[TheForge] photos under "inexpensive recuperative forge"

[Jeffrey Polaski]

>The way it looks to me the 'recuperative' part of your 
>forge is the fact that you are drawing in hot combustion air from the 
>area above the door where the heat drifts/blows out? Wouldn't this hot 
>air have less oxygen than cooler air? Wouldn't that actually be 
>reducing the efficiency of your burner?
Uh, I'm not sure I understand the issue here... 

Oh, I think I understand what you're saying now... You're saying that it
looks like there could be some burning flame sucked out the recuperative
port, leading to a loss of efficiency, right? 

Looking in the forge, there is enough pressure to make a normal flame,
with nothing getting "sucked back". If I hold my hand over the exhaust
port, it's a fairly gentle flow, so I know there is some hot air flowing
through. And I can see the bottom couple of inches of the outside pipe
glow, so I know *that* is getting quite hot.

I use an opening that's about 5" square when I work. Right now the front
of the forge is just a pile of bricks and a piece of ceramic board, so I
can adjust it if I need to. 

I think if I closed off the forge so that the burner was the only
exhaust it would get a lot hotter (I'm going to try that in the future).

One thing I think I forgot to mention in the posts is that I use a
blower. It'll work without one, but a blower makes it a lot more
efficient. 

I don't have a good way to measure the heat, but once it's really warmed
up I can't put a bare hand near it. If I put a leather welding glove
near the opening the glove will smoke and start to discolor in one
second. That's with propane running at 10psi through a small mig-tip
(IIRC 0.027"). I'm not sure how hot that is, but it's hotter than the
first forge I had.

Speaking of which, I was thinking that I could bet a better idea of how
hot the thing gets by putting in a cup of water and seeing how long it
takes to boil away. Maybe just stick the water in a soup can, or
something no too heavy. Try it once with the recuperative part plugged
up, and then once without, and see how it goes. It wouldn't be exact,
but it should give me a good idea. 



Jeff Polaski
Research and Graduate Studies Webmaster
University of California, Irvine
http://www.rgs.uci.edu/
949.824.6363
-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of
schade at acegroup.cc
Sent: Friday, July 21, 2006 11:32 AM
To: Sponsored by ABANA
Subject: Re: [TheForge] photos under "inexpensive recuperative forge"

Jeff,

Glad to see that the photoaccess site worked for you. I took a look at 
your pictures. The way it looks to me the 'recuperative' part of your 
forge is the fact that you are drawing in hot combustion air from the 
area above the door where the heat drifts/blows out? Wouldn't this hot 
air have less oxygen than cooler air? Wouldn't that actually be 
reducing the efficiency of your burner?

Maybe I am seeing this all wrong?

Bob
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On Jul 20, 2006, at 7:57 PM, Jeffrey Polaski wrote:

> I just posted the picture of the "restuperative" forge under the
> "Inexpensive Recuperative Forge" album.
>
> If there's any questions, please let me know.
>
> Jeff Polaski

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