mtigges@NOSPAM.SHAW.CA on tue 22 nov 05
On Tue, Nov 22, 2005 at 10:06:00PM -0600, Vince Pitelka wrote:
> >Our local guru doesn't like the idea of the envirovent. But I do. The
> >reason I like it is that the alternative really takes up too much
> >space. I have a very small work space.
>
> Goodness, what DOES your local guru like? I hope she/he is not a supporter
> of those round hoods that hang in the air directly above the kiln. They are
> almost completely useless, because the modest level of heat radiating from
> the outside of the kiln is not enough to create sufficient convection
> currents to carry fumes up to the hood. And the slightest air current or
> movement in the room carries the fumes farther away from the hood.
>
He likes small enclosed spaces for the kiln which are vented. His
reasons are two-fold; first he doesn't like the idea of drilling holes
in a kiln, second he likes an enclosed space of cinder blocks, just in
case. I certainly can't argue with number two. The only problem I
have with drilling holes in my kiln re the enviro-vent is the affect
on performance.
Mark
mtigges@NOSPAM.SHAW.CA on tue 22 nov 05
Since my kiln is in my work area, and I don't like working in the
winter with the doors open, brrr, I'm considering venting my kiln.
Our local guru doesn't like the idea of the envirovent. But I do. The
reason I like it is that the alternative really takes up too much
space. I have a very small work space.
My question is that my current kiln is actually a cone 1 kiln - I fire
to cone 6 (disclaimer, this is not inherently unsafe, it is only a
matter of the thickness of insulation with my kiln, the elements and
wiring are all identical). Will the kiln be able to still reach cone
6 with an envirovent added? My intuition suggests that sucking in
cold air will reduce the capabilities of the kiln at least somewhat.
My long term plan is to replace this kiln, but I'm unsure when I'll be
able to do it, so in the short term I am stuck with this one.
So, will I still be able to reach the same temps I do now, and at the
same rate? Or how drastically will the envirovent affect performance?
Thanks,
Mark.
William Melstrom on tue 22 nov 05
Mark, IMHO your local guru is wrong, kiln vents work great, and have an
extremely minimal effect on kiln performance.
It is really easy to make your own vent for about $50. I started an article
on the subject that I never finished, but take a look:
http://www.handspiral.com/kiln_vent.htm
It will help a lot if you can take a look at someone's installed commercial
system, so that you can get an idea of where and how many ventilation holes
you need to drill into the kiln. Don't get all hung up on this part -- you
can always plug holes or drill more.
good luck,
William Melstrom
www.handspiral.com
Vince Pitelka on tue 22 nov 05
> Our local guru doesn't like the idea of the envirovent. But I do. The
> reason I like it is that the alternative really takes up too much
> space. I have a very small work space.
Goodness, what DOES your local guru like? I hope she/he is not a supporter
of those round hoods that hang in the air directly above the kiln. They are
almost completely useless, because the modest level of heat radiating from
the outside of the kiln is not enough to create sufficient convection
currents to carry fumes up to the hood. And the slightest air current or
movement in the room carries the fumes farther away from the hood.
Aside from very expensive industrial quality ventillation systems, the
downdraft vents like the EnviroVent seem to be the only ones that DO work.
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
Gordon Ward on wed 23 nov 05
Hi Mark,
There is an added benefit to a direct draft system. The slight
negative pressure will suck the caustic gasses out of the kiln, thus
extending the life of the working components and controls.
Gordon
On Nov 22, 2005, at 10:16 PM, mtigges@NOSPAM.SHAW.CA wrote:
> On Tue, Nov 22, 2005 at 10:06:00PM -0600, Vince Pitelka wrote:
>>> Our local guru doesn't like the idea of the envirovent. But I do.
>>> The
>>> reason I like it is that the alternative really takes up too much
>>> space. I have a very small work space.
>>
>> Goodness, what DOES your local guru like? I hope she/he is not a
>> supporter
>> of those round hoods that hang in the air directly above the kiln.
>> They are
>> almost completely useless, because the modest level of heat radiating
>> from
>> the outside of the kiln is not enough to create sufficient convection
>> currents to carry fumes up to the hood. And the slightest air
>> current or
>> movement in the room carries the fumes farther away from the hood.
>>
>
> He likes small enclosed spaces for the kiln which are vented. His
> reasons are two-fold; first he doesn't like the idea of drilling holes
> in a kiln, second he likes an enclosed space of cinder blocks, just in
> case. I certainly can't argue with number two. The only problem I
> have with drilling holes in my kiln re the enviro-vent is the affect
> on performance.
>
> Mark
>
> _______________________________________________________________________
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>
Arnold Howard on wed 23 nov 05
From:
Will the kiln be able to still reach cone
> 6 with an envirovent added? My intuition suggests that sucking in
> cold air will reduce the capabilities of the kiln at least somewhat.
> So, will I still be able to reach the same temps I do now, and at the
> same rate? Or how drastically will the envirovent affect performance?
According to Orton, a downdraft kiln vent increases firing time by about
five minutes for firings up to cone 4; 12 minutes for firings from cone 4 to
10. It has little effect on maximum temperature.
From the shut-off temperature down to 1000 deg. F, the vent has little
effect on cooling time. From 1000 deg. F to room temperature, a vent reduces
cooling time by about two hours.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
William & Susan Schran User on wed 23 nov 05
On 11/22/05 8:18 PM, "mtigges@NOSPAM.SHAW.CA"
wrote:
> My question is that my current kiln is actually a cone 1 kiln - I fire
> to cone 6 (disclaimer, this is not inherently unsafe, it is only a
> matter of the thickness of insulation with my kiln, the elements and
> wiring are all identical). Will the kiln be able to still reach cone
> 6 with an envirovent added? My intuition suggests that sucking in
> cold air will reduce the capabilities of the kiln at least somewhat.
>
> My long term plan is to replace this kiln, but I'm unsure when I'll be
> able to do it, so in the short term I am stuck with this one.
Since I proclaimed some time back that my vent system resulted in even
firing temperatures with a fast firing, I did a firing without the vent. The
vent does indeed provide me with very even firing temps top to bottom.
I looked at the EnviroVent on the Skutt website. IMHO, I would not recommend
any vent system that has the motor mounted on the bottom of the kiln. Too
much heat and possible vibration issues. I would recommend a downdraft vent
system that has the motor mounted away from the kiln, and I would recommend
metal duct work (flexible or rigid) with all seams sealed with metal duct
tape. I would further suggest the motor be mounted on the wall or window
opening such that there is no duct work coming out of the exhaust side of
the motor, so there is no chance of venting fumes back into the room.
At home I use a Bailey vent system that is attached to the bottom wall
section of the kiln. The duct leads to the motor that's attached to a piece
of plywood that fits into a close window opening. I just open the window,
insert vent and close window on the plywood. For this system, the top spy
hole plug is left out while running.
At school we use the L&L Ventsure system. A metal box attaches to the kiln
stand and metal duct work attaches to the box (the box can also be mounted
on the side of the kiln). Holes are drilled through the kiln floor, the
number depending on size of kiln. There is a opening on the box that has a
sliding cover, so the amount of draft can be adjusted. The motor is attached
to the wall, venting directly outside. For the L&L system, no other holes or
openings are used. They state there's enough leakage between sections and
between lid and wall, to supply make-up air.
Regarding your kiln, if you're handy, and your kiln is a sectional, perhaps
you can remove the stainless steel skin, add a layer of fiber blanket, and
reattach the metal skin, with adjustments for added diameter.
-- William "Bill" Schran
Fredericksburg, Virginia
wschran@cox.net
wschran@nvcc.edu
William & Susan Schran User on wed 23 nov 05
On 11/23/05 1:16 AM, "mtigges@NOSPAM.SHAW.CA"
wrote:
> The only problem I
> have with drilling holes in my kiln re the enviro-vent is the affect
> on performance.
Probable negative affect, negligible. Positive affect, definitely, as long
as the vent is running.
-- William "Bill" Schran
Fredericksburg, Virginia
wschran@cox.net
wschran@nvcc.edu
Gordon Ward on wed 23 nov 05
Orton has dropped their under kiln models. Orton's new Vent Master
uses a non-corroding tube from the bottom of the kiln to the blower (
it can mount on the wall or sit on the floor), which is a big
improvement over aluminium ducting. This allows you to have easy
access to the venting from the blower going outside if it ever needs
replacing. The Bailey system uses aluminium ducting from the bottom of
the kiln to the blower, which is a pain to replace (and it will need
periodic replacing) Use only solid aluminium, not the stretchy stuff
like Bailey includes with their system. The stretchy aluminium ducting
has a very limited life in this type of application.
On Nov 23, 2005, at 6:47 AM, William & Susan Schran User wrote:
> IMHO, I would not recommend
> any vent system that has the motor mounted on the bottom of the kiln.
mtigges@NOSPAM.SHAW.CA on wed 23 nov 05
On Wed, Nov 23, 2005 at 09:47:41AM -0500, William & Susan Schran User wrote:
> On 11/22/05 8:18 PM, "mtigges@NOSPAM.SHAW.CA"
> wrote:
>
> > My question is that my current kiln is actually a cone 1 kiln - I fire
> > to cone 6 (disclaimer, this is not inherently unsafe, it is only a
> > matter of the thickness of insulation with my kiln, the elements and
> > wiring are all identical). Will the kiln be able to still reach cone
> > 6 with an envirovent added? My intuition suggests that sucking in
> > cold air will reduce the capabilities of the kiln at least somewhat.
>
> I looked at the EnviroVent on the Skutt website. IMHO, I would not recommend
> any vent system that has the motor mounted on the bottom of the kiln. Too
> much heat and possible vibration issues. I would recommend a downdraft vent
> system that has the motor mounted away from the kiln, and I would recommend
> metal duct work (flexible or rigid) with all seams sealed with metal duct
> tape. I would further suggest the motor be mounted on the wall or window
> opening such that there is no duct work coming out of the exhaust side of
> the motor, so there is no chance of venting fumes back into the room.
I agree with this. I don't like the idea of inducing vibrations on
the kiln.
When I originally started thinking about this I did not know how much
these things cost. I can afford it, but I don't like be taken to the
cleaners. US$400+ IMO is kind of pricey. I understand licensing,
liability and the small size of the market, but really, that's a
pretty expensive proposition.
So, I am pretty handy. I see few reasons why I shouldn't put the
system together myself.
The immediate question is what kind of squirrel cage to get. I see on
the L&L site that theirs pulls 130 CFM through 3" pipe, and they claim
that is sufficient for 20 CF of kiln. Ok. That's a pretty cheap
motor/cage. Second question though is ... heat. I would be worried
about the ball bearings / grease getting too hot leading to a possible
catastrophe.
I see on Skutt's FAQ they claim the vented gasses don't reach higher
than 150F. I have a pretty hard time believing that intuitively. Has
anybody measured this? Do the commercial versions use brass bearings?
Are they loud?
Has anybody built their own? Or detailed info about the specs of
these units?
> Regarding your kiln, if you're handy, and your kiln is a sectional, perhaps
> you can remove the stainless steel skin, add a layer of fiber blanket, and
> reattach the metal skin, with adjustments for added diameter.
I have thought about this. But ultimately it is too small and a bit
worn down to boot, so replacement is quite called for. I draws less
than 30 amps, and I have a limit of about 45 amps (60 amp breaker), so
I will be getting a bit bigger kiln sometime.
Mark.
William Melstrom on wed 23 nov 05
> Has anybody built their own? Or detailed info about the specs of
> these units?
Mark, did you miss my message? Here is the gist of what I wrote:
It is really easy to make your own kiln vent for about $50. I started an
article
on the subject that I never finished, but take a look:
http://www.handspiral.com/kiln_vent.htm
It will help a lot if you can take a look at someone's installed commercial
system, so that you can get an idea of where and how many ventilation holes
you need to drill into the kiln. Don't get all hung up on this part -- you
can always plug holes or drill more. The same goes for the "diffuser box."
You can plug holes or drill more into the diffuser.
This Is Not Rocket Science, anyone can do it.
good luck,
William Melstrom
www.handspiral.com
Jeremy/Bonnie Hellman on wed 23 nov 05
I didn't measure it scientifically, but the Envirovent's metal tube that
leads the exhaust gasses away from the kiln does not get hot enough to melt
plastic and at bisque temps the air coming out did not burn my hand. I
didn't test it at a ^6 firing.
Bonnie
----- Original Message -----
From:
To:
Sent: Wednesday, November 23, 2005 11:58 AM
Subject: Re: enviro-vent addition
> On Wed, Nov 23, 2005 at 09:47:41AM -0500, William & Susan Schran User
> wrote:
>> On 11/22/05 8:18 PM, "mtigges@NOSPAM.SHAW.CA"
>> wrote:
>>
>> > My question is that my current kiln is actually a cone 1 kiln - I fire
>> > to cone 6 (disclaimer, this is not inherently unsafe, it is only a
>> > matter of the thickness of insulation with my kiln, the elements and
>> > wiring are all identical). Will the kiln be able to still reach cone
>> > 6 with an envirovent added? My intuition suggests that sucking in
>> > cold air will reduce the capabilities of the kiln at least somewhat.
>>
>> I looked at the EnviroVent on the Skutt website. IMHO, I would not
>> recommend
>> any vent system that has the motor mounted on the bottom of the kiln. Too
>> much heat and possible vibration issues. I would recommend a downdraft
>> vent
>> system that has the motor mounted away from the kiln, and I would
>> recommend
>> metal duct work (flexible or rigid) with all seams sealed with metal duct
>> tape. I would further suggest the motor be mounted on the wall or window
>> opening such that there is no duct work coming out of the exhaust side of
>> the motor, so there is no chance of venting fumes back into the room.
>
> I agree with this. I don't like the idea of inducing vibrations on
> the kiln.
>
> When I originally started thinking about this I did not know how much
> these things cost. I can afford it, but I don't like be taken to the
> cleaners. US$400+ IMO is kind of pricey. I understand licensing,
> liability and the small size of the market, but really, that's a
> pretty expensive proposition.
>
> So, I am pretty handy. I see few reasons why I shouldn't put the
> system together myself.
>
> The immediate question is what kind of squirrel cage to get. I see on
> the L&L site that theirs pulls 130 CFM through 3" pipe, and they claim
> that is sufficient for 20 CF of kiln. Ok. That's a pretty cheap
> motor/cage. Second question though is ... heat. I would be worried
> about the ball bearings / grease getting too hot leading to a possible
> catastrophe.
>
> I see on Skutt's FAQ they claim the vented gasses don't reach higher
> than 150F. I have a pretty hard time believing that intuitively. Has
> anybody measured this? Do the commercial versions use brass bearings?
> Are they loud?
>
> Has anybody built their own? Or detailed info about the specs of
> these units?
>
>> Regarding your kiln, if you're handy, and your kiln is a sectional,
>> perhaps
>> you can remove the stainless steel skin, add a layer of fiber blanket,
>> and
>> reattach the metal skin, with adjustments for added diameter.
>
> I have thought about this. But ultimately it is too small and a bit
> worn down to boot, so replacement is quite called for. I draws less
> than 30 amps, and I have a limit of about 45 amps (60 amp breaker), so
> I will be getting a bit bigger kiln sometime.
>
> Mark.
>
> ______________________________________________________________________________
> 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.
Michael Wendt on wed 23 nov 05
Mark,
A 50 cfm fan from the Surplus Center would be more than adequate. The holes
for venting are very tiny and the rule with all vacuum systems is: once you
pull a certain level of vacuum, atmospheric pressure is all you have to
force air into the kiln through the tiny holes.
Also, I shut the vent fan off about an hour before I expect the cones to
fall because the vent also pulls cold air into the kiln sitter and chills
the cones so much the kiln actually overfires by quite a bit if left to the
sitter.
Total cost to build your own should be around $50-60.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, Idaho 83501
USA
wendtpot@lewiston.com
www.wendtpottery.com
Arnold Howard on wed 23 nov 05
From:
> I see on Skutt's FAQ they claim the vented gasses don't reach higher
> than 150F. I have a pretty hard time believing that intuitively. Has
> anybody measured this?
It is counter-intuitive but true. Orton, too, states that their downdraft
kiln vent reaches 100 - 155 deg. F inside the duct.
Duct temperature remains low because only a small amount of air is removed
from the kiln and then mixed with a large amount of room-temperature air.
Downdraft vents are expensive because the components cost so much.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com
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