Adding A/C duct

[Thurman]

TT in question: 2015 Coachmen Freedom Express 310 HBDS. This unit has the 15k A/C with ducted air and the quick cool grill. The problem: There is no A/C to the bathroom and it gets too hot in there to take a shower at the end of the day. I started using a small fan to move cooler air from the interior of the unit into the bath area so we could take showers or do our business. There is also no heat to the bath area but that is not a problem as it doesn't get cold enough down here (S. Ga.) to use the heater. If I wanted to run a heating duct into the bath that will not be a problem. For some reason there is a heating duct/register down low on the wall between the fridge and bath door. This is on the opposite side of a bath area wall and why they didn't add a register into the bath area I just don't know. I see no problem with tying into the heating duct and adding a register in the bath. But the A/C is a different story. I understand how they make the ducting for the A/C in the ceiling but why they didn't make this short (less than 36") run into the bath area I don't know. The selling dealer states that they have never seen anyone add an additional ceiling duct to any RV. They don't know me very well. There is 1 1/2" styrofoam above the decorative ceiling material that the ducting is cut into. So I am working on a way to cut the additional run of ducting into the bar area through this styrofoam. The factory duct runs are 1 1/2" high by 4" wide throughout the unit but I don't think I would need this new one to be but 2" wide for the bath. Where the factory ducting was cut into the styrofoam you can see the plywood of the roof material. I'm working on coming up with some type of cutter that can be pushed into this styrofoam to cut out a 1 1/2" tall by 2" wide duct. Has anyone else done something like this or know of a way to do this?

[Evereddie]

In my little RW 2306 there are actually ducts cut into ceiling for vents in the bathroom that were sealed up and not used. Was told that they use certain roof systems for many camper models. Maybe there is a chance you have ducts already in the ceiling. Pull off the last vent covers before the bathroom and look up in it.

[Thurman]

This has been done. All of the A/C registers in the ceiling have been removed to determine which way the ducting system runs. From the A/C unit there is one straight duct to the back room of the TT. From this there is one register for the dinette area and one register in the back bunk room. To do what I want to do I will need to remove the register at the dinette area to make the duct to the bath area which will be 90 degrees from the dinette register. It's a do-able challenge, I just need to invent a way to cut through the styrofoam to make that duct run. As a retired machinist/toolmaker I have too many ideas running through this old noggin of mine. I need to narrow the ideas down to some type of cutter that I can make in my shop at home. Styrofoam is not that hard to cut, I just need to figure out how to feed a cutting tool into the styrofoam the length of the duct I want to cut and to remove the waste styrofoam. Back to the thinking board.