wall unit a/c replacement

[NorCal Gordo]

Howdy all! I've got a 1999 2720 with the original air conditioner in the cabinet next to the stove. If I were to replace it, do I need one specifically made for an RV or may I just get a window unit that has the correct dimensions for the space? I'd assume that accommodation would have to be made for water drainage with another non-original unit. Thanks!

 

[Shrimpburrito]

See Bill's post in this thread (post #3):
https://www.trailmanorowners.com/forum/showthread.php?t=18366

I remember HarveyRv's modification, and he wrote a beautiful thread about his modification, complete with pictures. Unfortunately, I can't seem to find it, and further, he's not even listed in the member list anymore. So I'm not sure where the thread went.

Bill - any ideas?

Dave

 

[commodor47]

Dave,

I found harveyrv's posts by doing a Google search for "harveyrv trailmanor". I believe this is the thread you are looking for - minus any photos. The photos may have been left behind during one of the forum software updates?

https://www.trailmanorowners.com/forum/showthread.php?t=7477

Dick

 

[Shrimpburrito]

Nicely done, Dick. I was searching for the thread using "harveyrv" as a user, and since he was not in the user database for some reason, no threads were returned. Thanks for finding it!

Dave

 

[Bill]

I found it, too, but I am slower than Dick. As he noted, the thread is

https://www.trailmanorowners.com/forum/showthread.php?t=7477

and Harvey's posts are #11, #13, and beyond. Unfortunately, the pictures are missing. I hate those external super-duper picture hosting sites that disappear in the middle of the night, and take your pictures with them. But that's a rant for another day.

The idea is this. A window air conditioner has two physical halves - a front half and a back half. In normal household use, the front half protrudes into the room, and the back half sticks out the window. There is a reason for this.

The front half takes in room air either through the grille on the front (usually near the edges) or on slots on the side, near the front. It cools this indoor air, and then blows it back into the room through the front of the unit.

At the same time, the back half takes in outdoor air through the back, or through slots on the side but near the back. It heats this outdoor air, and blows it back outdoors.

It should be obvious that you need to keep these two air paths separate. When you install it in a TM, the back half doesn't protrude outside, but you still need to direct the air in the rear air path outside of the TM. In particular, you must not allow any of that hot air from the rear path to enter the TM.

What HarveyRV did was to grab a sheet of aluminum flashing, and cut it and bend it so it would direct the rear half airflow into the unit and back out through the side of the unit, while the unit is mounted in a TM. None of the rear half airflow was allowed into interior of the TM.

The details of how to cut and form the flashing were in the missing photos. Not a big loss, because the details will be different for any other make/model of air conditioner, because the grilles and slots are in different places. You need to bend and cut the flashing to match your air conditioner, not his.

So as long as the air conditioner fits in its proper location, and you are a bit inventive, you should be able to do the same.

Bill

 

[Shrimpburrito]

Great summary, Bill. Also, as I think I maybe pointed out in that thread, there are AC units intended for windows and those that look very similar but are intended for walls. I've never looked into it to get the specifics, but I suspect the vents are in different spots -- in a wall unit, for example, the sides are likely enclosed on the wall, making side vents ineffective. So maybe a wall unit would be easier to direct that hot air outside, I don't know, but just thought I'd throw that out there.

Dave

 

[Wavery]

Howdy all! I've got a 1999 2720 with the original air conditioner in the cabinet next to the stove. If I were to replace it, do I need one specifically made for an RV or may I just get a window unit that has the correct dimensions for the space? I'd assume that accommodation would have to be made for water drainage with another non-original unit. Thanks!

Hi NorCal Gordo,

If you are still interest in doing this mod, most of the work is done for you (because of the previous A/C). If you are still interested in do this, I will spend some time going over how to improve on the factory installation so that the A/C will actually work. The factory installation was not done very well.

 

[Shane826]

Wavery- I’m interested. I have a project 2000 2720sl and I’m pretty sure the A/c is toast.

 

[Wavery]

Wavery- I’m interested. I have a project 2000 2720sl and I’m pretty sure the A/c is toast.

Isn't your A/C unit on the roof?

 

[Shrimpburrito]

The AC on my 2000 2720SL is wall mounted….

Dave

 

[Shane826]

Nope it’s in the cabinet.

 

[Wavery]

Copied and pasted from 8-04-2008 thread.

===========================

I did take pics but not a lot. I'll try to describe as I go here.


This pic is the inside of the cabinet. Note the pre-existing 110V outlet in the back right side of the cabinet.


I started by drilling 2, -1/4" pilot holes from the inside of the cabinet, 2" from the cabinet bottom. This gave me orientation to take measurements on the outside. Once my lines were drawn, I drilled a 2" hole with a hole saw to start my cut.

Once the hole was cut through the trailer wall, I went inside and cut the cabinet out. I left the bottom lip of the cabinet because that lifts the front of the AC to allow for drainage. I was then able to insert the AC from the inside.


When cutting the outside wall. I found that it cut very easily and it was very clear when I came to any framing. It was like hitting a brick wall with the fine tooth cutting blade. That told me where to stop and actually made the job easier than I expected.

I cut the wall outward until I hit the framing. This left me about 2" on the right (from the outside) and 5" on the left. There is a frame member on the left that I left in but there is still 3" of cabinet that can be opened up. I will Open the remaining 2" (leaving in the 1" frame member), if I feel the need for additional air flow.

The openings on the sides are for outside air intake to cool the condenser.

After I water-proof the cabinet and install the outside grilles, I will put 2 pieces of sheet aluminum (painted to match the trailer) on piano hinges so that they can be opened up while the AC is running. These will act as baffles (like the pieces of cardboard that you see in this pic) to keep the hot air that is exhausting from the back of the AC from being recirculated back into the cabinet.


Notice in this picture, I cut out the louvered vents on the side of the AC housing to allow for increased air flow.


I feel that the reason that so many people have issues with these side mount AC units is because the factory may not have allowed enough outside air flow for the condenser. There is also nothing to keep the hot exhaust from being recirculated back into the condenser. I'm a little surprised that they work at all, the way that they are installed.

The AC is working quite effectively with those cardboard baffles. Without them, it was struggling.

I will put 1, 15"x 18" grille behind the AC unit for the exhaust and 1, 15"x10" on either side of the AC for fresh air intake.

I'll post more pics when I'm finished.

 

[Wavery]

This is a combo-unit. It says that it comes with a sleeve but it didn't. I wouldn't use it anyway. The way that I opened up that wall allows for sufficient fresh air to enter the cabinet and flow through the condenser.

I thought about putting a catchment tray in there and installing a drain. It has to many possibilities for problems such as you mentioned.

I have decided that a better option is to fiberglass the inside of the cabinet, thereby making the cabinet itself, "The tray". I will take the F/G all the way to the outer edge and even grind a couple of small notches in the outer wall (that will be sealed with F/G) to allow for water to just run down the side of the camper. After-all, the roof air just runs down the roof and down the side of the camper....

I'll post more pics as I go. I wasn't very good at taking pics at the 1st part of this project because I didn't know if there would be much interest.

===================================

I just finished waterproofing the cabinet bottom about 20 minutes ago. I outlined the area to be waterproofed with 1/4 round molding. Then I laid in a layer of 8oz fiberglass cloth, poured the F/G resin on it and brushed it in with a brush. The 1/4 round is used because F/G does not like to make right angle bends. It will just pull away from the surface as it hardens if you go more than a 45 degree bend. In areas where you can't make that bend, you just lay the glass cloth flat on one surface. Then cut another piece to lat flat on the other then fill the joint with resin.

After about an hour of dry time, I'll go out and trim of the excess cloth with a razor blade. By tomorrow morning that cabinet will be as waterproof as some bathtubs.

You'll notice that I left the outer edge flat so that water can just drain down the side of the camper. Just like the water drains down the roof on your camper.

 

[Wavery]

=========Edited from 2008 post:===========
This is probably the most important part of this mod and where the TM factory failed in their installation for that A/C.

It is crucial that the hot exhaust air from the A/C condenser (the square mesh part on the very rear of the A/C) be separated from the air intake that is located on the sides of the A/C and actually inside the cabinet. I accomplished that with a wider opening than the factory opening and those wood dividers that ultimately separate the air-flow. Once the outer grille is installed, the hot air is directed out and down and the cooler (outside) air is directed into the cabinet from the side directed fins on the grille.

The factory installation has the air for cooling the condenser coming from inside the TrailManor, going through the condenser them being exhausted to the outside. What that does is create a vacuum inside the camper and that vacuum is filled from drawing hot outside air, into the camper. That actually defeats the concept of the entire idea of recirculating inside air through the evaporator side of the A/C. What this mod does it keep only cooled air inside the camper and recirculates only cooled air through the evaporative side of the A/C unit. This is how your A/C works in your home. The condensing unit is totally installed on the outside of the house and the hot air from the condensing unit is exhausted totally to the outside and the cool air from the evaporative side of the house is recirculated totally inside.

I hope that make sense.
============================


It's a warm day so the F/G set up pretty fast. I went ahead and finished it up.

I installed framing that also act as air separators behind the AC unit. They are screwed into the frame members of the body with "L" brackets. Then I used metal braces that screwed into the new braces and into the back of the AC unit. This will keep it from bouncing on the shelf and damaging it. This also holds the AC firmly in place.


Then it was time to install the outer grilles.


I'll attach the air deflectors by pop-riveting a piano hinge to the grilles. When the AC is not in use, the air deflectors will cover the 2 outer (air intake) grilles.

 

[Kmikesell]

Not my circus, and not my monkeys... But great pix and explanation. Thanks for sharing!

 

[Shrimpburrito]

Great to see these photos again. Am I missing the sheet aluminum that are mounted with piano hinges, swinging into place when the AC is in operation?

Dave

 

[Shane826]

Wow that is fantastic. I do remember reading that post a while back but without pictures it’s kinda confusing but now it makes sense. Do you have details on the waterproofing?

If there’s room would it be worthwhile to add a couple fans pulling air through the condenser and pushing the hot air out the vent? I’m thinking like the radiator/condenser fan in your car.

 

[Wavery]

Great to see these photos again. Am I missing the sheet aluminum that are mounted with piano hinges, swinging into place when the AC is in operation?

Dave

For some reason, I can't locate the pics of those baffles.

Pretty basic though. I just cut 2-pieces of white sheet aluminum to cover the side exhaust vents (on the outside grille). I used a piano hinge on each to attach the baffles to the grille and a simple lever on the outer side of the baffle to lock it in place while traveling. The whole purpose of those baffles is to keep rain water and debris out of the cabinet when the A/C is not in use.

There is no real need to cover the center part of the grille because the lovers point down and prevent most water intrusion. If a small amount of water does get in, it's not harmful because everything inside the cabinet (including the 2 vertical air separator pieces was covered with a coat of fiberglass (I used epoxy resin for ultimate water resistance).

EDIT...
Now that I look at the pics again, I remember that the outside grille is made up of 3-pieces.

 

[Wavery]

I guess that I should include a picture of the inside.

 

[Bill]

Really nice job! Thanks - so many folks are interested in this.

Bill