Home Office Projects Series: Air conditioner setup

Many models let you run the condensate drain on your choice of right or left side. The unused side is often only supplied with a friction-fit drain plug. Over a period of many years, some of these plugs can shrink, not quite fall out, and then you get a real mess.

Make sure the drain pipe is dry. Clean it with denatured alcohol, then let dry again.

Buy a silicone sealant that carries a 20-year warranty. Buy a roll of "cork tape" [1]. Fill about 2.5 cm / 1 inch of the drain pipe with the silicone sealant. Stretch wrap the drain plug with the cork tape, so the tape thins out while sticking to the plug. Pinch/squeeze/roll the part of the tape that hangs out beyond the end of the plug so it is slightly smaller than the stem of the plug. Push the plug into the drain pipe, and try to push it all the way up to the head of the plug. The cork tape will fill out and adhere to the walls of the pipe. Finally, stretch wrap more cork tape (or self-fusing silicone waterproof tape if you don't like the stickiness on both sides of the cork tape) around the entire drain pipe and drain plug assembly, including wrapping the end, and seal up the assembly to the pipe.

Mount a very slightly tilted metal shelf underneath the mini-split air handler (the part that mounts on your wall inside your building), and install an AC-mains-powered moisture sensor that cuts off power to the mini-split when triggered, at the lowest end of the shelf. Mini-splits usually use a zero-capacity drain pan to stay as slim as possible, and if they clog up at the condensate drain pipe, they overflow rapidly (within minutes).

Learn how to take the plastic cowling off the unit before you mount it, document it by video or photographs, and stash it with your product manuals. Mini-split manuals usually don't show how to take them apart enough to get at the condensate drain, and most models I've seen have lots of plastic catches all over that are hard to see when you're standing on a ladder peering between the ceiling and the cowling. If you ever get biogrowth in it, you'll want to know how to take it apart.

Or, if you don't want to take it apart to get at the drain, you can codge together a way to run your wet/dry shop vac to mount to the condensate drain and pull stuff out. I used a shop vac mini kit [2]. I also got a venturi-based device to try to develop more vacuum [3] with the CO2 tank I normally use to make fizzy water.

[1] https://smile.amazon.com/DiversiTech-6-330-Cork-Insulation-B...

[2] https://smile.amazon.com/Wet-Dry-Accessories-VT1215-Attachme...

[3] https://smile.amazon.com/gp/product/B00CIRZGV6/

First off - if you're renting - you're not putting holes in the walls that go to the exterior and there certainly aren't any already existing. I've never seen or heard of that in the USA - particularly for apartments. Secondly - you're not hanging air conditioning units off the exterior walls of the apartment (rental or owned - you don't own/rent the exterior and ain't no residential building consenting to that shit). If you had a balcony, that's where it'd go, at best. Thirdly - where's your power coming from!? Most of these units are 220V and usually there is only one or two 220V power outlets in American homes these days and they're always dedicated to the washer+dryer. Maybe you have a third for an electric oven/stove. (Or an electric water heater) You'd have to run new power lines and that involves tearing up the walls. You could try to find 110V mini-split AC units but they're pretty uncommon in the USA (and much less powerful). As well, not having that AC on a dedicated breaker means you'll be giving up all other outlets on that breaker whenever the AC is on, which could be a lot of essential outlets in esoteric places.

Great insight for someone who lives in Japan and someone who wants to see what it looks like to install AC in Japan. Put it back in the title!

For heat, yes, but not AC. For example, the Mitsubishi MY-GL12NA is a very efficient mini-split with an EER of 13, but a random modern window or through-wall unit (ex: https://amazon.com/dp/B07D8R2V8H/) will have an EER of ~12.

Although I do wonder how that works with something like district heating/cooling systems, which seem to rely on centralized boilers and chillers to move thermal energy between buildings.