David Hendley on mon 16 oct 00
I got this e-mail (below) from a friend who is having
trouble with his new Minnesota Flat Top-design car kiln.
The kiln was built according to Nils' newest plans,
except that it has an arch instead of a flat top.
He wants to start tearing out and enlarge the flue and
damper area. Can some of you experienced MFT firers give
him some ideas of some things to try before trying
radical surgery?
>I've fired twice. I get good temp. and even heat but I'm having
>drafting problem.
>The first firing was 24 hrs.
>Changed gas orifice and got better heat in second firing, 26 hrs.
>The draft problem seems to be constriction in flu box damper.
>Full open still gives heavy reduction thru out kiln. Lots of back
>pressure, and black core in broken sample.
>It's reducing too early and there's no control there.
Thanks,
--
David Hendley
Maydelle, Texas
hendley@tyler.net
http://www.farmpots.com/
Craig Martell on tue 17 oct 00
Hi:
I have a 66 cubic ft MFT with an arch. From your description of how your
friends kiln is firing I would think that he's putting in too many
btu's. The low requirement is 660,000 btu's per hour at max input. I use
a bit less than this and my kiln will fire from ambient temp to cone 10 in
12 hrs. If your friend doesn't have the tools to figure out what his
burners are putting out, send me the specs and I can tell. I have the
charts and info to figure it out. If it's not too much gas, then he can
look more seriously at the draft scenario. I'd look at the btu input first
becuz that doesn't require a major overhaul to fix.
later, Craig Martell in Oregon
Tom Wirt/Betsy Price on tue 17 oct 00
First question...what's his stack height?
Tom Wirt
From: David Hendley
Subject: firing problems with new Minnesota Flat Top
> I got this e-mail (below) from a friend who is having
> trouble with his new Minnesota Flat Top-design car kiln.
> The kiln was built according to Nils' newest plans,
> except that it has an arch instead of a flat top.
>
> He wants to start tearing out and enlarge the flue and
> damper area. Can some of you experienced MFT firers give
> him some ideas of some things to try before trying
> radical surgery?
>
>
> >I've fired twice. I get good temp. and even heat but I'm having
> >drafting problem.
> >The first firing was 24 hrs.
> >Changed gas orifice and got better heat in second firing, 26 hrs.
> >The draft problem seems to be constriction in flu box damper.
> >Full open still gives heavy reduction thru out kiln. Lots of back
> >pressure, and black core in broken sample.
> >It's reducing too early and there's no control there.
>
>
> Thanks,
> --
> David Hendley
> Maydelle, Texas
> hendley@tyler.net
> http://www.farmpots.com/
>
>
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>
Nils Lou on tue 17 oct 00
The problem is much more likely the burners than the flue.
"full open" is probably too much gas. Your friend needs to have a way to
determine an efficient flame. he is on the wrong track changing the flue
box as many who fire with that design will tell you. nils
On Mon, 16 Oct 2000, David Hendley wrote:
> I got this e-mail (below) from a friend who is having
> trouble with his new Minnesota Flat Top-design car kiln.
> The kiln was built according to Nils' newest plans,
> except that it has an arch instead of a flat top.
>
> He wants to start tearing out and enlarge the flue and
> damper area. Can some of you experienced MFT firers give
> him some ideas of some things to try before trying
> radical surgery?
>
>
> >I've fired twice. I get good temp. and even heat but I'm having
> >drafting problem.
> >The first firing was 24 hrs.
> >Changed gas orifice and got better heat in second firing, 26 hrs.
> >The draft problem seems to be constriction in flu box damper.
> >Full open still gives heavy reduction thru out kiln. Lots of back
> >pressure, and black core in broken sample.
> >It's reducing too early and there's no control there.
>
>
> Thanks,
> --
> David Hendley
> Maydelle, Texas
> hendley@tyler.net
> http://www.farmpots.com/
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
>
Tjo62@AOL.COM on wed 18 oct 00
My first firings were very long. How gas are you giving it? Doesn't use
much or it reduces too soon.
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