RV style AC attic duct work - what is it called, brand etc

Hi Everyone,

Thanks for your input. It all helps.

A few thoughts, it appears I may have to make up the new ducting, which is not a real problem, I can do this. The issue now is to finding the foam board or duct board in 1/4" and foil outside warped. Not sure if Jayco will sell it direct, it's an option if I can't find the board.

I did find this which could work, but I'm not sure of the thickness, yet. I have to call them, Thermopan, by the connector strips they sell, it appears it might be more like 1/8". https://thermopan.com/collections/thermo-pans

I can find it for sale on the web, https://www.supplyhouse.com/Thermopan-16050-16-x-47-5-Ultra-Fire-Resistant-Duct-Panning-Sheet

I will also check at local HVAC places.

Here are some good duct pics from a similar camper to the pics above that I am working on restoring now. I restore mainly Sunlines, but have worked on other brands too.

It is 1/4" foam board of sorts. Foil over the outside, none on the inside. It appears is was made from flat sheet, then V cut at the corners, folded and taped at the one and only seam.

This section is close to 8ft long. I have the roof all apart and can pull it out of the rafters.


The inside


You can see the angle cut corners


1/4" thick, 2" outside depth


Here is the plugged end. 2" tall x 7" 1/2" wide, wood plug in the end.






A cut out for a ceiling duct.


I had thought about possibly creating this out of metal as was suggested, but then decided this is not good in this RV attic situation. The unvented RV attic can get way over 100 deg F in the summer. The metal conducts heat well and cold too. When the AC runs, the metal hot duct is an added heat load due to the stored heat energy in the metal. And when it starts cooling, the cooling then can convect off into the attic. This appears to add high inefficiency to the system. The RV industry used foam board with foil on the outside. The outside foil I believe can help reflect heat off the duct and the foam board at least does not conduct heat or cooling as fast as metal would. Plus with the RV, foam board is mostly likely cheaper, lighter and easier to work with = $$$ saved.

I found 1/4" residing board at Home Depot, but you need to by 50 ft of it. It's an option, just there will be a ton of waste doing 1 or 2 campers. https://www.homedepot.com/p/Owens-Corning-FOAMULAR-1-4-in-x-4-ft-x-50-ft-R-1-Fanfold-Rigid-Foam-Board-Insulation-Sheathing-21UM/100320301

If anyone else has something to add on where to get the 1/4" foam board, ideally with foil on one side, it will be greatly appreciated.

Thanks

John