How to minimize smoke on Facade

[tdibratt]

I just started the build of my new oven. Poured the concrete pad this past weekend. Starting to think ahead a bit and have a question regarding the vent area and smoke stack. My last oven show a lot of smoke buildup on the facade. I built it with a angle iron over the entry firebricks providing a lintel. The outer facade is arched and the peak of the arch is higher than the dome entrance lintel. I am wondering if this is why I get smoke that dodes not go up the chimney and exits the front of the oven onto the facade.

Any suggestions?

Thx, Tony.

[christo]

Re: How to minimize smoke on Facade

Things I did to try to eliminate it on my oven:

cut corners on the bricks between the dome and the entryway - this makes it easier for the smoke to roll around and up vs continue to travel in the horizontal directions. I also rounded the corners on the bricks that transistioned into my chimney tiles - every where I wanted smoke to route had a transistion cut on it.

I put in a reasonably long and large diameter flue tile - 8x16 to 8x8 transistion plus 3 ft of 8x8 tile. There is a calculator on the site that lets you see how much flow you are likely to encourage - still gathering data but it looks like we have some reasonable guidelines.

I also made my decorative exterior arch about an inch lower than the arch that comprises the vent. With the vent and the rounded transisitons I still had a bit of smoke on the arch - When I put my decorative arch I made it lower so I could install oven lights in the arch and conceal them and the wires. Turns out that was the final thing I needed to stop the smoke.

Good luck

Christo

[dmun]

Re: How to minimize smoke on Facade

A taller chimney almost always means better draw. How tall was the chimney on your smoke stained oven?

[tdibratt]

Re: How to minimize smoke on Facade

I'd say about 3 1/2 feet tall. I think it was 8 inch flue.

[tdibratt]

Re: How to minimize smoke on Facade

Here's the whole oven photo. Actually is mor elike 4 ft to the top of the clay flue pipe.

Thx

[christo]

Re: How to minimize smoke on Facade

8x8 tile and over 4 feet of flue - that thing oughta draw well.

Does it smoke out the front with a moderate fire or just big ones?

Christo

[tdibratt]

Re: How to minimize smoke on Facade

I'd say any fire. Probably within the first 20-30 mins when the smoke is the heaviest on initial firing.

Thx

[karl]

Re: How to minimize smoke on Facade

Hi,

From the photo it looks like the flue void is very narrow (and short). For the smoke to "roll out" there need to be a certain volume around the entrance to the flue channel.

karl

[tdibratt]

Re: How to minimize smoke on Facade

What do you mean by "From the photo it looks like the flue void is very narrow (and short). For the smoke to "roll out" there need to be a certain volume around the entrance to the flue channel."?

Thx

[brokencookie]

Re: How to minimize smoke on Facade

I think what Karl means is that the transition between the outside and the oven appears to be a little short. It looks like the distance from the oven opening to the outside of the flue is only about 8 to 10 inches. Check out the other ovens on the forum and I think the transitions are between 15 and 20 inches.
There might also be an issue with the ratio of the opening size to the oven size. How big is the chamber in your oven and what are the dimensions of your opening ?
Bruce

[tdibratt]

Re: How to minimize smoke on Facade

Oven is 36 inches. Dome height 18-19 inches. Door is 12 x 19 .


You're right about the distance from the entry door to the outside facade is probably about 10".

[karl]

Re: How to minimize smoke on Facade

If you make a screen to shield off the top of your outer arch (entrance), which you can put in (like a kind of "door") during firing up it will probably force the smoke out the chimney.

karl

[dmun]

Re: How to minimize smoke on Facade

Yes, I agree with Karl. Before you start modifying your entry, make up a draft door to tilt from oven opening to flue back. This will get you more air in the fire and channel smoke up the chimney.

Here's Jim's excellent draft door. note the air inlet at the bottom, and the tilt forward to the front of the flue:



You have quite a tall chimney. You shouldn't be having these problems unless there is an actual chimney obstruction. No dead critters up there?

[tdibratt]

Re: How to minimize smoke on Facade

No critters.

The only thing I can think of is the comment made re the depth of the vent landing. I have the flue sitting on 2 half bricks at either end of the landing so the opening into the flue is smaller than the flue itself.

As I am starting to build another here at my home I want to make sure I make this one better. I have seen many designs out there and find that I am never quite sure how to do that landing part until the time comes and I look to see what fits and perhaps this time I should do some planning ahead.

So if the vent landing should be 15-20 inches, I should set the oven opening back say 20 inches and if you count for the facade which let's say is a brick, then you probably need to set it back 24 inches or so. Is this correct? I did not see specific dimensions set forth in the online instructions. Or is the entire landing from the entry bricks to the facade 20 inches" Seems wide. If you had a 4 inch brick on the facade, your opening would be 16 inches wide from the back of the facade to the entry bricks.

Thx

[brokencookie]

Re: How to minimize smoke on Facade

I pulled that 15-20 inch number out of my head. I don't think I have seen a recommended lenght for the landing but if you look at the construction photos it looks like most builders are using 1 2/3 bricks ( about 15 inches assuming "standard" firebrick) and then a 2 to 4 inch decrative arch. I found the discussion I had seen before here.

http://www.fornobravo.com/forum/f8/s...size-2711.html

This builder built a 50 inch monster. He fixed the smoke problem by extending the landing. It's a nice looking fix and seemed to have solved the problem. You should check out the photos and consider a fix like this if you do not want to build a new oven.

Bruce