The Down Draft Vent
The down draft vent system is positioned under a top-loading kiln and usually on the back wall of a front-loading kiln. The vent removes fumes through small holes drilled into the firebricks. There are several brands of vents available. An example is the Orton KilnVent.
If you fire a top-loading kiln with the Orton KilnVent turned off or removed for repair, cover the air exit holes in the kiln bottom. An easy way to do this is to place a kiln shelf over the holes.
Leave the vent on throughout the kiln firing and cooling cycle. Turn the vent off when the kiln is cool enough to unload bare-handed. The vent will help remove moisture during “candling” at the beginning of the firing. The moisture inside the duct and motor will dry out as the kiln heats.
When using the vent, leave the kiln’s peephole plugs in place and lid down all the way throughout the firing. The vent operates under negative pressure, which requires that the lid and peepholes be closed.
When the aluminum duct begins to deteriorate, small holes will appear and you will begin to smell kiln fumes. At that point, replace the duct rather than attempt to repair with duct tape.
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