How to Install a Ductless Mini-Split Air Conditioner | This Old House

This Old House plumbing and heating expert Richard Trethewey explains how to install a mini-split air conditioner. (See below for a shopping list and tools.)

Richard traveled to Tampa, Florida to help a homeowner find a cooling solution for his garage. The homeowner used the garage as a workshop in the summer months, but said that it was too hot and humid in there to work comfortably. To solve the problem, Richard and local expert David Zimmerman installed a "mini-split" air conditioner. The system uses no ductwork. Instead, an air-handler unit is mounted inside on a wall, and the condenser unit is mounted outside.

Shopping List for How to Install a Mini-Split Air Conditioner:

Tools for How to Install a Mini-Split Air Conditioner:

It was Installed by David Zimmerman, Zimmerman's Air Conditioning & Heating, Inc.

Additional assistance was provided by Ryan Hansen, electrician, Hansen Electric, Inc.

About Ask This Old House TV:
Homeowners have a virtual truckload of questions for us on smaller projects, and we're ready to answer. Ask This Old House solves the steady stream of home improvement problems faced by our viewers—and we make house calls! Ask This Old House features some familiar faces from This Old House, including Kevin O'Connor, general contractor Tom Silva, plumbing and heating expert Richard Trethewey, and landscape contractor Roger Cook.

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How to Install a Ductless Mini-Split Air Conditioner | This Old House

[Bangbangbigelow]

Excellent walkthrough. The tools, time invested and know how demonstrated have made me confident enough to hire a professional

[outlawgaming]

I grew up watching This Old House. I used to watch it as a kid to pass the time, as a young teenager I found myself using knowledge and techniques from this show. As an adult, I now thoroughly enjoy watching these gentlemen repair or install just about anything. I hope this show is on forever and I intend to leave PBS in my will.

[TokyoCraftsman]

I install these in Japan, have for a while. We don't test with the nitrogen, instead we make the connections and with the valves still closed on the compressor unit, we pull a vacuum with the vacuum pump, let it pump down for a while, and watch the gauges to see if it holds vacuum, it if does you are good to go, no need to lug around a nitrogen bottle and regulator. Nothing wrong with the nitrogen bottle pressure test, just a different way to do it. One more thing, once the lines are attached and you have pulled a vacuum in them, they are ready for the coolant. kind of one step less this way.
These systems are great, really like them.
Cheers!

[aaronsoto]

This guy made that complete installation look soooo probably installed like 100 of these.

[Vara]

I learned something with this clip. I learned to have professionals install my AC units, lol.

[annette]

I have enjoyed watching This Old House for many years. Your experts make it look so simple, although I know it isn't. I am looking for a company in South Florida to install this in my home. It has been so difficult to find a reputable company, so send some prayers my way.

[WandereringFamily]

0:00 - Ooh, I'd love to do this for my garage!
0:30 - Yep, this looks doable, maybe next weekend?
2:00 - Hmm, this might be a big job ...
2:40 - Oh, I would have probably messed that up and crimped that line.
3:10 - "Flaring tool?" What is that?
4:40 - Testing for leaks with nitrogen? Who are they kidding? I can't do this!
5:30 - Yep, this is why you hire a professional to do this job. Not even remotely tempted to try this myself any more.

[dutchman]

I really love to watch the differences concerning installing this unit between the USA and here in Holland. We are not allowed to use the flare nuts. So we remove the flare connection from the inner unit, and braze with silver solder the copper pipes directly on the inner unit. The communication cable between inner and outer unit must be shielded. For the electrical supply, we must use covered cable (not the 3 seperate cores). The safety switch must be from PVC . Metal junction boxes or switches are not allowed. I like the concrete foundation where the outer units is mounted on. But because of laws here, we are not allowed to carry stuff more than 25 kilos (approx 50 pounds), so we mount the unit on a console on the wall, or (when installed on a roof) recycled plastic beams. Oh, BTW, we use a 300 mm (approx 1 foot) 60mm (2, 5") hollow drill saw, to cut the hole from inside to outside in one move. Greets from the Netherlands (in Europe).

[bettyboop]

After watching a couple of TOH videos about mini-split systems I now know why installation costs are so high. That is a lot of work putting in one of these systems and what it means to have qualified installers. Thank you.

[davidburnham]

I helped our HVAC guy install one today. A more complicated configuration than this but still very straightforward and kind of fun.

[machfive]

One of the best ductless mini split installation videos on the net.

[vikashdutt]

Gives a very fair idea of how easily a split a/c can be installed, great job guys.

[alecgaston]

I’ve learned over the years, there’s this stuff called Nylog . It’s pretty much a liquid gasket that’s compatible with 410A and r22 . It comes in handy when making your flare connections and I will stand by it

[jbills]

Thumbs up this unit saved our asses in Afghanistan..one day it was 108 outside turned this puppy all the way down and I found my camel pack in my room slushy. It also has a dry (dehumidifier) setting...in the winter it snowed in the morning sun evaporated snow lead to humidity in the morning. Perfect for garage storage. POG life

[jeanducheamps]

Always a good thing to keep the car cool and comfy

[RogerCoville]

First off - I'm a huge TOH fan. I subscribe to the magazine and watch the PBS reruns too often. I was disappointed that they never even mentioned the 220 volt disconnect that just "appears" on the outside wall. Please keep looking for many other more complete system installs on youtube. The DIY guys go way deeper on all steps.

[billleonard]

Nice video. Thanks. We have a mini-split in my home office space and we’re considering one for a fixed mobile home we have down south.

[imaslowlerner]

Those units are great. I'm in Egypt and had one installed last year, easy to install. So I said to myself that I'm going to get one when I return to the USA. Well the cost in Egypt with installation cost me about $450 US dollars. Just check out the price online in the USA and that's for the unit only, do it yourself. Keep your filter clean.

[sbukosky]

These guys are in oil burner country so are very familiar with flare connections. For those that are not, the installation manual says to put a little oil on the flare surfaces and has torque specifications. Special torque wrenches are sold at Mitsubishi distributors. Don't put the insulation over the connections until leak checked!

I don't recall seeing the extremely important step of evacuation of the lineset and evaporator. That's how you get that nitrogen out otherwise it will be a big bubble of gas going through the system and will reduce cooling capacity and may cause other problems.

[qaz]

My dad wanted to get a small portable AC and I said that now adays they sell real split air conditioners for under 1000 bucks and that I would gladly come and install it with him. This video confirms what I imagined what the install would be like just looking at the unit. If we get the electricity ready in advance Im sure we can start after lunch and be ready by dinner time.