AC replacement

[Acdii]

I am doing dome upgrades to my Coleman 274BH, new larger jackknife, new kitchen sink, new queen mattress, all arrived today, but the one thing that I have yet to order is a new AC unit. Currently it has an advent 13,500 ducted unit. two reason I want to replace it, it barely keeps up on hot days, and its too tall for my barn. In order to store it I have to climb up and remove the outer top shell, then in spring blow all the dust out before putting the cover back on.

So I am looking at the Mach 8 Plus with is only about 8-9 inches tall, perfect, but I can't seem to figure out what besides the unit I need for it to work in the trailer besides a new thermostat. I also don't want to break any seals until I am ready to swap it out, though it looks like from what I can see, 6 screws hold in the grill, and then four long bolts attach the unit to the roof, but looks like there are components in the middle.

I guess part of my confusion is that the Advent uses manual doors to change it from grill to ceiling ducts, and some AC units use controls instead.

Has anyone done a brand swap out before like this? It will be the Mach 8+ 15K unit, the grill I have now is Advent ACRG14.

[Acdii]

Thanks, I have found the Dometic is under 13" and will work at a lower cost. I have a question out to one of the sellers about the control unit and plenum to see if the Advent will work with it. I noticed from looking at the Dometic plenum, they are very similar to what is installed in mine already. Where the real question lies, do the bolt holes in the clamp line up with the new AC unit, if they do then it will work.

[wa8yxm]

The New A/C will come with a new seal and will fit in the same hole.. So long as the number of wires between the T-Stat and the AC is the same or less. you will have no problems. You might not even need a new T-stat... though there I can not be sure.

I have done two 13500 to 15000 upgrades One new T-Stat one uses original controls.

[Joe417]

You may have already seen this but Airexcel(Coleman) has a ceiling plenum selector. The plenums fit any of their ACs.

https://www.airxcel.com/coleman-mach/products/ceiling-assembly-selector

Adventure RV offers the Mach 8 with a non-ducted plenum for less than $1K.

There's little price difference in plenums so if you decide exactly what you need and call them, they may make you a better offer than you see online.

[Acdii]

I think I understand the differences for ducted/non-ducted and Multizone units. Ducted multizone apparently has no grill inside, and the unit is a top down mount. non-ducted can be either direct vent through the grill or have ducts and vents in the grill that close off, and ducted can have just an intake grill with no ceiling vents next to the intake.

What I have is the kind with the grill vents and the plenum is sheet metal attached to the unit and the control box attaches to that and the cross member on the ceiling clamp.

Currently my ac unit with the shroud removed is 14" from the top of the roof. So what I am looking for is a unit that is just under 14" at the most with the shroud intact.

Two units are low profile, the Dometic Penguin II and the Coleman Mach 8, but both are at least $1000 without the control unit or grill. However I did find a Dometic unit that is 12.7" installed and is less than $700 for the 15K unit. Now I am trying to find the right ceiling grill and control unit. There is also the option for a heating unit that goes in the duct side.

The install is not complicated in any way, its locating the correct parts for the application that has been a bugger.

[Joe417]

There's nothing sacred about the seal under the AC. It's a closed cell foam ring that goes around the opening and compresses when you tighten the 4 inside bolts. It is re-usable if it isn't crushed too flat, although I have seen a couple that someone put dicor on both sides of the gasket before setting the AC. They were a mess to clean up.

There may be components in the middle but all that I have worked on stay on the AC when you lift it up.

When you change manufacturers you will have to buy an inside plenum for the ducting to match the AC. They pretty much universal.

My only suggestion would be to buy a simple one that uses a standard thermostat. None of the fancy microprocessor garbage, as they are more opportunity for failure.