Take the 2-minute tour ×
Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. It's 100% free, no registration required.

I have been doing some basic HVAC duct work as part of a remodeling project and I can never get the pieces to fit together without massive amounts of elbow grease and mangling the ends. Is there some kind of trick that I am missing that makes it easier? I am working with 6 inch, and 7 inch sheet metal duct and vent boots as well as some flex duct.

share|improve this question

2 Answers 2

up vote 8 down vote accepted

You need a duct crimper like this to reduce the diameter of the end of one piece of duct:

enter image description here

Run the tool around the end of the duct so that you have multiple parallel crimps. That piece should slide right into the uncrimped piece, giving you a secure connection to tape.

If you don't want to spring for a dedicated tool, I've seen where people use needle-nosed pliers to do the crimping.

share|improve this answer
2  
The reason this works is that the crimps, by folding part of the tube inward, shrink the effective radius and thus make it possible to slide the crimped end into the uncrimped one. (I've used the needle-nose trick on rain gutters.) –  keshlam Jun 8 at 23:56

If the ends are already crimped from the factory, get your duct pretty close to being in line, in other words one only slightly angled from the other. This will allow one portion of the crimped end to go no more than a 1/4" in until it begins to get difficult. Find a away to keep the duct stable (I usually straddle the duct to hold it steady) while you are trying to get the last edge past the other, it usually takes both hands to do, using your thumbs to push the last part of the crimped end in while you use, if you can picture this, the free fingers to help keep the uncrimped round or at least to keep it from deforming. The reason being where the metal gets caught on the mating piece, when you push down to tuck it in so to speak, the other piece will try to follow it down too. The free fingers will help govern this problem, but the thumbs do most of the pushing in to get the parts to line up. Then again you can you could use a crimper or needle nose pliers in a pinch...

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.