Robert Friedman on fri 25 feb 00
I am interestested in putting an active venting system on my electric
kilns. I believe that the sytems commercially available are far to
expensive for the technology which seems pretty simple.
Does anyone have a design or guidelines to follow in hooking up my kilns?
One is about 4 cu. ft. and the other is about 7 cu. ft.. Both have a vent
hood with an active system attached but it is too high above the kilns to be
totally effective. If you are wondering why I want more venting, it is also
because of combustion by-products fouling the pivot point on my kiln sitter
in under one year despite lid propping until red heat.
Jim Cullen on sat 26 feb 00
Robert,
my first question is...What the Hell are you firing that has that much
by-product? Most of the clays I've run across recently have been cleaned up
and don't have all those nasty things that clay used to have, namely sulfur.
But, your question about the cost of kiln vents is exactly the same way I
felt. So, like you, I decided to build my own.
I first shopped for an exhaust motor that would give me enough draw without
sucking my pots down the hose. I settled on 60 CFM. That works fine. I'm
moving the air about 5 feet from the bottom of my kiln to the motor which is
attached to the wall where it exits the room. On the outside I placed a
standard dryer vent with a flapper door the is opened by the exhausting air.
I cover the vent opening with screen material to prevent critters from
opening the flap and entering. For vent hose I used aluminum dryer hose and
measured the temperature at the entry point to the motor at 108 degrees. This
is cooler than toast. You can hold your hand against it. For the bottom vent
I purchased a sheet metal panel about 24 inches square and cut a hole in the
middle and mounted a 4 inch elbow which extends beneath my kiln. I drilled to
3/8th inch holes in the center of the floor of the kiln and two in the center
of the lid each about 2 inches apart. I'm not using the vent for exhausting
fumes as much as I am for evening the overall temperature and a more constant
firing. I motor I purchased from Grainger.com. It was stock number
4C440-760CFM Blower @ $46.12 with tax. Some of the parts I had laying around
so I guess the whole thing may have cost me $60 out-of-pocket. Of course with
my labor the total probably came to around $3,000 but since I don't pay
myself, it was a good deal.
I can't believe that a $300 vent would serve me any better and if mine burns
out in a year I'll buy another motor and still be ahead.
Sorry, no drawings, I sort of winged it as I went along.
Good luck
KEEP CENTERED and WELL VENTILATED
Cullen
Naperville, Illinois
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