vince pitelka on fri 1 dec 00
> I wouldn't, naturally aspirated are far more controllable. in my
> experience blowers are all or nothing at all!
> >Now looking forward to getting power burners one of these days. Veronica
This is a bit misleading. Veronica, like many people, has apparently found
that power burners are easier to control. I still prefer natural draft
kilns, tube burners, and venturi burners, and I love a kiln that is not
hooked up to the power grid. But power burners are very easy to control as
long as there is an adjustable shutter on the blower intake. People tend to
put too much faith in those cheesy speed-control rheostats that come on some
power burners, and that is a mistake. They should not even be an option.
We have a 50 cubic foot downdraft with power burners. We turn the
rheostats on high to get the blowers jump-started, and then when we light
the burners we turn the rheostats down to medium, and they stay there for
the entire firing. We do all the air adjustments with the intake shutters
on the blowers. It gives very sensitive adjustment.
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Jonathan Kaplan on sat 2 dec 00
>> I wouldn't, naturally aspirated are far more controllable. in my
>> experience blowers are all or nothing at all!
>> >Now looking forward to getting power burners one of these days. Veronica
But power burners are very easy to control as
>long as there is an adjustable shutter on the blower intake. People tend to
>put too much faith in those cheesy speed-control rheostats that come on some
>power burners, and that is a mistake. They should not even be an option.
Vince is quite correct here, and it should benoted that the electronics to
control the speed of an AC motor are more then cheesey, they are really not
reliable and do not produce a smooth electrical signal to the blower. Thats
why you see the typical Graingers squirel cage blowers with the added flaps
over the blower intakes. Both these methods are cheap, inexpensive, and
often used, but are really poor substitutes for the correct solutions. The
flap idea is really an inaccurate method.
In addition, so are the typical gas valves that are used. These "gas cocks"
so to speak as they are referred to in the trade are designed to either be
ON or OFF. Adjustments in between these two parameters are inexact and do
not provide preceise meterin of the gas, just as the blower arrangements
with the flap and the rheostat do not provide precise metering of the air.
So here's what to do.
Don't be cheap. Spend some of your hard earned money or cash that you took
off the top from your Holiday sales or recent craft festival and buy a
limiting orfice valve for each burner which will precisely meter the gas,
and a manual butterfly shutter valve for each blower. This will allow the
blower to run at full speed and all you do is physically limit the amount
of air exiting the blower. Most typical forced air blowers that potters use
are based on a 2" diameter pipe. Get a 2" butterfly/shutter valve.
The gas is either 1/2" or 3/4". Get the same diameter limiting orfice
valve. Its not rocket science and you can do the retrofit yourself. You
keep the gas cock in place and add the limiting orfice valve after the gas
These parts are available from North American Combustion in Cleveland. We
are retrofitting a colleagues kiln in Denver and for 2 limiting orfice
valves and 2 manual butterfly/shutter valves and shipping, the cost was
Shouldn't you spend some extra time and money to make sure you have
reliable firings that provide consistency and less aggrevation?
I'll have a schematic drawing soon with part numbers. So if you wanna see
how it is done, send me a SASE (self addressed stamped envelope). I'll get
the drawings to you in about 2-3 weeks or so.
Jonathan Kaplan, president
Ceramic Design Group
PO Box 775112
Steamboat Springs CO 80477
voice and fax 970 879-9139
1280 13th Street Unit 13
Steamboat Springs CO 80487
(please use this address for all deliveries via UPS, comman carrier, FEd
Cobus Potgieter on sat 2 dec 00
Can you maybe scan and e-mail these plans?
----- Original Message -----
From: "Jonathan Kaplan"
Sent: Saturday, December 02, 2000 5:04 PM
Subject: Re: low BTUs - power burners vs. natural draft
> I'll have a schematic drawing soon with part numbers. So if you wanna see
> how it is done, send me a SASE (self addressed stamped envelope). I'll get
> the drawings to you in about 2-3 weeks or so.
> Jonathan Kaplan, president
> Ceramic Design Group
> PO Box 775112
> Steamboat Springs CO 80477
> voice and fax 970 879-9139
> Plant Location:
> 1280 13th Street Unit 13
> Steamboat Springs CO 80487
> (please use this address for all deliveries via UPS, comman carrier, FEd
> Ex, etc.)
> Send postings to email@example.com
> 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
Jonathan Kaplan on sat 2 dec 00
>Can you maybe scan and e-mail these plans?
I am not fully up to speed in cybergear. I don't have a scanner yet. I'll
see who has one in town and see if they can help me out. I haven't drawn
the plans yet. They will be done in about 2 weeks or so.
They will be draawn in a program called "Vellum". If you have this
application I can send it as an attatchment
Ceramic Design GroupLTD/Production Services
PO Box 775112
Steamboat Springs, CO 80477
(970) 879-9139 voice and fax
UPS: 1280 13th St. Unit13
Steamboat Springs, CO 80487