Go Back   Forno Bravo Forum: The Wood-Fired Oven Community > Pizza Oven Design and Installation > Design Styles, Chimneys and Finish

Like Tree2Likes
  • 1 Post By brickie in oz
  • 1 Post By michelevit

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 01-09-2013, 01:55 AM
spt spt is offline
Peasant
 
Join Date: Feb 2009
Location: New Plymouth, New Zealand
Posts: 25
Default Flue sizing

Hi all, I am building a 36 inch pizza oven and trying to decide what is the best flue size to use. No doubt it has been asked before, but I was wondering if anyone can offer any advice from experience as to whether a six inch or an eight inch flue works best for a 36 inch oven. Also, is there a maximum or minimum height to work efficiently? Any help would be appreciated. Regards Dave.
Reply With Quote
  #2  
Old 05-04-2013, 06:11 AM
Serf
 
Join Date: May 2013
Location: Australia
Posts: 8
Default Re: Flue sizing

Venturi effect

4 inch , any obstacles nearby may cause low pressure areas
Reply With Quote
  #3  
Old 05-04-2013, 02:12 PM
brickie in oz's Avatar
Il Pizzaiolo
 
Join Date: Mar 2009
Location: Whittlesea
Posts: 3,455
Default Re: Flue sizing

Quote:
Originally Posted by sandgroper View Post
Venturi effect

4 inch , any obstacles nearby may cause low pressure areas
The smoke will find the easiest way out which is the door.

A venturi only really works on a closed system without the larger escape hole for the smoke.
__________________
The English language was invented by people who couldnt spell.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
  #4  
Old 05-05-2013, 05:32 AM
Serf
 
Join Date: May 2013
Location: Australia
Posts: 8
Default Re: Flue sizing

In that case any Rumford fire would smoke like a dragon

Principles of venturi according a fire size the flue should draw especially if tall enough.

Try the 8 then
Reply With Quote
  #5  
Old 05-05-2013, 11:52 PM
brickie in oz's Avatar
Il Pizzaiolo
 
Join Date: Mar 2009
Location: Whittlesea
Posts: 3,455
Default Re: Flue sizing

Quote:
Originally Posted by sandgroper View Post
In that case any Rumford fire would smoke like a dragon
Fair enough, point taken.
But in building a fireplace and chimney there is a slow gather of the brickwork above the fire box to coax the smoke to go straight up, which it wants to do anyway due to heat and the expanding volume of the gases.

In an wood fired oven situation the smoke is making a rapid exit for the door, you have to then persuade the smoke to do a right angled turn and go up the flue, making the flue smaller will inhibit this.
Gulf likes this.
__________________
The English language was invented by people who couldnt spell.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Last edited by brickie in oz; 05-05-2013 at 11:55 PM.
Reply With Quote
  #6  
Old 09-25-2013, 08:51 AM
Apprentice
 
Join Date: Mar 2008
Location: san jose ca
Posts: 106
Default Re: Flue sizing

6 inch is perfect for my 36 inch oven.
What makes the smoke move up the flue is the draw. Heat rises so it you can create a draw. The longer the chimney, the stronger the draw.

A draw can be strong enough to move smoke sideways and even downward.
Rocket stoves have flames and smoke move that move sideways and down.

I use stackable 6 inch hvac for my chimney. The longer I make that chimney, the stronger the draw.
Reply With Quote
  #7  
Old 09-25-2013, 09:18 AM
stonecutter's Avatar
Il Pizzaiolo
 
Join Date: Jun 2007
Location: South Carolina,USA
Posts: 1,885
Default Re: Flue sizing

Quote:
Originally Posted by sandgroper View Post
In that case any Rumford fire would smoke like a dragon

Principles of venturi according a fire size the flue should draw especially if tall enough.

Try the 8 then
Conventional draw characteristics change dramatically with outside fire chambers....which is why you can't over flue a wood oven or outdoor fireplace.
__________________

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


Current WFO build -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


When we build, let us think that we build for ever.
John Ruskin
Reply With Quote
  #8  
Old 09-25-2013, 03:33 PM
boerwarrior's Avatar
Journeyman
 
Join Date: Apr 2013
Location: Santa Rosa, CA
Posts: 448
Default Re: Flue sizing

I have a 6 inch flue on my 32 inch oven and it works fantastically. After the oven (and flue) heat up I get no visible smoke out of the front. I suspect the 6 inch flue would work just as well for your slightly larger 36 inch oven. Make sure you do not constrict the air flow prior to it entering the flue.
Reply With Quote
  #9  
Old 11-05-2013, 01:12 PM
SpottedFrog's Avatar
Laborer
 
Join Date: Feb 2013
Location: Australia, Bathurst NSW
Posts: 68
Default Re: Flue sizing

So if I am using a 20cm or 8" flue on a 1000mm oven I should be okay? Does it have to be double walled it is outside completely?
__________________
Cheers,
Rosemary

My build so far

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


Starting out collecting info and materials

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
  #10  
Old 11-05-2013, 01:16 PM
Apprentice
 
Join Date: Mar 2008
Location: san jose ca
Posts: 106
Default Re: Flue sizing

I think the double wall is necessary just for safety incase the flue passes through a building structure. If the oven is located outside and the flue does not pass through a building structure, then a double flue is unnecessary.
SpottedFrog likes this.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Chimney Flue Sizing jbarnes Forum Guidelines 7 09-08-2011 04:41 AM
Cracked Flue davidL Tools, Tips and Techniques 3 04-20-2011 04:12 PM
Cracked chimney flue mfiore Pompeii Oven Construction 1 05-04-2009 02:35 PM
Chimney Flue Question RCANCILLA Modular Refractory Oven Installation 5 04-08-2009 07:47 AM
Flue Chimney Tips Alf Design Styles, Chimneys and Finish 1 08-02-2005 07:07 AM


All times are GMT -7. The time now is 01:56 PM.

Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
2006/10 Forno Bravo, LLC