Flues for your Wood Fired Ovens - what they do and how to use them
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- čas přidán 15. 01. 2019
- A technical talk about flues on your wood fired oven - do you need them, what do you need and how to combat any problems you might have with them.
Any questions you've got about them, just let us know in the comments below.
Happy cooking
David and Holly
Manna from Devon Woodfired Cooking School
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In this case the chimney is hot, and in use.
Great idea for a cold chimney. I’ll try that next time I start cold.
Here is a trick that works very well to induce a draft in a cold chimney. Before setting your fire use a hair dryer and blow it up the chimney for several minutes warming your chimney and inducing a draft. To check if you have a draft light a match and hold near the chimney opening if the flame/smoke rises into the chimney you are good to go...if not run the hair dryer for another minute or two....
Super helpful. Thank you!
Pleasure - so happy you found it useful. Happy cooking, David and Holly
Thank you
Thanks Paul - hope you found it useful
A very detailed and helpful video (like all of the others). It will certainly help me to get to grips with my new wood oven. Thanks for the great content!
thanks so much for your comment Miles - we're delighted you found the video useful. Enjoy your woodfired cooking, best wishes, David and Holly
This was so helpful. We built our own oven and it works pretty good but the flue does need some work. Now we know how to make it better. Thanks for the info..
That's great Renee; really happy you found the video useful. Happy cooking! David and Holly
Excellent video! I'm having difficulties getting an easy route for the flue out of my new woodfire oven which is going to be installed inside of a commercial building. Just too many direction changes in the way out, im affraid looses will affect the proper flow. Have you seen any flue installation with an exhaust fan that ensure that fumes are pulled out as is supposed to?
Hi Luis, thanks for your comment and we're delighted you found the video useful. For a commercial venture you should really be taking advice from a professional flue engineer. Access hatches can be built into flues to allow for cleaning where access is difficult. Hope that helps; best wishes and good luck with your new venture, David
Very informative video...is there an ideal flue width/circumference for wood fired oven? I plan to build one with a 48" base dome. Is 8" round flue opening good?
thanks so much for your comment - the best advice we can give you is to check that out with a woodfired oven building expert or something like a facebook group with members who build their own.
Thanks for the video! I'm about to open a woodfired pizza truck and am still having issues with smoke and alot of heat coming ouy the front of my rossofuoco woodfired oven. Its made of stainless steel and refractory fire bricks on the floor. The chimney size is 4 ft high. I think i may need to increase it more. Do you have any other suggestions? Was thinking of trying a daft booster fan but I thought it may pull too much heat out of the oven. I also thought of putting a stationary fan blade in the flue in hopes it will draw better. Any suggestions are greatly appreciated! I could send you pictures if you like
Hi Josh, I think the issue with steel ovens (and sometimes with masonery ovens too) is that the entance to the flue, the smoke throat, is very narrow. If the oven is running with a smal ire the flue works fine but with a bigger fire it tends to spill some smoke into the work space. For domestic cooking a small fire is usually all thats required, even for pizza. In a commercial setting you may be running the oven harder and hotter than its really designed for. Hence smoke and heat in your truck. Improving the draw with a fan could help with the smoke but probably won't help keep you cool.
I have found that these ovens are often used with ore fire than is actually necessary. They tend to be very effecient at reflecting heat inside the oven and need less fire than a masonry oven. You could try running a smaller fire and see how that effects your ability to cook multiple pizzas.
Hello, great video! I’m in the middle of a perlite pizza oven build and I’m pretty set on using a 60cm piece of 100mm copper pipe I have laying around. Do you think it’s sufficient as a flue? Oven is nearly 90cm internal. Will be under cover outside under a small gable roof. Cheers
Copper is not recommended for flues because it conducts heat well so will carry heat to your roof and provide no protection if touched. It also discolours easily. However, for an outdoor oven it'll do fine as long as you protect the roof where the flue passes through it. If in any doubt always wise to ask a heating engineer.
@@mannadavid thanks for the reply. The oven is outdoor and I’m not too concerned about discoloring. Also I wasn’t going to pass it through the roof. Just going to sit under it about 50cm away from the metal roof. Probably best to go through the roof but I wanted to see how it goes before I start cutting the roof. Do you think 4inch pipe is wide enough?
I’ve just finished my oven build and am onto the flue next. I’ve had to put a few bends in the flue to get it out where I need it and will have an overall length of about 3.5 metres. 3 questions (sorry), will the overall length be too much? The first section straight up off the oven is 630mm, is this enough? How hot would the outside of the flue get towards the backend if I’m using a single wall, 6” stainless? Last question because I may need to adjust the last lengths based on the heat for a fire risk.
Thanks so much!
Hi Frank. Thanks for your message and great to hear you've finished your oven and are ready to cook. The best advice we can give you is to invite a specialist flue engineer round to check what you've done and give you advice on site where they can really see what's going on. Best wishes and happy cooking, David and Holly.
Your video is just what I needed a few weeks ago, lol. I tried smoking meats for 10 hours in my brick oven that usually holds heat real well. It was early January, mostly outdoors, windy,... I ended up having to spend 20 hours with more fire than I intended to get er done. It did come out great except for some fringe that was on the fire-side. Was thinking I might need a damper. I do have a door that can plug it tight up front, but, it has a tall flue and I think it is venting heat too fast this time of year compared to nice summer weather. Learning a lot. Thanks for the tips :-)
Hi Kelly. Great to hear from you and really glad you're finding our woodfired videos useful. More coming Thursday! Happy cooking. David and Holly
Great video. I am new to a wood fired oven and had my first burn this weekend. I found I was getting flames coming through the flue. Should I slightly close the dampener next time?
It’s a clementi oven.
Hi James. You probably had too much fire in the oven. That type of oven should only need a relatively small fire to give you all the heat you need. If you close the damper it will force smoke and flames out of the front of the oven so definitely keep it fully open when you have flames in the oven. Try it with less wood as a first option.
@@mannadavid Thank you for the advise, I am loving the videos and going to try some other non pizza related recipes soon!
@@jamescoath7302 great - do let us know how you get on
I have a pizza oven fitted in an alfresco area (under stairs) with the flue coming up using 2 X 45 degree elbows to get out from under the stairs (all stainless) and up 1.5 mtrs. The oven is very difficult to light and we get a lot of smoke from the chimney and from the doorway. The flue cap is next to the corner of the upstairs wall of the house (approx 2mtrs below the gutter and 400mm from the corner of the house). How high above the gutter does the top of the flue need to be? If I was to have the top 700mm above gutter line, then the overall flue length would be approx 4mtrs in length. Hope you can help. Regards Lawrence
Hi Lawrence - to be honest it's best to get a local flue engineer to come and give you specific advice. Best wishes and hope it goes well, David
Great help guys, I built my oven and too much smoke comes in, what can I do? I’ve extended the chimney, worked a bit. When I cover the front entrance a bit , the smoke stops, any tips? Cheers guys..
Hello to you in Belize. It's difficult to say what your specific problem might be without a lot more info but here are a few things which might generally be worth looking at:
- is your wood dry, i.e well below 20% moisture content. Wood with too much moisture creates a lot of smoke.
- is the wood cut small enough. Burning large pieces of wood in a small oven creates insufficient heat to burn cleanly.
-is the flue entrance clear: any impediment to smoke entering the flue may cause turbulance around the entrance and means smoke cannot be drawn into the flue.
-is the fire too big for the flue: too large a fire may overload the flue.
to slow down the fire cover the lower part of the entrance to reduce air being drawn into the oven.
-is there any downdraught? in valley bottoms, between buildings and in other circumstance flues may be subject to downdraughts which reduce the ability of the flue to get rid of smoke.
- have you got the right cap, some flue caps are designed to keep rain and maintain some draught out but are not for use with live fire.
I hope that helps but if you can send us some photos we may be able to shed through some light on your particular problem. Best wishes, David
Thanks so much , much appreciated will send photos , cheers Neil..
Hi,
I have a pizza trailer. Down draft seems to be the problem. The slightest breeze to gusty wind, the more wind the more problem.
I can not add length to get more draw.
Is there another solution? I was thinking about changing the cap. What would you recommend?
Adding an anti downdraught cowl is probably the solution. These disperse the pressure differential caused by wind blowing across the flue and prevent turbulance in the flue pipe.
I’m trying to install a twin flue outside through a corrugated metal roof. What height should it be? Thanks
Hi Sabrina, I'm afraid I can't comment on specific installations. Generally speaking there aren't currently regulations covering a flue for a woodfired oven in a simple outdoor structure in the UK. I have a flue through a roof of a gazebo which extends about 50cm above the roof and which has been working fine for years. If it's attached to your house then I would highly reccommend consulting a qualified flue installer as building regulations will apply.
I've just built an outdoor pizza oven and designed it with the flue coming out of the top of the dome 🤡😖 - the (at least partial) saving grace is that the flue has a damper/shutoff. Obviously if I had my time again, I'd have designed the oven differently, i.e. with the flue at the front and lower than the top of the arch - but it is what it is, and I'm wondering how best to manage it and get it up to temperature? Presumably get a vigorous fire going with the damper half-closed, and then close the damper completely to retain the cooking heat? Thanks!
Getting the oven up to temperature shouldn;t be too much of a problem. Light the fire with the flue wide open nd let it get burning nicely so the flue is drawing well before closing it partially. Play with how much you close it so the flue contines to draw exhaust fumes and doesn't smoke from the door. Sread your fire more widely around the oven to get heat into the walls without losing too much up the flue.
If you intend to cook without fire then there is no problem because you can completely close the flue to cook. However, if you intend to cook with a fire burning, as for pizza and other quick dishes, you will need to keep the flue open at least partially. In this case you will need more fire burning to adjust the heat lost up the flue. You'll use more fuel but apart from that it should work ok.
@@mannadavid thanks so much, very much appreciated. Am still kicking myself I didn't build it the optimum way, albeit it was in quite a restricted space so a longer oven would have been tricky. In doing the initial curing light-ups, as you say, it's got up to temperature no problem, but keeping it that way has been the challenge
Will follow your advice and let you know how it goes 🙏
Is there a formula for determining how wide a flue and how long a flue I would need vis a vis the space inside the oven?
Almost certainly but a heating engineer would have that level of knowledge and not a chef/user like me. You could look at wood burner installation websites where you'll find various formual for calculating the size of flue required by stoves of different sizes.
Is the hottest part of the flue, the very top where the smoke is coming from?
The flue will be hottest at the bottom where flames like the base of the flue. The flue will get progressively cooler further from the oven. The gases leaving the flue can still be very hot so make sure it is at a distance from overhanging trees, gazebos etc.