Flue Size for 30" ID oven

[Lambooni]

Hello,

My oven is all but complete. I am just going through the curing fires now.

I have noticed that a lot of smoke comes out of the front door on start up and as new pieces of wood are placed into the oven. I hoped most of this would go up the flue.

I wonder if this is down to my flue size? I have a 30" ID oven, its a full dome/iglu style with a front flue exit. The flue is currently 5" diameter an about 20" tall.

The majority of smoke does go up the flue but I am worried I do not have enough draw and this will effect my oven temprature and pizza cooking ability!

Thanks in advance,
Adam

[david s]

Re: Flue Size for 30" ID oven

New ovens are always a bit smoky, so just keep firing for a while before you do anything drastic. I use a 5" flue for my oven design but it is only 21" in diam (considerably smaller in oven volume than your 30". About a third the volume actually) I think you should really have a 6" flue. But an alternative you could try is to increase the height of the flue to increase the draw. Another trick is to light a very small fire under the flue, increase it very slowly, then after 5 mins push it back into the centre of the oven.

[boerwarrior]

Re: Flue Size for 30" ID oven

i have a 6" flue on my 32 inch and very little smoke comes out the front once the flue is warm. I have an 8 foot chimney. Are you sure you have a large enough 'transition' from the oven to the flue? That is an issue we see here sometimes. You want to make sure you never constrict the flow of smoke on its way to the chimney

[Lambooni]

Re: Flue Size for 30" ID oven

Boerwarrior,

When you say 8ft do you mean from the exit point of the over to the top of the chimney, or floor to top of chimney.

My chimney is only a couple of feet long from the oven, about 8ft from the floor. It sounds like maybe I need more length?

[Lambooni]

Re: Flue Size for 30" ID oven

My Chimney is now cemented into place but would an expansion help me at all? If I were to cut off the current flue close to the dome, add a 5 inch to 8inch expansion piece, then an 8 inch flue?

[david s]

Re: Flue Size for 30" ID oven

My Chimney is now cemented into place but would an expansion help me at all? If I were to cut off the current flue close to the dome, add a 5 inch to 8inch expansion piece, then an 8 inch flue?

Yes this will work, because your larger diameter will be providing much more power to draw, but the restricted diam length should be as short as possible. It will act like a venturi and the smoke will accelerate through that section.

[boerwarrior]

Re: Flue Size for 30" ID oven

Hi Adam

sorry for the slow response. I have two four foot sections of 6" DuraVent SS chimney pipe secured to a plate on top of the arch - so I am probably about 9 feet high off the floor. The chimney pipe has to get hot before I get a good 'draw' - but once it starts it pulls the smoke nicely!