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-   -   Help needed! can't get a good draw (http://www.fornobravo.com/forum/f9/help-needed-cant-get-good-draw-17791.html)

MarcMunier 05-24-2012 02:08 AM

Help needed! can't get a good draw
 
3 Attachment(s)
Hi all

First time post but already uber impressed with the skills some of you have!

Building my first oven, all gone quite well until I set the first fire................. the vent I cut in the front arch doesn't draw smoke effectively. (pic1)

I have widened the gap and also chopped some of the internal side of the gap to make it more curved (pic2) but I still get smoke drifting out the front.

However when I block the top of the entrance and put the large chimney on I get a really good draw and the fire roars (pic 3)

Is there something I can change now? I'm currently planning to extend the front section of the arch to encourage the smoke to go up the vent and or building a door which would replicate the effect of the bit of ply I have in place now.

But I'd rather not have to do that as when I would need to access the oven I'll still get a load of smoke in my face :(

Any advice as to how I can not get smoke in my face would be very welcome.

NB the dome hasn't had it's coat of render yet which is why is looks a little tatty..

Thank you in advance

Marc

Mingy 05-24-2012 05:13 PM

Re: Help needed! can't get a good draw
 
Maybe I don't understand, but I believe you need a chimney and a door to get a proper draw. I did not try mine before had a chimney and door so I don't know for sure. I am in the process of building my final door (got the glass today!) so I used double thickness 3/4 exterior plywood for a test/seasoning door. I drilled a few 1" holes in the bottom to let air in.

Gulf 05-24-2012 05:36 PM

Re: Help needed! can't get a good draw
 
That chimney needs to be sealed to where it will not draw air between the top of the arch and the bottom of the chimney. But, for the most part, IMO you need to try preheating the chimney before starting a fire in the WFO :).

Faith In Virginia 05-24-2012 05:49 PM

Re: Help needed! can't get a good draw
 
If that is your first fire. a small fire just to start curing the oven then that is absolutely normal. Once you start bigger fires the heat generated will aid in the draw up the chimney. Right now your smoke is not that hot so it tends to just linger about. Once you get it hot it will want to rise. No worries your oven looks great. Get it cured as you should and I'll bet it will be fine.

Les 05-24-2012 06:24 PM

Re: Help needed! can't get a good draw
 
Marc,

When I built my outside arch, I dropped it about an inch. My thinking was that the smoke would hit it and prefer to back up and out. Not sure how much it helps but the smoke out the entry is a minimum. Once the temps get up it will definitely go out your vent. And as gulf mentioned, ensure that the stack is sealed.

MarcMunier 05-25-2012 12:16 AM

Re: Help needed! can't get a good draw
 
Quote:

Originally Posted by Mingy (Post 132026)
Maybe I don't understand, but I believe you need a chimney and a door to get a proper draw. I did not try mine before had a chimney and door so I don't know for sure. I am in the process of building my final door (got the glass today!) so I used double thickness 3/4 exterior plywood for a test/seasoning door. I drilled a few 1" holes in the bottom to let air in.

So do you need a door to get a proper draw? I saw a post which had a you tube video which had very good draw with no door but was that the exception?

Also I have done a few larger fires(2/3 logs) now and I still get smoke coming out of the front, do I need to shape the vent more?

david s 05-25-2012 03:30 AM

Re: Help needed! can't get a good draw
 
Also new ovens are notorious for being smokey. Once it is dry, and this may take about ten fires it will be less smokey.

brickie in oz 05-25-2012 03:56 AM

Re: Help needed! can't get a good draw
 
Quote:

Originally Posted by Gulf (Post 132029)
IMO you need to try preheating the chimney before starting a fire in the WFO .

Its what his Great Great Great Grandpappy used to do, its a tradition.....:rolleyes: :D:D:D

Jaronimo 05-25-2012 04:24 AM

Re: Help needed! can't get a good draw
 
The smoke will never flow correctly without a chimney. When the chimney is installed you will get some smoke out the front until the chimney heats up a bit and starts flowing upward from that heat. Heat rises, so when the chimney gets hot it actually starts to suck the air up into it which draws in the smoke. The taller the chimney, the more draw you will.

Lburou 05-25-2012 05:49 AM

Five points Marc :)
 
Welcome Marc :)
  • The oven smokes only in the early stages of the fire, after it heats up, it does not smoke so much, expect that to improve when you get a hot fire in there.
  • An air tight chimney will draw much better than your trial fitting does.
  • A 'blast door' is something many of us use every time we light the fire.
  • If you light the fire at the top of a stack of kindling, you may have less smoke in the early stages of your fire, search for 'top down' fire starting.
  • Your oven entry is very shallow, that makes it easy to access the inside of the oven, but a little more tricky evacuating the smoke efficiently.
  • HTH :)
This is my blast door, I use it for every fire:

http://www.fornobravo.com/forum/memb...-door-fire.jpg


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