Insert T in insulated flex duct ?

4 years ago

The fresh supply air for our sauna is 6" flex that runs from an outside wall cap across the ceiling of the sauna to a vent in the changing/shower room. I want to add a direct vent in to the sauna from this duct (and fortunately the flex goes over the correct spot for the vent) so I need to install a T in the flex.

I'd been taught years ago that the best way to do this is to cut the insulation and inner duct but not to cut the spiral wire itself as leaving it helps to hold everything together (but still use clamps).

I'm working in a really tight space and tried this but I'm having difficulty getting the inner duct properly on to the T.

I can cut the spiral wire but I'm not sure if that will help or not as I'm not sure I have enough room in the ceiling cavity to peel back the outer insulation enough to expose the inner duct.

Any advice on this appreciated.

The blue arrows show the approx path and airflow of the flex.

Featured Answer

klem1

4 years ago

Don't worry bout it,I think the origional idea was that wire would hold duct in place while working with one hand to install zip-ties. You do realize inner duct must be zip-tied then insulation pulled over it and taped or zip-tied ?

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Comments (8)

HU-867564120
4 years ago
Not cutting the wire would make the work unbearably difficult, IMO. I always cut the wire.
opaone thanked HU-867564120
klem1
4 years ago
Not cutting wire sound's like something that origionated with the two clowns called I Heard & They Said. Pay no attention,their pass time is confusing people and spreading bad ideas.
opaone thanked klem1
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opaone
Original Author
4 years ago
Thank you both. I think the idea behind not cutting the wire is that in a tight space where its difficult/impossible to reach behind the wire remaining connected helps to keep the flex in place.

I am finding this quite impossible though (and a reminder why I didn't become an HVAC person) :-)
opaone
Original Author
4 years ago
The back side is up against closed cell spray foam. It was sprayed after the duct went in so the duct is partially encased in the foam and I had to spend some time trying to pull it away and separate it which proved quite fun. :-)
opaone
Original Author
4 years ago
Yep. Using band clamps though as I've no idea where my panduit tool is.
klem1
4 years ago
It's much easier while working inside an attic, on your knees,amongest loose fill insulation and 20 years worth dust.
opaone thanked klem1
opaone
Original Author
4 years ago
:-)