A designated number of holes are drilled in the lid and floor of the kiln either in the factory or on location. A spring loaded plenum cup is placed under the kiln and tensioned between the floor of the kiln and the floor under the kiln. The holes in the floor of the kiln are drilled in a tight pattern so the plenum cup can cover them all. The other end of the cup is connected by 3” ducting to a fan which is generally mounted on the wall. On the opposite end of the fan the air is ducted through the wall to the outside air. The plenum cup has 3 additional holes from which it draws room temperature air to mix with the heated air from the kiln. This serves 2 purposes. Since the kiln air is mixed with cooler room air the air coming out of the end of the vent is never hotter than an average hair dryer. Secondly, the holes in the plenum cup are sized to reduce the vacuum on the kiln chamber so only a small amount of air is moving through the kiln. This ensures the firing time is not affected and the ware is not at risk. Using gloves to protect your hands, stretch the flex tubing to the proper length for your installation. Stretch out the last 3” of tubing on each end of the duct to ensure they are wide enough to fit over their connections. Be careful not to collapse the open end of the fl ex tubing. You should be able to stretch the flex tubing 6 ft. to 8 ft. Attach the length of 3” diameter aluminum flex tubing to the 3” sleeve on the plenum cup and secure with the hose clamp. Place the spring over the plenum cup stand post and insert the 7/16” stand post into the small hole in the bottom of the aluminum plenum cup. Refer to the installation drawing if necessary. When properly assembled the plenum stand should be spring loaded into the bottom of the plenum cup. Place the plenum cup and stand under the holes drilled in the kiln floor by rotating the cup horizontally, compressing the spring to permit cup rotation to vertical and releasing the spring tension. Ensure that the plenum cup is centered under the holes in the kiln’s floor.
