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-   -   Attaching Flex duct to register boot (http://www.diychatroom.com/f17/attaching-flex-duct-register-boot-33067/)

avshockey 12-02-2008 11:55 PM

Attaching Flex duct to register boot
 
I am running a 5 inch duct run using flex duct (type F090) to a register boot. My question is, since the flex duct is the same diameter as the register boot, how to a fit the flex over the register boot? Do I crimp the register boot so the flex will fit over it or do I need a coupler?

hvaclover 12-03-2008 12:13 AM

What is the reason for so small a diameter flex?

beenthere 12-03-2008 12:17 AM

It slides over.
Takes a little practice.

Daltex 12-03-2008 02:26 PM

Don't forget to prelube with mastic and use a tie strap over the liner then the insulation jacket.

hvaclover 12-03-2008 03:26 PM

Hey deltex why mastic?

I freely admit that I use all rigid pipe and very little flex.

I would pull back the outer insulation, push the flex on the fitting, zip tie that, and then push the insulation over the flex duct and fitting and duct tape with approved tape.


What am i missing on mastic?

bluefitness 12-03-2008 04:17 PM

Quote:

Originally Posted by hvaclover (Post 193310)
Hey deltex why mastic?

I freely admit that I use all rigid pipe and very little flex.

I would pull back the outer insulation, push the flex on the fitting, zip tie that, and then push the insulation over the flex duct and fitting and duct tape with approved tape.


What am i missing on mastic?

You should tape the flex (plastic liner) to the boot after putting on the panduit strap. Then you pull the insulation over that and tape the exterior liner to the boot as well.

avshockey 12-03-2008 04:19 PM

It is uninsulated because it is in a conditioned area. The flex definately does not fit the "torpedo" stile register boot. I called the HVAC place were I purchase it and he said the I would have to crimp the register boot to get it to fit. Would crimping the register boot disrupt the air flow bad enough that this would not be advised. Do they make register boots that have a male end to attach flex to?

hvaclover 12-03-2008 04:37 PM

Quote:

Originally Posted by bluefitness (Post 193327)
You should tape the flex (plastic liner) to the boot after putting on the panduit strap. Then you pull the insulation over that and tape the exterior liner to the boot as well.

Heh, I just read the instruction. I don't do enough flex to claim any real expertise in whole system design. But we do kinda specialize in (that is to say each job we've done has been a success) in correcting badly heated home additions.

biggles 12-03-2008 05:54 PM

take a niddle nose pliers and grab the end of the duct about 2" down 1/4 turn the edge all the way around and that will narrow it down to accept the 5" now to attatch it....wrap the end with one full around lenght of duct tape.slip the flex on ,and again the full around duct tape then zip screw it into the duct.if it was insulated you then would pull the insulation over the screws and duct tape that.....the key word here is DUCT TAPE:wink:.....2 pieces of duct tape aren't coming apart.

hvaclover 12-03-2008 06:05 PM

Quote:

Originally Posted by biggles (Post 193379)
take a niddle nose pliers and grab the end of the duct about 2" down 1/4 turn the edge all the way around and that will narrow it down to accept the 5" now to attatch it....wrap the end with one full around lenght of duct tape.slip the flex on ,and again the full around duct tape then zip screw it into the duct.if it was insulated you then would pull the insulation over the screws and duct tape that.....the key word here is DUCT TAPE:wink:.....2 pieces of duct tape aren't coming apart.

SCREWS?:huh:

Not criticizing, but wouldn't you worry about the flex ripping? I know you used duct tape but I have seen it come loose over the years and the screws rip loose.

Just asking, like I said flex is not my specialty.

Daltex 12-03-2008 06:07 PM

Quote:

Originally Posted by hvaclover (Post 193310)
Hey deltex why mastic?

I freely admit that I use all rigid pipe and very little flex.

I would pull back the outer insulation, push the flex on the fitting, zip tie that, and then push the insulation over the flex duct and fitting and duct tape with approved tape.


What am i missing on mastic?

I may be overdoing it but flex is known to get kicked around and pulled on after installation. The weakest link is the connectors at the take offs and jack boots. The mastic glues it solid so you don't have to rely on the zip alone to hold it. I just zip the insulation and now you have me thinking about taping that for more support.

The mastic also really does lubricate it to make slipping it over the fitting easier and it holds it in place while zipping it tight.

hvaclover 12-03-2008 06:09 PM

Quote:

Originally Posted by Daltex (Post 193388)
I may be overdoing it but flex is known to get kicked around and pulled on after installation. The weakest link is the connectors at the take offs and jack boots. The mastic glues it solid so you don't have to rely on the zip alone to hold it. I just zip the insulation and now you have me thinking about taping that for more support.

The mastic also really does lubricate it to make slipping it over the fitting easier and it holds it in place while zipping it tight.

Well good, then we helped each other out. Mastic it is. Good idea and a very sensible explanation:thumbsup:

beenthere 12-03-2008 06:10 PM

Technically, all joints are supposed to be sealed with mastic compound or mastic tape.

hvaclover 12-03-2008 06:17 PM

Hey, there's that echo again:laughing:

bluefitness 12-03-2008 08:31 PM

Use this to crimp it:

http://www.lowes.com/lowes/lkn?actio...5198-273-HC5VS


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