chimney opening size help and advice

[dazag12]

I have built a 36 inch dome and an opening of 18 inch with a current chimney size of 10 inch wide 2 1/2 inch deep and 36 inch high but I don't seem to get good airflow would increasing the chimney width to 15 inches help if any one can advise please

[RandyJ]

How big of a chimney do you have? My guess is that you need a 8" and then you need twice as much of a opening as what you have. Because you want the chimney to be the smallest part of the system. So right now you are at half that. If you are doing a 6" chimney then 15" wide would help as you need 28sq" at least for the opening.

Randy

[david s]

I have built a 36 inch dome and an opening of 18 inch with a current chimney size of 10 inch wide 2 1/2 inch deep and 36 inch high but I don't seem to get good airflow would increasing the chimney width to 15 inches help if any one can advise please

A 6" round flue pipe is adequate for a 36" oven and has a cross section of around28 square inches. Yours at 10 x 2.5 is 25 sq inches, not much under. Could it be that your oven is new because a new damp oven is always smoky. If this is the problem the remedy is more firing.
Dismantling and rebuilding the chimney is a fair amount of work. Increasing the chimney height is an easier way to increase the draw.

[Novaslo]

Your build looks very similar to what I did and also the mistake I made. The comment David is making says it....the flu area leading up to your flu pipe needs to be larger. Think of it as an Entry cavity. Smoke enters the cavity and then goes up into the flu. Done that way the problem is solved. Right now you have a round hole and no cavity for the smoke to go up. It will still draw but it just won't eliminate the smoke the way you like and the front of your oven will get black and stay that way.

If you still have time - re plan your flu entry and raise your Pipe - create that cavity of space that leads up to it. I think that is a lot of work and if you look at my build you will see that I did the same thing.
Ultimately I created a new flu in my box enclosure that keeps my front facia from turning black. It's a long story on my part but it worked.

Good luck- I hope I am not confusing things further for you.

[dazag12]

Your build looks very similar to what I did and also the mistake I made. The comment David is making says it....the flu area leading up to your flu pipe needs to be larger. Think of it as an Entry cavity. Smoke enters the cavity and then goes up into the flu. Done that way the problem is solved. Right now you have a round hole and no cavity for the smoke to go up. It will still draw but it just won't eliminate the smoke the way you like and the front of your oven will get black and stay that way.

If you still have time - re plan your flu entry and raise your Pipe - create that cavity of space that leads up to it. I think that is a lot of work and if you look at my build you will see that I did the same thing.
Ultimately I created a new flu in my box enclosure that keeps my front facia from turning black. It's a long story on my part but it worked.

Good luck- I hope I am not confusing things further for you.

hi journey man have you got pictures of your build I can take a look at please also thanks for your speedy replies every one