arch. They will heat up better and the heat is retained when you close up the entry arch with a door.

Edit: this may help - How a brick oven works (pdf)

[Scope1]

Re: Built a Brickwood Oven, Now what?

I am building the same oven (Mattone Barile Grande) , the same way you have done. Why not simply just add firebrick up front to close off the front by 40 percent? That is what I am doing now. All yo need is a few more firebrick and some mortar. Check out their instructions on the oven build sheet. Seems like the cheapest and most obvious solution to me. The front can be closed off at any time.

[SableSprings]

Re: Built a Brickwood Oven, Now what?

In the above drawing the oven inside height is 17in. The reveal height is 11. 64%.
I'm confused about the flue dimensions though. Could you clarify?

The general answer for flue size of an oven is to plan on a main cross-section flue area 10% of the area of your oven's opening. It is also good practice to include a collection area for the smoke entering into the main flue...acts as a funnel. There is a discussion on flue sizing in the following link (pg 2, post 20 specifically) for the 10% rule of thumb. Be aware, that if you add a chimney cap with a spark arrester you will be reducing the flue area outflow. The 10% is when the flue is unrestricted at the top. If you are going to add an air flow restricting chimney cap, you could get some smoke coming out of the front of the oven even if the flue is sized correctly.

http://www.fornobravo.com/forum/f8/v...help-6344.html

Hope that helps...I also seem to remember there was a spreadsheet calculator for chimney draft available in the forum on one of the older threads. Found it: Here's the thread link...

http://www.fornobravo.com/forum/f28/chimney-flow-rate-calculator-3905.html"

Make sure you go to the last page with the most recent update of the zipped Excel spreadsheet.

[pastorryanhayden]

Re: Built a Brickwood Oven, Now what?

I'm planning on closing the current flue, adding an external arch at 64% and putting the flue on the external arch (the reveal). This is how it looks on most of the pictures I've seen on here. I've already tore down the current chimney and am planning on capping the current flue today.

[pastorryanhayden]

Re: Built a Brickwood Oven, Now what?

In the above drawing the oven inside height is 17in. The reveal height is 11. 64%.
I'm confused about the flue dimensions though. Could you clarify?

[SableSprings]

Re: Built a Brickwood Oven, Now what?

Careful here...my understanding is that the 63% ratio is the height of oven opening to internal oven height--not the flue entry height. Your oven's flue, being at the same height as oven's internal height, means you have a 100% ratio using either the flue or oven opening/entry heights...terms are equivalent in your current oven...if you modify and add an internal arch for the reveal then you need to design the new arch to conform to the ratio range.

For example, if your oven is 40 cm (inside height), you'd want to have your reveal's inside height (the actual opening height) to be just a bit over 25 cm. (That's about 20" inside height to 12.5" opening height.)

That being said, the 60-65% range just gives you the best performance...it doesn't mean it won't work at all (as noted above, the original design is way out of the range and it does still work...just not as well as it "could").

I do think you're going to be happier with the oven going with a "chimney move" and entry rework...

[pastorryanhayden]

Re: Built a Brickwood Oven, Now what?

Something like this? (only centered)

[deejayoh]

Re: Built a Brickwood Oven, Now what?

Flue height should be 60-65% of oven height, both measured on the inside. Doesn't have to be exactly 63%

If you choose this path, I'd use an "axed-arch" design for the entry in order to make sure you leave enough width at the bottom to work. Vertical sides that are slightly wider than your existing arch as to leave a reveal, and then a fairly flat arch across the top.

[pastorryanhayden]

Re: Built a Brickwood Oven, Now what?

I'm seriously contemplating knocking down the chimney, plugging the hole, and putting a flue in a 63% entry arch.
So the 63% entry arch. Is that 63% of height, or 63% of the area of the opening? Does it matter what size flue I use.
I'm sure these questions are answered elsewhere. If you just want to point me to the right thread, I'd appreciate it.

Laurentius,
I used about 3.5inches of perlite mixed with portland cement under the hearth bricks.

[Laurentius]

Re: Built a Brickwood Oven, Now what?

Hi Pastor,

What is the hearth insulation, and what thickness is it? If its the separation between the slab and the bricks, that not enough.

[deejayoh]

Re: Built a Brickwood Oven, Now what?

I would extend the front of the oven as Chip suggests in #4. If you go with # 1 and plug the chimney to bake, I think the oven is going to make a mess smoking out the door when you first put the oven out.

[pastorryanhayden]

Re: Built a Brickwood Oven, Now what?

Brickie,
I could be wrong, but I don't think my hearth bricks go right to the concrete. There are two different types of bricks there, and underneath the hearth bricks there is insulation. The mortared bricks are just a border on top of the concrete.
(You aren't kidding about it being huge though. It took six guys to get it mounted in place and I think we all got hernias.)


Mr Chipster,
Thank you so much for the ideas. What I think I'm going to do is extend the chimney like #1.
I really liked the idea of adding a door inside of the flue, but I looked at my oven and that would make it absolutely tiny in there. So that's not happening.
I'm probably going to add a 63% arch either right inside or right outside of the oven and then build a door with a large flange and add a removable insulated plug insert to the chimney.
Thanks again.

[mrchipster]

Re: Built a Brickwood Oven, Now what?

Here are four ideas.

1- Add two more courses to the top of your chimney, the first course would have the bricks cut to accept an insulated plug. You may need to fabtocare a small lintel support at the front from a piece of steel angle. This could be used in conjunction with the other ideas.

2- Create an insulated plug door with a panel that extends over the flue.

3- build another arch just inside your flue that creates a reveal and lowers the entry to 63% and build a door with a flange that seats on the reveal. This would provide the best fire and heat retention but would reduce the oven floor space.

4- tear off the current chimney, Plug the current flue, build a new flue arch outside the current oven with 63% height and reveal, and a new chimney. This would also require the building of a door.