Clay flue ?

[dsm]

Hello again, i was going to use 8" duratech flue on my 39" wfo well now 391/2 wfo it magically it grew during construction but now might be changing my mind and using clay flue what size would be appropriate, would it be a 8x8 flue?


Thanks,
Dave

[azatty]

Re: Clay flue ?

Get 10x10 flue, minimum, for that sized oven, unless you want a really tall chimney. Clay flue goes by outside diameter, not inside, so to get an eight inch cross-section you'll need an OD of 10 inches.

[dsm]

Re: Clay flue ?

Im only gonna go 2 feet high with the flue if that is ok dont really know correct me if i am wrong, i am planning of having a flat roof so a 10x10 would be good your saying?

[Tscarborough]

Re: Clay flue ?

It goes from 8x8 to 13x13 (OD) in clay flues. You can try and find round clay (it is measured ID, FYI), but it is almost as pricey as metal. I do not know what size you need, whatever is recommended by the FB plans, I guess.

[dsm]

Re: Clay flue ?

I didnt know it was that it was almost the same price as metal i was going to use clay to cut back a little on cost .

[Tscarborough]

Re: Clay flue ?

Standard square and rectangular flue is cheap, round clay flue is pricey.

[GianniFocaccia]

Re: Clay flue ?

In California, a 13" square clay flue tile is around $25 per 1' section.

[Tscarborough]

Re: Clay flue ?

It is about 12 bucks a foot here.

[Gulf]

Re: Clay flue ?

25 bucks is about what it cost me for the fire brick per foot for an 8" id section of my flue.

[dsm]

Re: Clay flue ?

Thanks for your help everybody....

[azatty]

Re: Clay flue ?

You should probably plan for a three foot chimney. FB plans call for a 3 foot chimney using 8 inch round stainless pipe. The 10x10 square flue has the same effective cross section as 8 inch round, so the draw won't be the same between 2 feet of 10x10 and 3 feet of 8 inch round. Also, with a flat roof you still have to account for insulation (3 to 5 inches), the roof beams (4 inches), a bit of an air space for ventilation (2 inches) finish material (1 inch minimum), plus a "reveal" at the top of the flue for a spark arrestor if required by local code.

Two feet looks good until you put the roof on, and then it will seem too short. Two feet on my 42" oven clears the flat roof by 16 inches, and that's only because it's sitting on an 18 inch vent transition.