kiln ventilation advice sought (long.........)

updated sun 18 jan 98

Don Kopy on thu 15 jan 98

Hi everyone,

I need a new ventilation system for my glaze kilns (10 cubic feet). They have
always been in a seperate room with a fan mounted in the ceiling above. We
still got some fumes from the paraffin, as it billowed out between 250 and 600
degrees F. These kilns were also a walk across the driveway, so not very
efficient (50 ft. away from the glazing area) then back another 75 ft. to
finished inventory storage. This room has had to be renovated and the old
vent removed. It is now the time to move the glaze kilns into the main studio
building (two stories, each 900 square feet each with the ground floor having
twelve foot high ceilings). Moving the kilns into the ground level of the
studio will in effect remove 60 feet from the critical path. I had always plan
to do this at some point, this is the week to do it.

I did design a hood vent system using the formulas found in the book
"VENTILATION" A Practical Guide for Artists, Craftspeople, and Others in the
Arts by Nancy Clark, Thomas Cutter, and Jean-Ann McGrane. I brought the plans
drawn up using the specifications layed out in this book to a local heating,
cooling and ventilation company. They liked the design and would be glad to
install it coming in somewhere between $5,000 and $7,000. Sigh.... on to plan
B.

I would like to get a direct vent system for each kiln that **will work** for
each kiln.
I currently have a Bailey direct vent, and Vent-a-kiln that are on the bisque
kilns. They see lots of heavy use. They have each needed to be rebuilt several
times. The Bailey, in my case, is unable to maintain negative pressure in the
kiln making the studio uninhabital above 1,000 degrees F. I have upgraded the
Bailey to 100 CFM in an attempt to remove the sulphurous fumes from the studio
and this has proved inadaquat.

One of the differences is that the Bailey does not use any fresh air from the
room. This is, in my opinion where the Bailey system looses it's power. It
overlooks the venturi effect of the rushing air to induce the flow of fumes
out the vent. While using the Bailey vent, I have measured CO levels up to
17PPM. While OSHA has determined this a safe level, my headaches tell me that
I may be particularly sensitive to it. The Bailey has been rebuilt so many
times that the only original parts are the cord/plug, and the frame that holds
the motor. The vent-a-kiln has melted in the past (if this happens to you know
that a metal transition is now being used and you should ask for a
replacement). and undergone about 4 changes in design to date to make it work
adequately on the smallest kiln I have which is 7 cubic ft. I can't see it as
being able to capture all the paraffin fumes as they burn off in the kiln.

I have received the information on two vents that I have never used and have
some questions from those who may have had experience with them.

I would really like to be able to adjust the vent so It can be on full, or
whatever power is appropriate to vent ALL THE FUMES. Then once the wax is
burned off I would like to be able to cut back on the CFM from the kiln. I
think ithe effect on the length of time to achieve maximum temperature in the
kiln would be minimized. So I would like higher power until the wax is burned
off, then back it off to a balance of what is needed to do the job.

I have never found any liquid wax emulsions that compare with the resisting
properties of paraffin. I like the wax, and I really do not want to change
over to another type of resist. We will now be working side by side with these
kilns and the fume removal **must be complete**.

Due to line drop problems I need to stagger the firings so that only one can
be on High at a time. I know that perhaps the electric company could probably
fix the line drop. Once they saw the set-up it would bring in the **demand
meter**. This something I would prefer not to have. My meter could double as a
CD player. I solved the problem by schudeling the firings to insure maximum
available voltage near the end of the glaze firing.

1- One choice is the Orton "Kiln Vent". I have heard many good things about
this system. I am confident in Orton's products and expect it to be well
built. I am unsure that it will be capable to capture the fumes from the
paraffin. I spoke with Dale Fronk at Orton. He was one of the designers of
their patented down draft system and they have issued a license to Skutt and
L&L who manufacture their own versions of it. The specifications are as
follows; CFM of blower 79 CFM Mr. Fronk advised me advised me that if the
draw is insufficient that I could experiment with drilling more holes than is
normally recommended. The lid and bottom holes should be kept to a ratio of
1-2. Each 1/2 inch hole in the floor will cause 1 CFM to be removed from the
kiln. He also said that I could "cover up some of the holes in the Plenum with
duct tape" to increase the draw from the kiln. The one thing that always
bothered me looking at this vent is the fact that after the fumes have left
the kiln they are put under positive pressure. One the basics of ventilation
is that fumes should always be removed under by putting them under negative
pressure. In that way, you are *pulling* the fumes out rather than pushing
them. Positive pressure will result in *pushing* the fumes out of any leaks in
the duct, rather than pulling fresh room air into any leaks. It relies on
aluminum duct which I need to replace several times a year because of the
corrosive nature of the fumes. I have even gone through two pieces of
**stainless steel** "Flexaust" (SP?) vent pipe. The maximum kiln size to be
effectively vented is claimed to be 14 CF.

2-The second choice is the VENT-TORR made by L&L. It's produced under license
of the Orton Jr. Ceramic Foundation.

It's advantages are as follows; blower rated at 130 CFM, It can be side
mounted giving access to a bypass collection box with a damper which allows
one to vary the intake air. In terms as adjusting the vent for only what's
needed at different stages of firing. The side mounted damper would make it
much more flexible than the Orton seems to be (This woud require retrofitting
a damper to be added to the plenum to cover the holes. The damper would be
located under the kiln on most of the versions available.). The fumes are
vented using negative pressure in all the ducting. They claim it may be used
on kilns up to large as 34.5 cubic feet.

3- Skutt basically makes a direct copy of the Orton system. When I asked about
the suitability in my application I was told "We don't really know, call Dale
Fronk at Orton".



So far, I am seeing the L&L the most likely candidate to do the job. When I
called they said that they really can't guarentee that it will work.
"Sometimes if people find it isn't enough they get a second one for that kiln"
(@ $375.00 a copy). This was **Not** the answer I was hoping for.

Is there anyone who has used either or both of these systems on a kiln with
**paraffin** used as a resist? Please tell me your experience with these vents
and any advantages or disadvantages I may have missed. The Orton and the L&L
are comparably priced. I don't want to waste money on overkill. What matters
most is the effectiveness of the vent with cost being a distant second.

I hope to order the vent soon. I will appreciate any insight you can offer.


Regards,
Don Kopyscinski
Bear Hills Pottery
5 Lori Lynne Circle
Newtown, CT 06470
E-mail address:DonKopy@aol.com

KLeSueur on fri 16 jan 98

In a message dated 1/15/98 1:58:43 PM, you wrote:

<>

Several years ago I added on to my studio and brought my cone 10 reduction
kiln inside. I needed to vent it and asked my favorite hardware store guy if
he knew anyone who could build me a hood. He did. The guy, Jim Hall, built me
a 8'x8' hood of galvanized metal to go over my kiln, advised me about the
exhaust fan to use, and made an adaption to make it draw more efficiently. The
craftsmenship was excellent and it's held up through 5 years of very heavy
firing. I've been very happy with it. Jim used to work for the University of
Michigan fabricating heating and cooling systems, many into old buildings that
had to be retrofitted in a way that didn't disturb the "historic" look.

I don't know if he'd be willing but think it's worth a call. If you do any
fairs in Michigan you could arrange to pick it up when you come out or prevail
upon some other Ct. artist to bring it back for you.

JIm Hall
222 S. Lima Center Rd.
Chelsea, MI 48118
(313) 475-9225


Good luck,

Kathi LeSueur Ann Arbor, MI