chimney failure

[ArkansasOven]

Hello. I think I may have a problem with my chimney.
The depth of my oven is 37". I have a 17" x 12" opening and a 6" chimney that is built up with firebrick and a 2 foot pipe, 44" altogether.

With a fire in the oven, I have smoke coming out the front of the oven as well as going up the chimney. I think it may be because my front decorative arch is too high and exposes the smoke shelf???

[dmun]

Re: chimney failure

Try temporarily pulling the chimney cap off and see if it makes a difference.

[Les]

Re: chimney failure

What happens when you are up to temp? The last pic looks like pretty clean.

[ArkansasOven]

Re: chimney failure

pulling the chimney cap off does help, but not greatly. When u are up to temp, it still comes out the front, all those pics were taken at the same time, just different angles and natural lighting.

I think I am going to pull the 6" pipe for an 8" tile 3ft instead of two(reforming the base for the improved flow) and add a lower course to the entry arch. The arch will then be below the smoke shelf and it will more than double the volume of draw.

This sound like a good fix?

[brickie in oz]

Re: chimney failure

The inner lintel is too low in comparison to the outer arch, the smoke is wafting out past the arch before it gets the chance to be drawn up the flue.

The reverse would give you excellent draw.

To fix?
Post some more detailed pics of up the flue/arch to help us see how to help with a remedy.

Edit:
Plus it looks like there is only 100mm or so depth to the flue opening.

[david s]

Re: chimney failure

It may be easier just to lengthen the height of the flue pipe to increase draw.

[brickie in oz]

Re: chimney failure

Here is the front of mine, the inner brickwork is only 40mm above the outer arch and there is minimal smoke out the door.

I dont think a taller flue will help in your case, you can try it, but the issue with your smoke is with the bottom of the flue.

[david s]

Re: chimney failure

Before you jump in and make drastic changes there may be a couple of other things you could try. If your oven is new it will still be moist even after some firings. New ovens are notorious for being smokey and a bitch to keep the fire going properly. Also try the "top down method" for smoke free start up and also try lighting the fire under the flue which will heat the flue and create draw. Once the fire is going ok then you can push it back into the centre of the oven. Overloading the chamber with fuel is another cause of excessive smoke.

[ArkansasOven]

Re: chimney failure

The opening is just a bit over 3x17 inches. The arch looks way to high, so adding a lower course to that isnt a big deal. And the chimney isnt sealed off so going to a larger flue tile instead of the pipe (if I dont use the pipe, I dont pay for it) isnt a big deal either.

Adding a foot to the overall length of the chimney is not something I wanted to do as this thing looks massive already and I am not sure what another foot will do to that look.

Here are the pics.

[ArkansasOven]

Re: chimney failure

As for the newness of the oven??? I had a few fires in it last year, baked a few pies even. Here I am middle summer a year later and having the decorative brick added. Not sure how that rates for new? Not being a smart ass... I just dont know.

[brickie in oz]

Re: chimney failure

In my opinion the 3" is too narrow, its not like a vacuum cleaner that sucks the smoke up so it is restricted there to start with.

Get some sticky tape and tape a cardboard false arch onto the front of the brick arch but lower than your steel lintel, light a fire and see how it goes.

Adding to the height of the flue wont help if it isnt drawing at this stage.

Ive been involved with building chimneys and remedying other ppls builds for a while, this shouldnt be too hard to fix.

[david s]

Re: chimney failure

If you don't want to add height to the flue then going to a larger diam. will increase the power of the draw. This might be a simple option and avoid any structural changes.

[ArkansasOven]

Re: chimney failure

Thank you for all the replies. I got an 8" flue tile and placed it. After doing this I lit a medium sized newspaper fire inside the oven and nothing appeared to come out the front. Knowing two things, its loosely placed. no mortar and no insulation that it will draw better than what I had, especially once it is installed and insulated correctly.
I also chipped out the back 1/3 of the arch to increase the area/flow in that space too. This was very minor and took almost no time and it fixes all the things you all addressed and what I believed.
Great forum, great help. Thank you guys once again. I will post final build photos when this monster is done. (fingers crossed that it will be tomorrow evening, US, Central time...)

[ichsan]

Re: chimney failure

I make my inner arc higher than the other. 26.5cm for inner & 25 cm for the other

If I cut my WFO the inner arc (1) is higher than the other (2)
This is my WFO Opening, may be help for your next WFO

[david s]

Re: chimney failure

Doesn't this make it difficult to fit the door?