Converting air conditioner ducted to ductless

Typically the air return is on the ceiling air conditioner itself (with a foam filter under a cover grille), and the ducts are for the conditioned air distribution. Most ducted air conditioners also have a sort of blast door shutter arrangement which can be opened to permit most of the conditioned air to exit straight from the unit rather than heading down the ducts.

I'd think you could just stick the new unit in place and not worry about the existing ducts at all. It should be shrouded so that little if any air flows through them. If it looks like it would, you could just block them off. The one thing you definitely want to avoid is having an opening between the air return and the air conditioned side of things, allowing the cooled air to circulate through the air conditioner but not the room.

Do you have a thermostat? If so where is it? I just went from a ductless a/c that was salvaged from a wrecked trailer and put it in my ducted trailer. I had to purchase a ceiling assembly to make the conversion so that my wiring and thermostat would work. It should be the same process but in reverse for you.

LanceRKeys wrote:
Do you have a thermostat? If so where is it? I just went from a ductless a/c that was salvaged from a wrecked trailer and put it in my ducted trailer. I had to purchase a ceiling assembly to make the conversion so that my wiring and thermostat would work. It should be the same process but in reverse for you.

I bought the ceiling assembly specific for that AC. The original AC was controlled by a thermostat unit on the wall, but this one has a control board on the underside of the assembly, and a remote.

LanceRKeys wrote:
Do you have a thermostat? If so where is it?

Craig95005 wrote:
I bought the ceiling assembly specific for that AC. The original AC was controlled by a thermostat unit on the wall, but this one has a control board on the underside of the assembly, and a remote.

The top unit is the same, regardless of whether it's installed as a ducted system or whether installed as a direct blow, what you're calling "ductless". The difference is a ducted system will have just a ceiling grill and a thermostat installed on wall in the trailer while a direct blow will have a ceiling ADB (air distribution box) that has all the controls and thermostat built into it. Usually one would purchase the top unit separately so the question is - why would you have purchased a direct blow ADB along with the top unit when the original installation was ductless? :h You haven't said why you replaced the A/C but if the answer is because the top unit had failed why would you simply have purchased another top unit rather the replace everything? Older, non-current model, or you wanted different features, or what ....? :@

Certainly you can install these 2 pieces as a direct blow system but your existing wall thermostat would then not control the A/C nor would any of the cold air be distributed by the existing ducting. You'd likely also perceive the direct blow installation to be noisier than a ducted system simply because all the noise is concentrated in one area where the A/C is running.

SoundGuy wrote:

Certainly you can install these 2 pieces as a direct blow system but your existing wall thermostat would then not control the A/C nor would any of the cold air be distributed by the existing ducting. You'd likely also perceive the direct blow installation to be noisier than a ducted system simply because all the noise is concentrated in one area where the A/C is running.

The old unit was way too noisy (including a clanking sound) and the one I bought is supposed to be much quieter. I'm beginning to think the old one was ductless and just used the two ducts as return air. The reason for using the remote is better control over fan speed plus it has a heat pump for heating in the winter which wouldn't have been controlled by the wall thermostat.

Craig95005 wrote:
I'm beginning to think the old one was ductless and just used the two ducts as return air.

You're confused - as DrewE already described an RV air conditioner typically draws air in through the ceiling shroud, not cold air returns as does a home A/C. Those ducts you have and the fact your original A/C was controlled by a wall mounted thermostat says clearly it was a ducted system. What you've purchased is a direct blow system - a top unit plus the ceiling mounted ADB which blows air directly out vents and into the coach, no ducting involved. There's nothing wrong with this but you'd want to seal those two ducts you mentioned and of course the wall thermostat won't be used for controlling the A/C because the ADB itself has all the controls mounted on it. And as I already mentioned, you may perceive any direct blow system to be noisier than a ducted system because all the noise is concentrated in one area where the A/C is located.

As said before the only difference is the inside unit and the thermostat. The outside units are the same.

I have a Atwood non-ducted it one end and a Atwood ducted at the other end of my 5er. I think (?) the the non-ducted inside unit will block the ducts you have with no modifications. Simply install. However, if I am wrong, I do not see any problem with the non-ducted inside unit blowing some air down the ducts.

However, if I were you I would try to swap the non-ducted inside unit for a Ducted inside unit. I think you will very happy with the atwood. You can alway run the ducted unit as a non-ducted unit by closing the slides tabs which open the A/C to fast cool.

TenOC wrote:
However, if I were you I would try to swap the non-ducted inside unit for a Ducted inside unit.

The problem here being the OP's original thermostat may not work with the new A/C he's selected, especially since we have no idea (because he never told us) what his original A/C model may be, nor what thermostat he has. If his new A/C requires a new thermostat which requires it's own specific wiring then fishing that wiring through the walls could prove to be quite difficult.

I installed an Atwood Air Command 15,000btu unit on my trailer a year ago which replaced a Dometic DuoTherm 15k unit. The new one does require a new thermostat but it is a 4 wire device and the place that did my install was able to easily wire the new thermostat to the existing wires.

I agree that the OP most likely had a ducted unit originally and his best bet would be to return the non ducted unit in exchange for a ducted one. The difference in air handling would be a big reason for me. I would not want all the cool air being directed into one place. The noise alone would be considerable let alone the lack of cooling in the places farthest from the air conditioning unit.

I believe that in smaller trailers a non ducted unit would work fine but seeing his original one was ducted I doubt he has a small trailer and he will be disappointed in the performance and noise of the new one. Despite what the advertising says, the unit is not quiet and can be disturbing if you are trying to watch a television in the close proximity of the mounting location - at least it bothers my wife. :R

BarneyS wrote:
I believe that in smaller trailers a non ducted unit would work fine but seeing his original one was ducted I doubt he has a small trailer and he will be disappointed in the performance and noise of the new one. Despite what the advertising says, the unit is not quiet and can be disturbing if you are trying to watch a television in the close proximity of the mounting location - at least it bothers my wife. :R

Our previous KZ Spree 240BH-LX had a ducted Coleman Mach 3+, our current Coachmen Freedom Express 192RBS is equipped with a direct blow Dometic Brisk II and although the latter certainly does cool our 19' trailer just fine it literally screams noise so we only use it when absolutely necessary. No question in my mind that the ducted system was quieter.