Venting questions.

[ragazzo impasto]

Hi my name is Bill and I have become a WFO addict. i Started my build before finding the site and with Gulf’s help have corrected the dimensions of the oven stand and raised the hearth to a better height. I have finished the 36in dome and inside arch which is not nearly as good looking as the amazing ones I’ve seen on this sight. I knew before I started it wasn’t as easy as you all made in it look.

I was hoping to get some input on venting before starting the outer arch. I placed the oven under the edge of a pergola for shade and protection from hot Sacramento sun as well as winter rains. I was considering using 30 degree angles to take the vent out from under the pergola but because of the “extra” height this no longer appears to be an option (I would need 45 degree offsets).

Everything I’ve read says a straight vent is better anyway. I planned on using about 6 feet of 6in double wall pipe from FB and going though the plywood and shingle roof of the pergola. This should take me about 3+ feet above the roof. I called FB week before last with questions about the extra parts needed to go through the roof and am still waiting for a response.

In in the meantime I’ve been surfing and have found triple wall duraplus cheaper than the Dura-Vent double wall from FB. Both are stainless steel and it appears the duraplus is better then dura-vent or am I missing something? Would like to give FB business for being a wonderful host of this site and forum but if the duraplus is safer...

it it appears I need an anchor plate, 2 sections of 3’ foot vent (duravent or duraplus), a vent cap, roof flashing, a storm collar and a tube of high temp caulk. Am I missing anything?

How do you recommend attaching the anchor to the chimney? I plan on cutting a inlay on top off the chimney and was thinking about cementing all thread post or using cement anchors in the chimney to match the holes in the anchor plate. Or do i not worry about bolting it down just mortar bricks over the edge of the flange?

Looking forward to your guidance. Thank you in advance.

Bill

[Gulf]

Hi Bill,
I'm wondering what kind of fire brick that you are using for your build?

[ragazzo impasto]

The firebrick are from a local manufacturer HC muddox - they are medium type and come in 4 colors. I opted for the standard color for the hearth and darker for the dome. They are imperfect or seconds so they go nicely with my imperfect cuts. The other advantage is the were only 30 cents each.

[ragazzo impasto]

Do you have a concern?

[rwiegand]

You can download extensive installation guides from the Duravent site that will show you all the requirements and parts you need for roof penetration and chimney support. You should then be able to order them through FB if you choose.

Main difference in the triple wall vs insulated double is the outside diameter, the triple wall being bigger. Both work similarly.

[Gulf]

Do you have a concern?

Not now. At first glance I was conserned that they may be used silica brick. After your reply, I went to H.C. Muddox's site. I wasn't aware that they had designer colors for clay fire brick nowadays. Though, watching for signs that the dome is clearing may be interesting with the ebony color. But, 30 cents a piece, Great score!

[mongota]

In in the meantime I’ve been surfing and have found triple wall duraplus cheaper than the Dura-Vent double wall from FB. Both are stainless steel and it appears the duraplus is better then dura-vent or am I missing something? Would like to give FB business for being a wonderful host of this site and forum but if the duraplus is safer...

it it appears I need an anchor plate, 2 sections of 3’ foot vent (duravent or duraplus), a vent cap, roof flashing, a storm collar and a tube of high temp caulk. Am I missing anything?

How do you recommend attaching the anchor to the chimney? I plan on cutting a inlay on top off the chimney and was thinking about cementing all thread post or using cement anchors in the chimney to match the holes in the anchor plate. Or do i not worry about bolting it down just mortar bricks over the edge of the flange?

Looking forward to your guidance. Thank you in advance.

Bill

Bill, first, the choice of pipe. With the exception of comparing the two grades of stainless, the following is all my opinion.

Before even going to 3-wall versus 2-wall, I'd consider the grade of stainless. Personally for my oven, I'll have an 8' vertical run of chimney pipe. Once this is in, I want zero concerns over maintenance or aesthetics. Different grades of stainless steel CAN rust. Two of the more common are 304 and 430, 304 is a better quality stainless, and that's why I chose that. If you're in a store shopping, a way to tell the difference is with a magnet. 304 is non-magnetic. Due to the content in the metal, 430 is ferromagnetic. 430 can rust over time.

Also look at the wall thicknesses. A thicker wall will generally perform better over time than a thinner wall. So I recommend you compare the two; the grade of stainless used for the pipe, as well as the thickness of the metal used in the outer and inner wall material. Two of the more commonly used thicknesses are .016" and .020", a thicker inner liner should handle the thermal stress well, and a thicker exterior wall should weather better and not be prone to dings.

The parts to make up your chimney, what you listed sounds about right. While many components have a "twist lock" feature to join components, you may need a ring clamp to physically secure the two pipes together as well. Depending on your build, you may want to consider some sort of lateral support for the chimney pipe. Check the specific pages for whichever pipe you choose.

For securing the anchor plate, both methods you mentioned have been done. Personally, I chose to use anchor bolts to secure my plate to the brick. I drilled four holes in the plate versus using the factory punched holes so I could locate the anchors specifically where I wanted them (mid-brick), and used 1/4" anchor bolts. Also optional, I ran a heavy bead of RTV between the anchor plate and the bricks.

[ragazzo impasto]

Thanks Rwiegand, Gulf, and Mongo. Although Gulf I didn’t get much sleep after your brick question. And still not sure what you mean by the dome clearing.

Mongo I thought there might be different “grades of SS. Over the years I’ve had bbqs that had a tendency to rust more than others. Thank you for the explanation.

That being said both dura types sound like they are inferior, being 430. I found three other brands on amazon - Ecovent, Shasta, and Selkirk(Probably more) I’m researching. They all appear to be 304 but not yet sure of the thickness.

The FB plans for a 36” dome call for 6” pipe. Is bigger better? (Now that’s something I’m afraid to ask my wife). Would it be better to use 8”?


Thanks again all.

[Gulf]

Sorry Bill,

I did not mean to cause sleep loss . You are just fine with your choice of brick. At 30 cents each, that would have been my choice also. When your oven is finished, stick around the forum. I'm sure that there will be others in your area that will want to find out your source for fire brick seconds at that price.

"Clearing the dome" refers to what happens when the fire brick get super heated. (The dome brick will get very sooty while starting a new fire in a cold oven) The soot will start to burn off when the oven is nearing that superheated temp. It will start to burn off near the top and progress all the way down as the oven gets to pizza temps. You may still be able to see this even with the ebony colored fire brick. I'm not sure. That is above my paygrade. However, the mortar joints will definately show a difference in color. In a few weeks, you will be the expert on that .

I'm looking forward to your progress

[UtahBeehiver]

6" is the recommend size for oven up to 36". I am not advocating DuraVent over other brands ( I actually used Selkirt double wall pipe) but there have been hundreds of FB and forum ovens that have used Duravent and I have never seen a posting about rusting issues. So it is a matter of builder preference and budget. The only thing I would add to your parts list is to make sure the chimney cap has a spark arrestor in it, sometimes this is an option with caps (but if you look closely, a spark arrestor is really just wire mesh just inside the outlet, I just added a ring of wire mesh in my cap) which by the way is a Duravent cap.

[ragazzo impasto]

Thanks all. I haven’t accomplished much this week other than cutting the first few rows of the entry arch. Temps in the triple digits. Visited your three sites awesome work. Gulf looks like you have a brick chimney. Mongo I really like the form idea for the transition. And Utah Russell love the inlay for the anchor plate. Russell any problems with not closing or leaving a gap in the middle arch? I was thinking I would have to complete both front and middle arch’s using the 2.5” sides giving me only a 4 inch wide opening (9-2.5-2.5) by maybe 10” to get the air flow I would need.

i believe all of you have 42” and longer necks than mine. I’m going to have to transition from a 4 x X rectangle to a 6 “ circle. Any other good pictures of arch to vent transitions you could recommend looking at?