Convert AC from ducted to non-ducted

TomG2 wrote:
How big of a deal would it be to convert a typical Dometic 13.5k btu roof mounted RV air conditioner from ducted to non-ducted? Is it a do-it-yourself project for a typical RV owner? I have a newer model with the three button electronic wall mounted thermostat.

You haven't told us just which "typical" Dometic A/C you have but whether it's an older BriskAir or the newer Brisk Ii the top unit is the same whether it's ducted or non-ducted so all you'd have to swap out is the ADB (Air Distribution Box). Since all A/C control will then be on the ADB you'd lose the ability to set the A/C to Auto and have it cycle on / off completely as you now can with the wall mounted thermostat. Instead, with the direct blow ADB the fan will run constantly as the compressor cycles on/off according the setting of the thermostat that's part of the ADB. IIRC Dometic does offer a wall mounted thermo designed to be be used with their non-ducted ADB but I'm not sure if you could use the existing wiring loom from the A/C to the current thermostat or would have to replace it. For more info I'd suggest you take your A/C info to your local Dometic dealer and have them correctly identify the correct ADB, and wall mounted thermostat if your current one isn't suitable. I've owned Carrier, Coleman, BriskAir, and now have a Brisk II in our current rig and IMO our current non-ducted Brisk II is noticeably louder than the ducted Coleman Mach 3 Plus we had in our previous Spree but it does do the job.

It is really pretty easy- you need the a non-ducted air distribution box (they make them for both manual control and your wall thermostat), probably a kit for thick roofs (just a longer supply duct from roof unit to adb).
The only issue would be sealing the old ductwork, as the unit will draw return air though it, which isn't bad, but it won't be filtered. Other than that, it's all plug and play.

look to see if your cover, air intake has a closed vent to the output duct, If so, just opem your vent, and bingo! a Non-ducted unit!

The "Why" is that I have owned both and prefer the non-ducted. Perhaps I just like to tinker. Mine has the "Dump" feature, but I would really prefer a true non-ducted system. I like things simple.

My big question is why?

I had ducted air in my 1985 class C, while I looked forward to the distributed and much quietier ducted air in my new 97 class C.

While it might be possible, it is not all that easy, as they do not make a interior grill that is non-ducted to install on a ducted A/C unit.

There is a company that makes a large vent that can be installed do it yourself on a ducted air conditioner interior grill, and it will blow a lot of air directly under the return air vent, quickly cooling the area within 3 feet of the A/C return air vent.

However that will blow directly down, and not distribute the air around the room.

It is likely that you will need to purchase a non-ducted air conditioner to replace yours to get the interior grill, and a rooftop unit designed to connect to that interior grill. Also most non-ducted air conditioners have the controls mounted to the interior grill, and just like a window air conditioner, they are 120 volt controls, not adaptable to a thermostat control. There are exceptions, where a remote control is used to control the built in thermostat of the non-ducted unit, but most are built in 120 volt controls.


Good luck,

Fred.