How to Adjust a Large Sheet Metal Duct Elbow
If you’re dealing with duct over 16″ in diameter, chances are you’ve had to employ an adjustable 90 degree sheet metal elbow; and if this is true, you’ve had the elbow get stuck on you and not been able to adjust it to your desired bend radius. You’re not alone! Even skilled installers deplore having to adjust large adjustable elbows. They can be time wasters if you don’t know a few tricks. I’ll spare you the embarrassment I had as an apprentice tasked with adjusting 24 elbows between 18 inches in diameter and 24″ in diameter my first week on the job.
- Put on some gloves. The gloves are going to help with grip, and protect you from cutting your arm off.
- Although not acceptable on job sites, I like to wear shorts. You often must straddle the elbow and hold one gore with your legs while turning others with your hands. Sometimes it’s all about becoming one with the fitting.
- Examine the gores (in case you’re wondering a gore is each section of the adjustable elbow). The gores are made to slide within one another. When these get off track, you can’t adjust the elbow.
- If you’re working with spiral duct, I like to go ahead and attach one end of the elbow onto the spiral duct and use the spiral to hold the elbow as I adjust it. Even if the spiral is in the air and I have to work off of a ladder, I find it easier to turn a stubborn elbow with the spiral duct holding one end.
- Conceptually, when the seam is completely lined up your elbow is 180 degrees. When the seam alternates to opposite sides every other gore you are at 90 degrees.
- “The Drop” – Pick the elbow up to about stomach height and drop it on end. You want the entire end of the elbow to hit the ground at the same time so as not to get dings. This drop will sometimes loosen the part that is stuck.
- “The Roll” – Set the elbow on end and look for any flat sides. Then flip the elbow ends out and roll it gently on flat ground to “roll out” any flat spots. Put a little pressure into your roll, but pushing too hard will bust the elbow completely in half.
- The “Straddle and Screech” – Wearing your best gloves, and bear legged, lay the elbow down flat on the ground with one end pointing behind you, and the before you. Trap one gore between your legs and use your hands to turn as hard as you can. It helps to make a loud “ahhhhhhh” sound. Remember you want to turn the elbow, not squash it down. The more oval you make the elbow, the harder it is to turn.
- The “Surgeon” – Get the elbow up on an examining table and get your nose about an inch away from the gores. Follow each gore with your eyes, inside the elbow and out, and identify where the stuck point is. Once found, use a sheet metal hammer and flat screwdriver to realign.
Please feel free to leave your own tips and tricks below. Spare me the safety rhetoric. I know I should be wearing boots, safety glasses and probably a high visibility vest in these photos.