Installing window style AC unit IN bus?

[specialleb]

So my plan is to buy a 5000btu window unit and rig it up. Reasons, because I’m cheap

however i don’t want it sticking out the back. My idea is to build it into a cabinet over my kitchen. The back of it would be flush with the outside. Cut a hole for it to vent through. Insulate a “wall” around it. I’d put a tray under it to catch any drips and direct them out and down the side of the bus.


I assume if I build enough room around it for air to flow it should work fine but figured I’d ask first. Didn’t see a whole lot of threads on such a thing but maybe I missed them.

I figure if this works I have AC for $150 bucks and if something happens to it you simply pull it out and replace it at your nearest Walmart

 

[desrtdog]

I installed a window unit in my bus…posts #22 and 34 here have details and pictures.

You have not really said much about what you are hoping to get from this unit, specifically whether you are thinking it will be solely for use when parked, how you intend to power it (shore power only, or with batteries and inverter), how big your bus is, and what temp you are expecting to get from it (in particular as that relates to what ambient temps you will be using the bus in). With that in mind, I’ll offer a few observations based on my experience:

1. 5kbtu is not going to do a lot to cool a hot bus…at least not quickly. I have a 6kbtu unit, and with outside temps in the 90s+ it will keep the inside bearable once the inside is cool, but I also have 2 factory installed bus a/c units that are much better at getting the bus cooled when the engine is running. Regardless of what the a/c unit manufacturer says about “what size room” the unit will cool, if you have a full-size (40 ft) bus 5kbtu isn’t gonna cut it…
2. When running my unit, it will draw 400-500 watts….not a big deal if I’m on shore power, but coming from battery power, that equates to 40+ amps from the batteries to the inverter. I have rooftop solar and a beefy LiFePO4 battery bank, so when the sun is shining, that helps. Something to keep in mind as you plan your build.
3. When I was researching my build and looking at using a window unit, I came across a YouTube video of a build where they installed a window unit completely inside the bus, but neglected to isolate the part of the unit that would normally be inside the window from the part that would be outside (i.e., the evaporator from the condenser)…needless to say, they had to modify the design. I have my suspicions that a window unit that does not have unfettered airflow around the condenser section is going to operate a lot less efficiently - which is why when I installed mine I made it so it would actually stick out the window when in use….that won’t work if your idea is to use it while driving…

Some food for thought….Have a look at the link above and feel free to reach out with any q’s…

 

[nikitis]

Basic values are 12k btu for a 25ft cab(30ft bus) or less, Any larger of a bus you need a second AC Unit.

 

[sportyrick]

I cut a window unit in 2 parts with the condenser and compressor under the bus and evaporator and another fan inside. I did this 20 years ago so I have plenty of hot weather experience. It's 220V and 15000 BTU and most of the time it is sufficient in normal weather but in real hot weather is just isn't enough. Also if you expect it to cool down an already hot bus it won't. Even though my bus is 40 foot long we don't cool the back half (garage) so just consider it a short bus. Also half the windows up front are blocked off and insulated (6) but the rest are regular bus windows (6). A 5000 Btu might feel cool blowing on your face.

 

[nikitis]

@sportyrick Of all the people on this site, I'd probably give you a "Top Custom Award".

Your posts over the years have shown a lot of modifications done that most haven't attempted. I've gone back and read many of them retroactively. And you're bus has proven past the test of time for the work you put into it. Just thought you deserved that.

I'm curious to see how well my 12k btu Seer 22 rated AC works on my extremely well insulated 25ft cab bus (Minus the windows) I don't see many (if any) here doing 4in of xps on floor and 3in of polyiso on walls/ceilings and therefore don't have much data to go by for real world testing. I plan to test it thoroughly though and report back here regardless of the results.

I currently don't even have any diesel heater or AC installed in it yet. But it got down to 17F last night, and inside the bus it was 40F, I took temps. And that's just passive. Of course if it stayed 17F long enough the bus would get there as well, but it holds temps for a good while which is the point of the thick insulation. It's already telling me that I won't have to run the AC or heater all the time as the temps will hold for longer.

 

[sportyrick]

thanks nikitis, I am always interested in what you have to add to the conversations.