Window AC in generator compartment? (Scott or anyone else)

[Blue~Go]

A mid-project update:

I went with a 5,000 btu window AC, because I only have about 12.5" of "wall" inside the Chinook. Scott had more vertical clearance and a fiberglass box, and I'm thinking that's because the Premier has a shorter refrigerator? Or they finally read the Onan specs which call for a fire-resistant box? At any rate, the gen box on my era Concourse is thick (surprisingly thick) galvanized , and is an inch or so shorter (vis-a-vis the interior hallway floor) than his era fiberglass box.

Most 5,000btu window AC units are around 12" tall by 16" wide. There is one I found by LG that is 11" tall and 17" wide, but I was reluctant to use a non-standard size in case I need to replace it. Also the LG projects into the "room" almost twice as far. I ended up buying them both and as it turned out (at least on the Toshiba 5,000 btu window unit) that they were both about the same height in terms of what projects into the room (which is where I had my height issue). So I went with the standard sized Toshiba.

I had to scratch my head a bit to figure out how to support the unit and still get it into the compartment (and be able to reach in and tighten screws, etc.). Reason is that the gen compartment floor is 4" lower than the Chinook inside floor. I decided to push the AC into the Chinook from the generator compartment and do all the securing and supporting outside in the compartment. So I cut a hole in the side of the gen box facing the hallway that just fit the part of the unit that projects into the room. I will make a panel to cover the interior side up when not using the AC (which will be nice anyway rather than looking at galvanized steel box).

I started with a fancy cradle, but then realized it wouldn't actually work due to height restrictions going into the compartment, and similar trying to get it onto the cradle after inside (oops). Ultimately I settled on two separate crosswise "cradles," one at the front and one at the rear (outboard side). The front legs of the AC are bolted to the front one, and the back one has cleats. These are screwed to the floor (and I made a sub-floor since the original floor has huge holes from the generator exhaust, etc.). If this all works out, I will probably replace the screws with Tee nuts or similar. This way the AC isn't going anywhere (I didn't want to have to disassemble to drive), but yet there is no attachment or etc. inside the Chinook.

I realize now I should add some photos, but I haven't taken any yet. If it all ends up working I will do that; otherwise, never mind

For now I'm just running an extension cord out one of the convenient floor holes (in the gen compartment), but if it works out I'll wire up an AC outlet in the compartment (the cord could also come into the Chinook to plug in if desired).

So I fired it up on a lovely, 100º evening and ahhhhh, instant coolth! Delightful. However, after an hour when I was checking on it, I found that the "ceiling" of the generator box outboard of the AC was getting quite hot. No harm done as it is galvanized metal, but that's obviously not sustainable. The area I was worried about -- where there is only about 1.5" above the AC until the compartment ceiling -- was fine. It was the ceiling outboard of the AC. So the heat was leaving the AC and then just sitting there. I had a 270cfm fan on hand but that didn't seem to do anything. So, back to roasting while I ordered a couple of fans to try (one 7xx cfm that I know will fit; one 1,000+ cfm that may be too large).

I also whipped up a shroud/septum type thing out of some galvanized flashing I had lying around. Nothing fancy, but basically a top that goes from the back of the AC unit to the compartment door (so heat won't get up to the ceiling), and then two partial sides so that the cold air intakes are separated from the outgoing heat. I will put the new fan in this "shroud" blowing outward and give it another try, then report back.

[Blue~Go]

Just thought I'd update this post with two summers' use under my belt (and those were HOT summers, with temps over 100º for days on end) (trapped, don't ask).

So to re-cap, I removed my roof air-conditioner many years ago and replaced it with a skylight. All good there. Still love the skylight and the lack of a 110# beast up there.

A couple years ago, I realized I'd been lugging around the Onan generator for years and had never once used it as a generator. Okay, that's gotta go.

Then I had a big, beautiful storage compartment, and around 175# of new cargo capacity.

Right around that time you-know-who came to visit the world and I ended up spending the summer of 2020 (and then 2021, grrrrr) in a very hot place. I did have access to shore power.

I considered putting a 9,600 btu Coleman Cub type AC on the roof (could run on an EU2000 and also a bit lower profile than the bigger units), but.... I still didn't want that beast up there. Hmmm, what to do? Well that was easy: Ask member Scott how he rigged up a window AC in the generator compartment (he's always got good, out-of-the-box-thinking ideas).

Done and done. (Thanks, Scott.) With the generator compartment door closed, you'd never know the window unit was there, and I still have a fair bit of storage space. I put it on a painted wooden cradle that is removable, so with about 10 minutes I could take it out and go back to having the storage and/or put it back in and have the AC again. It's also plenty secure for driving with the AC unit in place. Now how would it work? The first time I ran it I took a lot of measurements with an IR thermometer and I decided that too much heat was building up inside the old gen compartment. The compartment is made of heavy gauge steel (from Chinook), but still I didn't love it and I'm sure the AC unit did not appreciate it either.

So, I took some flashing and made a little shroud for the back of the AC unit (so the incoming air is outside the shroud, and the hot air is inside it) and I mounted a ~10" box fan between the back of the AC unit and the compartment door, inside said shroud. Voila, success. I could run the AC unit indefinitely (and did) and nothing got too hot. I just set the box fan on low blowing out whenever the AC is running. (I also have the door to the generator compartment open all the way, or optionally propped at 90º if it's raining.)

I like that the cold air comes out in the hallway instead of right on top of my head (so both the cold blast and the noise are "out back." I thought at first I'd have to run a fan to distribute the cold in the Chinook, so I set up a 20" box fan in the hallway pointing forward. But then I tried it without that (inside) fan and it was just fine. So all I did was aim the AC vents up and forward and everything got nice and cool. I did have the cab closed off with a blanket; that might have been too much to ask in 110º temps

It was not humid where I was, which of course helps. On the other hand it was 109ºF day after day, and I was reasonably cool inside then, and then cool as a cucumber (which is warmer than a meat locker but still nice and cool ) in anything under 100ºF. I ran it most of the summer of 2020 and all of 2021 (which were dang hot) and it's still cooling away no problem. (Well actually right now the generator door is closed and you'd never know it was there; but I mean after two summers, it's still running along just fine.)

I found it a great comfort in 2021 -- when many things were unobtainable -- that I had a spare matching window AC sitting in storage just in case ($150 x 2 gave me one to install and a spare from Home Depot).

I found a side bonus this spring, when I needed to spend a week in an even hotter locale, off grid. I absolutely despise listening to generators, and would not want to subject anyone else to that; but one advantage of camping in 110º weather is .... there is no-one else within miles (no one else is that stupid ). So, no-one to bother.

My buddy (who was also there in his RV) bought an EU2200 to power his roof AC (13,500 btu typical RV roof unit). Well, it worked, but that thing was running flat out. Super noisy, and he had to refill the gas constantly. I tried it with my window AC. It ran basically at idle in Eco mode and sipped fuel. Much better. Turns out it will also run on an EU1000 (which I think I could store in the gen compartment next to the AC, but wouldn't be positive unless I bought one and modified the feet slightly).

Lastly, I am considering making the switch to LFP batteries (always figured I might when my Lifelines were ready for retirement). With the window AC and the fan together only being 650 watts (13,500btu roof AC is closer to 2,000 watts), and LFP's resistance to being defeated by Peukert type loads, I could run the AC on my own battery bank for an hour or two without needing the world's largest battery bank/inverter setup. Not that that's a drop in the bucket in super hot temps, but it might be nice for either running into a store or museum with the pup along, or taking the heat down a notch in the evening of a warm day before hitting the sack (obviously as always, you need a way to put the power back, but that's an easier proposition when it's 1,500 watts for a couple of hours vs. 4,500 or so). If driving the next day, or if one has a lot of solar, it's an option. I'd call that a side benefit not a main reason.

So in summary, it was pretty easy to install the 5,000btu window AC (thanks for the tips and the initial idea, Scott) and it's completely reversible. No giant/heavy unit hulking on my roof plus I have a skylight and nothing shading any solar (and it looks so sleek up there sans AC). And a unit is easily replaceable at any box store for around $150.

Definitely not the best choice for everyone. I imagine the roof AC and Onan suit most just fine. But it ended up being a great option for me and I've been super happy with it, so I figured it might be interesting to someone else as well.