Can you have a flue that's too big?

[md_massimino]

I'm planning a 42" high vault dome (thanks dmun for talking me out of the barrel vault). I'm doing this baby on a shoestring, it's the only way I can sneak it through the wife approval system. I'm slowly collecting materials from contractor friends and craigslist so I have a bit of a hodge-podge of stuff right now. Best score so far is 2000 really old, never mortared bricks for $100.

I was gifted a piece of industrial strength flue, about 11" square and two feet long. I'm planning on having a standard oven opening according to the Pompeii oven plans, 20" wide by 12.5" high. Most examples of the vent opening I've seen are about one brick width, maybe two. I'm wondering if I can make the vent bigger so I can use this flue, maybe about one full brick length long, around 8" x 11". Will having a bigger vent and flue screw up the draw? Would love to hear some opinions from the masters, thanks.

[dmun]

Re: Can you have a flue that's too big?

Flue tile is really cheap, and there's no real reason not to use the size you want. Most of us who build masonry chimneys use the 8 by 8 flue tile, it's a good size for most home ovens.

That said, there are people who use an oven without any flue at all, and you could try propping the big flue tile over your entrance, to see how it works.

[Tscarborough]

Re: Can you have a flue that's too big?

In a worst case scenario, you could consrict the opening after test firing.

[david s]

Re: Can you have a flue that's too big?

My wife and I are currently in the island of Paros. Among all kinds of exciting things here are some WFO's Seems every house has a chimney for something wood fired. I can't figure out how to post photos onto the forum from my iPad. I can email them but not attach to a post, may have to wait till we return home in Dec.

[Neil2]

Re: Can you have a flue that's too big?

The only drawback might be the depth of your opening. Too long and you will have increased difficulty in working the oven.

[eatingmorefood]

Re: Can you have a flue that's too big OR too small?

Hello Friends,
I have been getting a lot of recycled materials for my oven.
Wondering if a very old 3 ft. piece of Red Clay Drain Pipe ( 4 in .ID, 6 in OD) would work well for a chimney on my proposed 32 pompeii oven ?
It is near perfect condition and was donated.

All my rebar, crushed stone and most other materials so far
was free (most leftovers came from friendly const. sites and a dump)!
thanks,
EatingMoreFood

[dmun]

Re: Can you have a flue that's too big?

A four inch clay drain pipe is not big enough to suck out smoke on startup. You will get smoke staining on your entry. The other concern is that drain pipe isn't refractory material. It's possible that it could crack, but the refractory flue tiles have cracked as well.

I understand all about saving money, but 8" square flue tile isn't expensive.

[eatingmorefood]

Re: Can you have a flue that's too big?

dmun,
Thank you for your expertise, I do not want a mouth full of smoke. I will get the 8 in. flue tile when the time comes.
Best Regards,
Eatingmorefood .....Chef

[david s]

Re: Can you have a flue that's too big?

I'm in France at the moment, after being in Greece, Italy and Switzerland Have seen a lot of ovens on our travels and quite a number of them had enormous flues, they were in fact built in or alongside large fireplaces. The flue and mantlepiece of the fireplace simply doubled as the oven flue. This system also eliminates the extra reach required past the flue entry. Shall post photos when I get back in early Dec as I can't seem to post pics from my ipad, only email them.

French bread is fantastic, but can't say the same for Italian bread.
And Fench keyboards are tedious!

[Lburou]

Re: Can you have a flue that's too big?

snip...I was gifted a piece of industrial strength flue, about 11" square and two feet long. I'm planning on having a standard oven opening according to the Pompeii oven plans, 20" wide by 12.5" high..... snip...Will having a bigger vent and flue screw up the draw? Would love to hear some opinions from the masters, thanks.

How are you cutting your brick? Assuming a clay flue, and if your saw will cut the clay in the shape you have, just cut opposite sides in a way that removes three or four inches of clay, making that side seven or eight inches wide, leaving the final dimensions whatever you want. This would work with a clay tile and a circular saw with the right blade....Trying to think outside the box to support your initial premise of a low budget.

[Tman1]

Re: Can you have a flue that's too big?

David- it'd be nice to see pictures!!