I tried posting in Home Improvement but nothing yet. Figured I would try here.
I am wanting to do a DIY unit in my 40' insulated container. My research shows about 20btu per sq ft. I have about 272 sq ft insulated. I should be fine with 6000-8000 btu. I have been looking on Amazon and prices are everywhere. Couple of questions:

Will it hurt to go with a higher btu unit like 12000btu?

Does anyone here have experience with DIY and recommendations on a brand?

Any help is appreciated. The little window unit sux in the summer in S. Texas.

Thanks.

Look into a dual splint/zone system instead of a single larger one if your budget allows. Better cooling/heating coverage.
https://www.amazon.com/208-230V-Ductless-Pre-Charged-Conditioner-Installation/dp/B0BWDV86M3

I've had good luck with my Mr. Cool unit so far. It was an easy install and it's going on 3 years now.

Quick question. How many square feet are you cooling and how many btu? I'm wondering if I get a larger Btu it will cool faster? This container gets hot when not in use.

I think it's about 480 sq ft. I dont remember the btu, 15-18k, I think.

It's best not too cool too quickly. You're better off with a unit running longer, so it draws more moisture out of the air. I think my monthly bill for that office is about $40-50, and that includes running a deep freezer.

I was thinking 12k Btu for 772 sq ft. It would only be used when someone is there.

For that SF you could use a 3/4 ton unit, but they are a lot harder to find than the 1 ton/12k BTU units.

Biggest thing you'll want to make sure is that it has a variable speed drive, otherwise it is going to be way too much capacity for that amount of space.

What type of power source are you using? That's also going to make a difference in your options. 230v would be better because it draws less amps than a 110, but if you are a on a generator odds are you'll have to go with a 110v unit. Not a huge issue really, I'll be installing a 110v unit in my deer camp cabin this summer as well.

Basically this is a deer/ranch cabin when we are working. I could run 240v if really needed but I would rather use the 120v already available since it won't be running all the time.

I checked, that's the size mine is and it cools that room very well.

For your size room, they recommend the 18,000btu unit.

Good deal. Thanks.

Get as large as you can. You can always turn it down if you start to freeze, but once you are maxed out, and still sweating your butt off, there is nothing you can do. In Texas with regards to A/C, always go as large as you can afford.

I use a 24k unit for my 600 square foot garage. I used a 18k unit at first and when it broke I went up a size.

The inverter ACs slow down the compressor to match the thermal demand so they don't cycle a lot like older air conditioners. So basically being a bit oversized isn't a problem.

I installed a DuctlessAire minisplit in January. It was pretty simple to DIY. Only issue was I didn't have the right fitting for my manifold gauge set and had to wait a couple days before pulling a vacuum.

Oh, one other issue. The high efficiency units have larger condensers and are quite heavy. I assumed it was maybe 90 pounds like some other minisplits but this shipping box was over 165 pounds and I herniated the L4-L5 disk lifting it up into the back of my vehicle.

ZihuatanejoMan said:

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Basically this is a deer/ranch cabin when we are working. I could run 240v if really needed but I would rather use the 120v already available since it won't be running all the time.

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I'll run this alternative idea in from out in left field -- To keep things super simple, cut a couple of 14" x 14" holes in the roof of the container and install (2) 15,000 BTU RV-Style 120 volt units (self-contained -- no lines to hook up) and call it a day. Each unit will pull between 15-20 amps.

As for BTU / sq foot, I'd rather have too much capacity in the Texas heat than risk sweating my balls off.

Just a thought ...

EDIT: I realize the roof isn't flat, but corrugated. But you could rig up some spacers to span the low points in order to seal.

ZihuatanejoMan said:

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Basically this is a deer/ranch cabin when we are working. I could run 240v if really needed but I would rather use the 120v already available since it won't be running all the time.

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Why don't you just cut a hole in the wall and put a regular wall unit for much cheaper.. we had a 40 foot container we used as a chemical lab, we bought a 10,000 btu wall unit, drilled 4 holes and cut it out with a sallz-all, anyway it kept the place freezing if we wanted it that cold, just used a 110 volt unit as well. If you do this put in the middle of the unit. Or put 2 smaller 6k btu on each end. It works. To frame it out, we cut the hole about 1" bigger than needed and just framed around the unit on the inside with 1 x 4 and foamed it.. looked nice

fullback44 said:

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ZihuatanejoMan said:

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Basically this is a deer/ranch cabin when we are working. I could run 240v if really needed but I would rather use the 120v already available since it won't be running all the time.

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Why don't you just cut a hole in the wall and put a regular wall unit for much cheaper.. we had a 40 foot container we used as a chemical lab, we bought a 10,000 btu wall unit, drilled 4 holes and cut it out with a sallz-all, anyway it kept the place freezing if we wanted it that cold, just used a 110 volt unit as well. If you do this put in the middle of the unit. Or put 2 smaller 6k btu on each end. It works. To frame it out, we cut the hole about 1" bigger than needed and just framed around the unit on the inside with 1 x 4 and foamed it.. looked nice

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OP already tried that...

Quote:

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Any help is appreciated. The little window unit sux in the summer in S. Texas.

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EComfort.com aka powerequipmentdirect.com

They will size the unit for you. Order. Do what you can yourself like mounting the machine and wiring the electrical if you're inclined. Then pay a local AC contractor to pull the vacuum and viola.
I'd suggest LG as a brand and go up a size or two regardless of your calculations.

Thank you. No holes in my container. We do have an insulated wall that is set back.

I have seen a lot of mr cool installs in person and eveyone has always had good things to say

clarythedrill said:

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Get as large as you can. You can always turn it down if you start to freeze, but once you are maxed out, and still sweating your butt off, there is nothing you can do. In Texas with regards to A/C, always go as large as you can afford.

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That's terrible advice for AC. Too big is worse than slightly too small. However, if it's variable speed, then it doesn't matter.

ZihuatanejoMan said:

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Thank you. No holes in my container. We do have an insulated wall that is set back.

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1. Will you have any kind of shade/cover over the top of it and any of the sides? I am in the AC business and put a 1 ton variable speed unit on my 40 ft container that has spray (closed cell) foam insulation from one end to the other about 2 inches thick and then another layer of open cell spray foam on the roof. I have NO COVER or shade trees protecting the roof. My lease is in Junction Tx. During the summer and during the day if I have it set at 60 degrees it still struggles to keep it below 85 degrees...with an outside high temp being 90 degrees or higher the steel roof just turns into an oven. Eventually around midnight it gets down to around 75 or so. The connex has a 1 ton Mitsuibishi mini-split.

I have built a 12x40 cabin and spray foamed it and it literally sits right next to it. The cabin stays at 65 degrees year round no matter what the temperature is- even when it's 105 outside. We built 2 bedrooms, a bathroom and a kitchen area. I have a 2 ton Daikin mini-split on this and it is a single condenser with (3) head units....one for each bedroom and 1 for the kitchen.

Just thought you might like some real world experience.

I built a shop and then a room within in. The main building has spray foam insulation. The wood portion of the shop is 35x15x8 and I use a cheaper model Traiden mini split. It does good, is wifi enabled and cools and heats well in an insulated shop.

https://traiden.com/

The problem we faced in our cabin was that it took forever to initially cool when we came out in the summer. So if you show up at 9pm don't plan on going to bed until midnight as the cabin has to go from 102* to 72(or whatever you prefer).

We went to a bigger mini split and then an extra window unit. That baby cools down quick and gets super cold which is nice when you've been working outside.

So go bigger!

Get a high seer variable speed and don't ever turn it off. Just set it to 78 when you leave. Don't know about diy brands available but the new 22 seer Mitsubishi units are revolutionary.

ZihuatanejoMan said:

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Basically this is a deer/ranch cabin when we are working. I could run 240v if really needed but I would rather use the 120v already available since it won't be running all the time.

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I will be doing the exact same with m cabin

Ribeye-Rare said:

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ZihuatanejoMan said:

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Basically this is a deer/ranch cabin when we are working. I could run 240v if really needed but I would rather use the 120v already available since it won't be running all the time.

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I'll run this alternative idea in from out in left field -- To keep things super simple, cut a couple of 14" x 14" holes in the roof of the container and install (2) 15,000 BTU RV-Style 120 volt units (self-contained -- no lines to hook up) and call it a day. Each unit will pull between 15-20 amps.

As for BTU / sq foot, I'd rather have too much capacity in the Texas heat than risk sweating my balls off.

Just a thought ...

EDIT: I realize the roof isn't flat, but corrugated. But you could rig up some spacers to span the low points in order to seal.

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Hard pass on that.

Plus a mini split requires a singlr 1.5" hole through the wall.

Yeah, my container is completely sealed. No holes at all. The front wall is set in at 6' with a front door, window unit and window. The reason I did it that way was to keep the illegals from destroying it. Thankfully we don't have that problem much anymore but would like to keep it as is. Last thing I want is to create a place for moisture, insects and rodents to enter.

Yesterday said:

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The problem we faced in our cabin was that it took forever to initially cool when we came out in the summer. So if you show up at 9pm don't plan on going to bed until midnight as the cabin has to go from 102* to 72(or whatever you prefer).

We went to a bigger mini split and then an extra window unit. That baby cools down quick and gets super cold which is nice when you've been working outside.

So go bigger!

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You probably don't have WiFi at the deer camp but if WiFi or cellular modem is available you can use a device from Cielo to turn on the unit remotely. We have a lake cabin with Mitsubishi mini split system and it works great. It will also tell you the internal temperature remotely. We turn it on a few hours before we get there. Basically you communicate with it remotely and it translates commands for the mini split. The mini split indoor unit has to be in the same room and line of sight since it operates like the remote control handheld unit.

I have a 300 sq/ft workshop (10x30). One ten by ten end of it is an office with computer, sheet rock walls…. All the fancy stuff. I installed a 9000 btu mini split from ecomfort about 6 years ago. I was gone 3 months last summer and for some reason I slid the office door closed which I usually keep open. When I got home in early September, every thing in the room was covered with white fluffy mold. So heed the warnings above about sizing it to your space.