Insulated Flex Duct Without Fiberglass
My standalone whole house dehumidifier is hard ducted for the most part.
The portion where the hard duct transitions to the dehumidifier is fiberglass insulated flex duct. The flex duct is needed to make the connection between the hard duct and the dehumidifier collar and to isolate the hard duct from the dehumidifier vibration. The insulation helps reduce the dehumidifier nose.
However, this short section of fiberglass insulated 8″ flex duct is what I have to handle if /when the dehumidifier needs to be replaced or removed for service. I want to get rid of the itchy fiberglass and replace it with something that does not require PPE to work with.
Is there any 8″ flexible insulated duct that does not have fiberglass?
If not, is there any product I can use for this transition that does not contain fiberglass or mineral wool?
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Replies
I googled and found this thread: https://hvac-talk.com/vbb/threads/114725-Any-non-fibreglass-duct-insulation-with-high-R-value
Which refers to EPDM-based AeroFlex products: https://aeroflexusa.com/aerocel-sheet-insulation-aeroflex-usa/
And closed-cell foam based ArmaFlex: https://www.armacell.us/products/aparmaflexaparmaflexfs-duct/
In both of these cases I am not seeing pre-insulated ductwork, so you may have to wrap the ducts yourself which is a big inconvenience. I don’t think the fiberglass insulation jacket is that big of an inconvenience. I usually just wear an N95 mask and gloves around it, and you’ll only need to mess with the very ends of it to connect/disconnect to your dehumidifier. I doubt that will happen very often. Fiberglass is a greener choice than either of those other two products I linked to as well. And I’m sure it’s one of the best values in terms of dollars per R-value.
The old school way to make a flexible joint in ductwork is a canvas joint about 1 to 4 inches wide. Anyone with a sewing machine and 2 hose clamps could make a round joint.
I do not think you have any need for thermal insulation on a dehumidifier ductwork so you could suit up and remove and dispose of the fiberglass and the outer jacket and use the hose you have.
I think you have gone off the deep end if you really feel the need to don a hazmat suit to handle a tiny amount of fiberglass. Everyone is different and maybe you happen to be much more sensitive to fiberglass I am.
Walta
For your specific situation, what I would do is put about a 6" long collar of galvanized duct on the end of the flexible, that way you can disconnect the duct without disturbing the flexible. I would also wrap the ends of the flexible in foil duct tape to encapsulate the fiberglass.
To the broader question, I wish there were better options. I was just thinking yesterday that other places in the house it's against building science principles to use permeable insulation against a cold surface that doesn't dry to the exterior, but somehow it's OK with HVAC ducts.
I also don't like the fiberglass insulated flex because it's just so flimsy. It's often run in spaces where rodent infestation would go unnoticed for a long time, and it's very attractive to rodents and offers almost zero resistance to them.
Thank you for the replies!
@matthew25: I had found the same thread. Unfortunately I think applying either of those products to flex is going to be rather difficult.
I wish you were correct about about not needing to connect/disconnect my dehumid very often - I'm on my 3rd whole house dehumidifier in 20 months. The current one is being replaced under warranty but I still need to deal with the labor. I hope they just had a bad batch and this will be the last time for years, but who knows. The prospect of having to deal with the fiberglass flex is the thing I dread most of all of this...
@walta100 - I agree I do not need thermal insulation, and considered removing and disposing of the fiberglass insulation leaving only the flex, but I think I need the insulation as a sound dampener - when the ducts are not connected and the dehumidifier runs there is an extremely annoying hum. I presume most of that could still be heard with only the uninsulated flex, but who knows.
I'm not wearing a full hazmat suit, but I am very sensitive to fiberglass itch especially at my wrists. So in addition to an N95 mask, its pants tucked into socks, and gloves taped to a long sleeve shirt. Still got fiberglass itch for several days as a result of removing the gloves, which I think had some on them...
@DC_Contrarian: BRILLIANT IDEA!!! THANK YOU!!
I can put some thin neoprene tape on the tapered dehumidifier duct collar to prevent any vibration noise between the dehumid duct collar and the new collar, and that will also help seat the collar. If there is too much noise from the dehumi through that 6" piece, it will be easy to wrap the outside of that rigid 6" piece with sound deadening material. The added benefit is I think it will also make for an easier change out in the future. I hope I don't need to do this again, but who knows.