Kevin Mark Klughart
PhD, PE, JD, MIP, LLM
Patent Attorney / Engineer
This project doesn't sound like much, but was quite involved. My wife and I recently purchased a new washer and dryer because our washer finally died after 25 years. The LG units were both nice, but the dryer was a very tight fit for our laundry room. As seen below, there isn't much clearance between the dryer and the outside wall (3 inches) and even less between the dryer and the sink (5/8 inch). The allowable clearance between the back of the dryer and the back wall was less than 4 inches, making the use of conventional flexible duct material impossible.
The solution was a custom piece of ductwork shown below. The left 4-inch pipe is a sliding fit into the exhaust of the dryer, while the right 4-inch duct pipe fits through the outside wall to the point of the external vent flapper. The square section of tubing to the left is 4x4 inches to permit maximum flow. The box on the right is approximately 2.5 inches thick, but has sufficient volume to permit 4-inch flow to the right exhaust duct. Note that before installation, the terminal edges of each 4-inch circular duct were beveled slightly to permit ease of installation into both the dryer exhaust port and the outside wall.
Another view of the system shows the 4x4 square back duct which fits into a small depression in the back of the dryer so that the total extension of the duct beyond the far reaches of the back of the dryer is only about two inches.
What may look odd is the intersection between the left input pipe and the 4x4 left-right square tube. This offset was necessary to permit the left-right square tube to fit into a recess in the back of the dryer...
The square tube and left square box were fabbed with a box-and-pan brake to form open boxes which were then TIG welded shut with an appropriate cover. Not shown here are two internal baffles to ensure that there is no buildup of lint in the system. One baffle is a curved piece of material at the right entrance to the square tube, and the other baffle is located at the bottom of the square box from the entrance of the square tube to the lower edge of the output exhaust pipe.
A picture of the unit installed shows how little margin for error this system had for installation. While it would have been preferable to have more room to use conventional ducting, this system lived within the constraints without any wall demolition work or other modifications to the structure. Air flow is unimpeded and the 16-gauge aluminum construction guarantees a better structural venting system than obtainable with conventional ductwork.
The diagram below illustrates the placement of the dryer exhaust vent. Note that immediately to the left and below the dryer vent there is an indentation in the outer cover of the dryer. This is where the 4x4 vent tube is positioned to take advantage of this depression and minimize the amount of rear clearance needed to fit the dryer exhaust system.
One question you may have in implementing this system is whether the connection between the dryer and the input port to the exhaust system "leaks" since there is no clamp or other constraining element to ensure a tight fit. This issue is solved in two ways. First, the input exhaust tube extends over 10 inches into the dryer with a sliding fit. The fit is specifically designed to ensure minimal, if any, leakage. Next, by making the system out of aluminum the coefficient of expansion of the dryer exhaust is greater than the dryer exhaust duct. Thus, the exhaust system will expand slightly as warm air is pumped through the input tube, creating a tighter fit with the dryer exhaust vent. So far it seems to work great!
It should be note that the hardest part of this project was forming the cylindrical 4-inch aluminum tubes out of 16-gauge aluminum. These were formed by using a piece of angle iron and a large vice to curve the material after heating with a torch. Since I didn't have a slip-roll to form the material, this was the best that was possible at the time. The cut dimension of the aluminum was 11.75 inches to properly form a tube that would fit within existing 4-inch ductwork with a sliding fit. After formation, the curved piece was held together with a couple of large hose clamps, TIG welded together, heated, and beat over a large pipe to finish out the circular outline of the cylinder. More work than would have been necessary with the use of a slip-roll, but nonetheless effective.
Welding on this job was with 3/32-inch (and some 1/16-inch) Lincoln 4043 TIG rod, running anywhere from 75A to 125A depending on the weld seam in question.
One last note on the exhaust ducting for this dryer. While this LG unit does permit back/right/left/below ducting, none of the alternative ducting arrangements would have been acceptable for this situation. Even using the right ducting option, there was only 3-inches of clearance on the right side of the machine which would have made connecting the right duct to the exterior wall ducting impossible.
Kevin Mark Klughart
Registered Patent Attorney, USPTO
3825 Leisure Lane, Denton, TX 76210-5589
tel: 800-353-1211 / 940-320-0580 - fax 940-320-0581