elkdoc

Coal forge hood design

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Hey folks. Need some input on a decent hood design for my coal forge. I prefer an overhead hood. Any thoughts? Things to consider?

Thanks! 8)

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Give serious look at a side drawing hood elkdoc. I've never seen an over head hood on a coalforge that actualy works unless it has power assist on the venting.
There are those here who will explain it better, but it's my understanding that a big hood has too much of an opening and takes too much cold air with it to draw correct.

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It's not that I'm completely against a side-draft hood per se. However, I do need something relatively inexpensive and easy for a beginner to build. :oops: I know that side-draft hoods draw better, but isn't there an issue with workspace?

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A side draft is the easiest thing to build. One of the simplest is just an opening cut in the side of a piece of pipe and then reinforced with some flat iron. And your fire is out in front of the hood so you have open space on top and 3 sides. The couple times I've worked under a full bell hood it has been in the way for anything big.

There also are plans for a more elaborate side draft hood on line someplace. Someone here will know where they are.

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ElkDoc, Jim's advice is good. I made the mistake of building a very nice overhead hood for my coal forge. It was an offset pyramid of brake formed galvanized sheet metal and had a perimeter frame of angle iron with forged hanging hooks in the four corners to suspend it by. Everybody who saw it loved its looks- the only problem was it wouldn't draw off the smoke from the fire. Unless the hood is very low to the fire you start to pull in a layer of the ambient air around the forge and it seems to form a barrier to the rising smoke which then billows out around the hood instead of being drawn up the chimney. ( This hood even had a power ventilator in the stack.) That hood is now sitting on the floor of another smith's shop. He insists he wants to use it because he likes the look even though I told him it won't work well. I now have a simple side draft hood mounted next to my firepot and it draws really well. (I still use the power ventilator because my stack size is limited.) Your side draft hood can be as simple as an angle cut in your flue pipe to create an opening or as elaborate as your imagination allows.

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Alright... You've got me thinking. Since my shop is small, ventilation is key. I guess a side draft is the way to go. I just had it in my head that it would be more complicated than my meager construction skills could afford.

I suppose I could get rectangular ductwork and cut a hole in the side.

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Thought I'd show off a picture of my homebuilt forge, awaiting a hood. Pine and skip-planed oak frame, steel plate base, cheap firebrick top, OC blower, Centaur firepot. Not too shabby, if I do say so myself.

forge_no_hood.jpg

Now... If we can just get a hood and flue installed, some salvaged metal siding on the walls, and I'm ready to go! :)

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Alright... You've got me thinking. Since my shop is small, ventilation is key. I guess a side draft is the way to go. I just had it in my head that it would be more complicated than my meager construction skills could afford.

I suppose I could get rectangular ductwork and cut a hole in the side.


Yeah, I too have been contemplating as to what type of hood to build myself. I had been planning on a large overhead hood too until today. I just got back from seeing a new friend I have now that has been forging professionally now for 25 years. We got on the discussion of forge hoods when I seen that he was using a side draft hood on his forge as well. I questioned as to how well it worked, so he lit the forge to show me....I was very impressed. It really sucked fantastic. Sucking in this case is a good thing! Really had great draw on it. He had the walls of his shop painted white and they were still white, and it was painted 10 years ago. I am now going to build a side draft for mine.

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Also, if for any reason you get water that comes down the stack it does not end up immediately in your fire pot. :cool: You might also want to consider a low loss high velocity stack cap.

Hope this link will work.

Edited by steve sells
Had another thought to pass on.

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BP1048 Side Draft Chimney
There is a slight tilt to the horz slope to resist rain.


Yep, I agree. If this particular design is made that is the case alright. The one that I looked at today and plan on building one similar to, the stack comes right into the top of the side draft hood and there is not a long horizontal run like in the link you had provided. But yes a valid point.

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I've also been planning a side draft hood for my forge, having changed my mind from an overhead. My only question would be direct wind into the hood. My layout places the hood going out the north wall, but I'm worried about south bound winds. Any suggestions?

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Even with side draft hood you need a significant vertical rise in your stack to drive the chimney effect.  If you end the vertical rise above your roof line (as is typically required by code) and use either a low loss stack cap or weather retention annular termination wind direction shouldn't be a huge factor.  It is only when you have the termination pointing horizontally in the direction of the wind that I would be concerned.

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