[TheForge] coal forge exhaust system

[Paul N]

Thanks Paul (and Mike)
I was hoping the flue temp several feet away from the forge would not be an issue. How hot do you think it might be 10 feet or so beyond the top of a hood? Some of these ducted blowers move 700+ CFM and are rated for temps around 140*F.  I was hoping that the "dilution" that Mike mentioned would help keep things cool enough.
 
Mike, what kind of air flow would you expect from a squirrel cage, and why is that really different from a ducted fan in this application?
 
I've also been watching for a "cheap" used commercial kitchen exhaust. I'd think that should work.
 Soot can certainly become a problem, and it's probably corrosive as well. I just don't know if it's negligible, a nuisance, or a complete show-stopper.
 
Of course, without measurement, I'm just guessing, and why I asked the larger group... An experiment without an acceptable result makes the whole installation more expensive if I have to revert to a more traditional, unpowered approach.
 
I've only been to Jim's shop once, and I don't recall what his hood looked like. Are you proposing a telescoping or periscope-like flue?
 
Lastly, while I actually considered a venturi type arrangement, I think Dave Brandon tried something like that and was unsatisfied. Too bad I didn't make it out to his place yesterday. Anyway, I think an effective venturi would probably be more expensive than the other approaches.
 
Anyway, I'm sure there are people on this list that have forced air exhausts that work. I'm hoping that I can hear some successes, and even some advice avoiding pitfalls they might have encountered.
 
thanks,
*Paul Novoorolsky
 
 

From: Paul Sperbeck <forge at wi.rr.com>
To: Paul N <crosspein at sbcglobal.net>; Blacksmithing List Sponsored by ABANA <theforge at mailman.qth.net> 
Sent: Monday, November 18, 2013 7:58 AM
Subject: Re: [TheForge] coal forge exhaust system


I think that you would have a real problem with the temperatures and the soot in the coal flue messing up the fan.

If you need to exhaust  without a stack I think that you might be better off with a venturi extractor.

Use a fan drawing outside air to feed a nozzle injecting a high velocity air stream into a lager stack and use the vaccum produced to create a stack draft.

Perhaps you could build something like Jim Ribordys forge hood, but allow the pipe through the roof to move up as well. This would give you the stack you need when you are forging and allow the stack to lower down below the roof line when you aren't working.

paul

On 11/18/2013 07:43 AM, Paul N wrote:
> Has anyone on the list tried using one of these (or similar) ducted exhaust systems for a coal forge?
> http://www.pexsupply.com/Fantech-FG8-FG-Series-Round-Inline-Exhaust-Fan-8-Duct-461-CFM
> 
> I'm finally setting up a permanent shop, and was hoping not to have to run a stack high up above my roof ridge line. If I can run a forced exhaust system out my gable wall, I can save some money, as well as avoid having a tall stack on the roof.
> 
> These things are all for sale all over the place, with some pretty significant CFM numbers. I'm concerned about the temperature as well as the volume of air moved. I don't think I need a whole lot of static pressure, but I do want to be able to exhaust coal fumes without starting the place on fire.
> 
> Thanks,
> **Paul
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paul
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