Forno Bravo Forum: The Wood-Fired Oven Community

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-   -   Smoke (http://www.fornobravo.com/forum/f8/smoke-20246.html)

Massimilliano 12-24-2013 09:23 PM

Smoke
 
Hi
I have just completed my oven, which is loosely based on the Pompei.
I am in the process of curing it and am not having a good time of it.
I have used a 6" dia flue, which is surrounded by a 9" clay pipe. The space between the flue and pipe is filled with loose pumice to act as insulation for the flue. The flue is 24" above the arch, which is about 8" thick, giving total flue length of about 32".
The problem is that smoke comes roiling out of the opening, covering me in smoke. The smoke is so bad that it fills up my house. I have to close the windows and doors but it still gets in.
If all if the smoke went up the chimney I think the problem would be less noticeable.
Can anyone offer advice? Will extending the flue make any difference? Note that I do not have a smoke chamber. The flue comes straight out of the arch.
The way it is going I don't think I will use this oven much, if at all.
It is really quite unpleasant.
Max

brickie in oz 12-24-2013 09:57 PM

Re: Smoke
 
Quote:

Originally Posted by Massimilliano (Post 167288)
Hi
I have just completed my oven, which is loosely based on the Pompei.
I am in the process of curing it and am not having a good time of it.
I have used a 6" dia flue, which is surrounded by a 9" clay pipe. The space between the flue and pipe is filled with loose pumice to act as insulation for the flue. The flue is 24" above the arch, which is about 8" thick, giving total flue length of about 32".
The problem is that smoke comes roiling out of the opening, covering me in smoke. The smoke is so bad that it fills up my house. I have to close the windows and doors but it still gets in.
If all if the smoke went up the chimney I think the problem would be less noticeable.
Can anyone offer advice? Will extending the flue make any difference? Note that I do not have a smoke chamber. The flue comes straight out of the arch.
The way it is going I don't think I will use this oven much, if at all.
It is really quite unpleasant.
Max

A 6" Flue is on the small side of things.

Post some pics.....

david s 12-25-2013 01:17 AM

Re: Smoke
 
Max,
What is the internal diameter of your oven? Your 6" flue may well be adequate depending on your oven size. If the diameter of your flue is ok then there are other causes of the oven smoking up.
1. All new (wet) ovens have a tendency to be smokey until they're dried out.
2. Damp wood is also a no no.
3. Overloading the oven chamber with fuel.generally
4. The entry not providing sufficient volume for the smoke to collect before exiting out the flue pipe. Think of an inverted funnel.
A 6" diam flue is good for up to a 36" diam oven, any larger needs an 8".
My oven is only 21" in diam and has a 5" flue that is more that adequate.

stonecutter 12-25-2013 02:47 AM

Re: Smoke
 
Assuming you have a dry oven, and you are burning dry wood, there is another consideration.

Inside ovens are subjected to negative pressure, unlike outside ovens. Does this problem always happen? If it does, you need to equalize the pressure in the room were the oven is.... Crack a window, install a fresh air intake, do not run exhaust fans, etc.

Tscarborough 12-25-2013 08:00 AM

Re: Smoke
 
And especially in an indoor oven start with a small fire to heat the flue, like a couple pieces of paper held up to the flue to burn.

shuboyje 12-25-2013 09:28 AM

Re: Smoke
 
Pretty sure he is saying the oven is outdoors and the smoke is coming into his house. Just sounds like a new oven with a less then optimal vent to me.

stonecutter 12-25-2013 09:54 AM

Re: Smoke
 
Quote:

Originally Posted by shuboyje (Post 167300)
Pretty sure he is saying the oven is outdoors and the smoke is coming into his house. Just sounds like a new oven with a less then optimal vent to me.

If that is the case then agree, it's most likely inadequate venting and flue issues.

brickie in oz 12-25-2013 01:33 PM

Re: Smoke
 
I read the post as the oven is outside and the smoke makes its way into the house.

I dont know who came up with the 6" flue size being adequate for any sized oven but it is obviously too small going by the number of smoke complaints that have appeared on the forum over the years.

Using the 9" clay pipe for the flue would have been the better option.

You cant over flue a wood oven, its not like a fireplace and chimney where the smoke is going vertically straight from the heat source.

david s 12-25-2013 03:19 PM

Re: Smoke
 
Quote:

Originally Posted by brickie in oz (Post 167302)
I read the post as the oven is outside and the smoke makes its way into the house.

I dont know who came up with the 6" flue size being adequate for any sized oven but it is obviously too small going by the number of smoke complaints that have appeared on the forum over the years.

Using the 9" clay pipe for the flue would have been the better option.

You cant over flue a wood oven, its not like a fireplace and chimney where the smoke is going vertically straight from the heat source.

I agree, but the required flue size depends on the size of the oven. Until th OP tells us the size of his oven discussion on the appropriate size of his flue is uninformed.

Tscarborough 12-25-2013 03:46 PM

Re: Smoke
 
Flue size really has no direct relevance to oven size, it is related to door size. The flue has to be in proportion to the door, 10-15% is the normal range, depending upon the tallness of the stack.

A round 6" i.d. flue gives about 10 SqIn of cross section, so it should be fine for an opening of 100-150 SqIn, again, depending upon the height of the stack.


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