Plywood Ductwork ???

[scanzel]

On my Prevost I have retained the bus otr system. On the passenger side it will be all original windows with a side isle bathroom area. I want to duct the otr air and heat about midway along the base where the floor meets the walls to the back. I plan on building a duct 4 1/2 inches wide by 10 inches high from where the air comes up from below to the back sleeping area. Instead of trying to incorporate a metal or fiber board duct in such a narrow space has anyone ever just used plywood for a duct and painted it with some sort of paint to seal the wood against the cold air or heat. Thank you.

[artvonne]

  The R value of plywood isnt much better than metal, but its obviously much stronger. Maybe some foil backed foam inside if your concerned about heat loss.

[FloridaCliff]

Don't do it!

Sounds like a mold and mildew growing area to me.

Part of the ducts job is transport/protect the cold/hot air from condensating along the path to the vents.

The ducts need to be sealed and protected from escaping (insulated) to do this.

You could use a foil backed product, comes in 1/2 or 3/4, put three sides together, tape, duct seal, and then lower into your existing space.  Then use caulk type duct seal to put on the top piece.  Lots of options.

HTH

Cliff

[Brian Diehl]

I've built a fair amount of my ducting out of 1/4" plywood.  I just sealed it with marine spar polyurethane.  Works great without any condensation issues.  I like it because it is easy for me to work with and I have a ready supply plywood at my local big box store.

[muddog16]

I used this Ultra Duct, there are photos of my installation at my site below, it was way to simple to use!  Here is their link:  http://www.insul.net/prod_ultraduct.html



Here is a photo of what they make! The cost is amazing I did the the complete job on the bus for less that $180  and put it in in less than 5 hours!  I had them make my "T"!  Check it out!

[David Anderson]

Muddog,

Thanks for the link.  I bookmarked it.  That looks like a really good product.

David

[rampeyboy]

aside from not being flexible, why not use something like PVC pipe as ducts?

[robertglines1]

with the air volume you will get out of the factory duct with its deflectors..you might not need to duct it..if memory serves me rite on your coach the split side to back would require only about a 4 by 6 inch duct to carry that 1/2 of the air out of the factory duct...you could try a temp cardboard mock up to see what you need...the factory duct work on the 98 is just two sided attached to a masonite wall and a plywood floor for the bottom. so it is exposed to ply wood from the factory..Bob