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Forge chimney setup

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Hi. I am at the point in setting up my forge building where I can now fit the chimney. I have 2 meters of 250mm ducting + a cap and am trying to decide the optimum length and fitting. I want to stick with the 1meter section because it will be much less prone to damage in the very high winds I get with my forge overlooking the sea. What is the minimum effective length that will still effectively draw smoke away? I have read a lot of contradictory advice about length and wonder what the consensus was. I also wonder if anyone had used the same kind of hardware i have and if so did you brace the ducting to keep it all secure? I was thinking of running some wire from 2 points on the roof and twisting them around the ducting.




p.s the roof has a very gentle slope, the distance from the forge to the roof is aprox 35cm and the one meter section would extend 65cm not counting the top that adds another 15cm. 


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Generally I've read multiple times from what I consider good sources that you want the top of the chimney ducting 4" ( about 122cm) above the peak of the roof. Also with the rain cap, you want it to about the same gap from the pipe as the diameter of the pipe. Having it closer( more closed off) restricts the draw.

I've had pretty good results with doing that. And I'm using 10" duct pipe. 12" is more ideal. 

I used stainless steel strap to anchor mine. Don't see why wire wouldn't work. I also used sheet metal screws to secure the lengths of duct together. Then sealed the joints with high temp silicone ( over kill as the pipe barely gets all that hot). 

Hope that's helpful. It's what I've more consistently read and am using. 

Nice forge. 

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First thing to X is what if anything does your local code/requirements are for a new chimney. 

3 hours ago, blackleafforge said:

I was thinking of running some wire from 2 points on the roof

 3 points on the roof would be more secure. 

how to figure out chimney height

this is suggested install.

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Talk to a roofer or pick up a how to book at the library. It's a matter of the right roof jack, flashing collar, lapping the roof sheeting in the right order, nothing special about it just follow the directions and apply sealant where indicated.. Home Depot carries just the book for cheap or free

Frosty The Lucky.

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