Duct connection method

[agmantoo]

I am wanting to install a package type heatpump using the round flexible type duct to the existing, in floor, duct work in a mobile home . I know that I will need a collar for the round duct but how do I fasten the collar to the existing flimsy mobile home duct?

[Cabin Fever]

What is the "flimsy mobile home duct" made of? Most ductwork is sheet metal and one uses sheet metal screws to fasten things like your collar. (Of course, you already know that!) So I'm thinking that sheet metal screws won't work for your project.

How about pop rivets?

[agmantoo]

"flimsy mobile home duct" is some type of foil as best I can determine! Real crap but standard for this application as I was told. I would think I would need to "sandwich" the mobile home duct between some type of collar and a backing plate of sorts. I have done some research but cannot find a solution. In the old system that I have removed, someone had attempted to tape the collar to the mobile home duct but it had come loose and fallen to the ground. I am trying to avoid this foulup with the new heatpump.

[caballoviejo]

I've got no help for you Agmantoo except to say I'd visually check out he types of duct fittings and tubes that are available at moble home suppliers. I'd try to come up with something close to looking like it would mate the two systems then I would modify it by whatever means after looking at it. Somewhere there might be a particular part designed for just what you want but these days nobody will know or even think unless they carry it and can make quick bucks out of it.

[Cabin Fever]

Could you use PVC or CPVC plumbing fittings of the of the correct diameter? "Stretch" the flexible ductwork over the fitting and then hold it in place with an adjustable hose clamp or cable ties?

[mtman]

you cant tie into the round duct you have to cut it then make a box out of what they call duct board then put 2 collors into the board tie in the one you cut and on the other one run the duct you want to run make shure you make the box big enough to have the 2 sizes yoy need

[Hip_Shot_Hanna]

cable ties come in all sizes and cheap !!!