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Thread: Anybody installed a mini split system?

  1. #1
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    Default Anybody installed a mini split system?

    Iím pretty deep into this rabbit hole. Lots of youtube stuff.

    The Mr. Cool let you diy with precharged lines. But I donít have a place to coil extra line length. And I think it looks carpy.

    Sizing the lines, flaring the copper, pressure testing, or vacuum testing all seem pretty do able.

    Adding or removing refrigerant by weight is getting past my wanting to diy it place.

    On the precharged units (not lines), I wonder if they have an allowance for shortening the lines? I understand that lengthening them may require more refrigerant. But they seem to have reservoirs. Some shortening may be ok. Does anyone know?

  2. #2
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    Default Re: Anybody installed a mini split system?

    Sorry. I hire people to do some things and that was one of them. I'm thoroughly satisfied with the results.
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  3. #3
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    Default Re: Anybody installed a mini split system?

    Absolutely no idea, despite my best efforts, to know what the hell you are talking about.

  4. #4
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    Default Re: Anybody installed a mini split system?

    my son in law installed mine w his brother a certified guy looking it over. First week the circuit board failed and was replaced under warranty. Surge protectors are important and I have one on my main panel so who knows there. Been fine for two years then it recently stopped working bbecause of a temp sensor failure that I have yet to fix. I got a something Aire from Home Depot. It wasn’t the cheapest but it wasn’t the more expensive ones. Find a cover for the extra hose if it bothers you. I’ll look up the manufacturer later. grilling right now.

  5. #5
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    Default Re: Anybody installed a mini split system?

    Quote Originally Posted by lupussonic View Post
    Absolutely no idea, despite my best efforts, to know what the hell you are talking about.
    Air conditioning system where the compressor is outside and cooolant goes through a small bundle of pipes to an exchanger in the house instead of a huge course of insulated tubes transporting cold air. It’s quieter than central air. Possibly more efficient but not sure.

  6. #6
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    Default Re: Anybody installed a mini split system?

    I’ve done it. But I had a bit of help at the end. A client of mine was upgrading his heat pumps as part of a big addition I was trimming out. His heat pump company was removing a 18k BTU and a 24k BTU exterior unit and replacing it with a 60k BTU unit. He asked me if I was interested in the old units as he didn’t want the annoyance of selling them on Craigslist. He said I could have them for free. One was 2 years old and the other 3. They cost about $4,500 new. Fujitsus.
    I brought them home but couldn’t find anyone to install them. Even the company that had originally installed them and had removed them for my client. I tried to buy the indoor units at the plumbing supply store but they wouldn’t sell to me without a refrigeration certificate. But an online store was happy to sell them and they were on my porch two days later. I mounted the two outdoor units and the five indoor units and ran all the line sets between them. And here is where I got lucky - I asked the foreman of the crew doing the work at my clients if he did any work on the side. His company had already declined so there was no conflict. He said he only worked for some people but agreed to help me. He came on a Sunday and we worked together the whole day. He flared all the copper lines and made all the connections inside and out. Then he pressure tested the system, pulled the deep vacuum then filled the system with refrigerant. He charged me $750, I paid in cash and gave him an extra couple of hundred. So I got about $20,000 worth of a/c and heat for about $5,000

    I've watched all the Youtube videos, the specialized equipment would be a few hundred for cheap grade stuff. Pro grade would be much more. I felt very lucky Ben helped me out. We have a 7k BTU unit in each of the three bedrooms upstairs and downstairs we have a 9k BTU and a 12k BTU. They cool the house amazingly well for the few weeks that we need it to and cost about a third as much as the window ratters we used to use. In the winter they give some individual control over the temperature in the bedrooms as our oil fired steam heat system has just one zone for the whole house.
    Last edited by StevenBauer; 07-17-2022 at 05:20 PM.

  7. #7
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    Default Re: Anybody installed a mini split system?

    Quote Originally Posted by lupussonic;[URL="tel:6696299"
    6696299[/URL]]Absolutely no idea, despite my best efforts, to know what the hell you are talking about.
    It’s and air conditioner. One of these. I’ve read two installation manuals from different manufacturers and they both state how long the line can be, how to add if longer, but nothing on minimum. Though forum folk think 10 feet.

    If gomer messes it up, bad things happen to the compressor.

    92213D4B-4F44-4EAB-A349-A924FE3DBAC3.jpg

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    Default Re: Anybody installed a mini split system?

    That’s my experience Steve. Nobody wants to deal with diy and the ac industry is a bit of a racket. Can’t say I blame them but I’d think there would be an enterprising ac tech who goes around doing stuff on the side.

  9. #9
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    Default Re: Anybody installed a mini split system?

    It's a heater too.
    That's what my 3 are used for 99 percent of the time.

  10. #10
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    Default Re: Anybody installed a mini split system?

    Quote Originally Posted by wizbang 13 View Post
    It's a heater too.
    That's what my 3 are used for 99 percent of the time.
    Got it! In this part of the world they are called heat pumps.
    There is nothing quite as permanent as a good temporary repair.

  11. #11
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    Default Re: Anybody installed a mini split system?

    Quote Originally Posted by bluedog225 View Post
    It’s and air conditioner. One of these. I’ve read two installation manuals from different manufacturers and they both state how long the line can be, how to add if longer, but nothing on minimum. Though forum folk think 10 feet.

    If gomer messes it up, bad things happen to the compressor.

    92213D4B-4F44-4EAB-A349-A924FE3DBAC3.jpg
    I had three of these installed in my house three years ago. Best money I ever spent. Heat in the winter and air in the summer. The air is on right now and feels great.
    There can be as such as 100' between the indoor and outdoor units.
    All three compressors are outside under a deck where they are out of sight.
    I was born on a wooden boat that I built myself.
    Skiing is the next best thing to having wings.

  12. #12
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    Default Re: Anybody installed a mini split system?

    This.

    Quote Originally Posted by lupussonic View Post
    Absolutely no idea, despite my best efforts, to know what the hell you are talking about.

  13. #13
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    Default Re: Anybody installed a mini split system?

    They are (or can be) extremely efficient. Our Mitsubishi claims 33 SEER. They are also extremely quiet, both inside and out. I've installed two of them. Even on a pre-charged one, you need equipment and know-how to do it right. First, the pre-flared (but not charged) lines were terrible. I had to cut the flares off and redo them. Mini splits operate under very high pressure, as much as 600 PSI, so the flares need to be perfect. You need a proper flaring tool. Once everything is all hooked up, you need to purge air and especially moisture out of the lines, and then pressure test them. vacuum testing alone is not enough. What doesn't leak under vacuum may leak under pressure. Normally, nitrogen is used, so you need a tank of nitrogen and the proper regulator. Ideally, you should pressurize to at least 500 PSI, and leave it for 24 hours. It can't drop at all. Then, you need to vacuum the system down, way down. I use a micron gauge, as the vacuum gauges on cheap HVAC gauges don't show much. Once it's vacuumed down, then you open the valves, releasing the refrigerant into the system. There's a special set-up to do this with a special tool to remove and replace the schrader valve without opening the system.

    As you can see, there is an investment in tools. I bought them because I currently have three units on our property, and will eventually install a fourth one in my shop. HVAC contractors around here tend to take short-cuts, and also want a lot of money to do the work. You might be able to do 90% of the install, then hire an HVAC guy to do the pressure testing and vacuuming, but a lot of guys aren't willing to do that.

  14. #14
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    Default Re: Anybody installed a mini split system?

    Quote Originally Posted by lupussonic View Post
    Absolutely no idea, despite my best efforts, to know what the hell you are talking about.
    I get the "Huh?"

    Air to air heat pumps. They can both heat & cool a house surprisingly efficiently. I had heard the term "mini-split" before so I understood.
    "If it ain't broke, you're not trying." - Red Green

  15. #15
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    Default Re: Anybody installed a mini split system?

    Quote Originally Posted by MushCreek View Post
    They are (or can be) extremely efficient. Our Mitsubishi claims 33 SEER. They are also extremely quiet, both inside and out. I've installed two of them. Even on a pre-charged one, you need equipment and know-how to do it right. First, the pre-flared (but not charged) lines were terrible. I had to cut the flares off and redo them. Mini splits operate under very high pressure, as much as 600 PSI, so the flares need to be perfect. You need a proper flaring tool. Once everything is all hooked up, you need to purge air and especially moisture out of the lines, and then pressure test them. vacuum testing alone is not enough. What doesn't leak under vacuum may leak under pressure. Normally, nitrogen is used, so you need a tank of nitrogen and the proper regulator. Ideally, you should pressurize to at least 500 PSI, and leave it for 24 hours. It can't drop at all. Then, you need to vacuum the system down, way down. I use a micron gauge, as the vacuum gauges on cheap HVAC gauges don't show much. Once it's vacuumed down, then you open the valves, releasing the refrigerant into the system. There's a special set-up to do this with a special tool to remove and replace the schrader valve without opening the system.

    As you can see, there is an investment in tools. I bought them because I currently have three units on our property, and will eventually install a fourth one in my shop. HVAC contractors around here tend to take short-cuts, and also want a lot of money to do the work. You might be able to do 90% of the install, then hire an HVAC guy to do the pressure testing and vacuuming, but a lot of guys aren't willing to do that.
    I've never understood why plumbers & HVAC folks don't use double flares when dealing with high pressure. It's required on auto brake lines (thousands of PSI) & so the tools are readily & fairly inexpensively available. Takes a minute longer, but makes a vastly better connection.
    "If it ain't broke, you're not trying." - Red Green

  16. #16
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    Default Re: Anybody installed a mini split system?

    We paid someone to do it. I must admit it's worked pretty well.

    Mickey Lake
    'A disciple of the Norse god of aesthetically pleasing boats, Johan Anker'

  17. #17
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    Default Re: Anybody installed a mini split system?

    Quote Originally Posted by MushCreek;[URL="tel:6696442"
    6696442[/URL]]They are (or can be) extremely efficient. Our Mitsubishi claims 33 SEER. They are also extremely quiet, both inside and out. I've installed two of them. Even on a pre-charged one, you need equipment and know-how to do it right. First, the pre-flared (but not charged) lines were terrible. I had to cut the flares off and redo them. Mini splits operate under very high pressure, as much as 600 PSI, so the flares need to be perfect. You need a proper flaring tool. Once everything is all hooked up, you need to purge air and especially moisture out of the lines, and then pressure test them. vacuum testing alone is not enough. What doesn't leak under vacuum may leak under pressure. Normally, nitrogen is used, so you need a tank of nitrogen and the proper regulator. Ideally, you should pressurize to at least 500 PSI, and leave it for 24 hours. It can't drop at all. Then, you need to vacuum the system down, way down. I use a micron gauge, as the vacuum gauges on cheap HVAC gauges don't show much. Once it's vacuumed down, then you open the valves, releasing the refrigerant into the system. There's a special set-up to do this with a special tool to remove and replace the schrader valve without opening the system.

    As you can see, there is an investment in tools. I bought them because I currently have three units on our property, and will eventually install a fourth one in my shop. HVAC contractors around here tend to take short-cuts, and also want a lot of money to do the work. You might be able to do 90% of the install, then hire an HVAC guy to do the pressure testing and vacuuming, but a lot of guys aren't willing to do that.

    This is what I am seeing. About $500 in equipment. Be helpful to be able to rent the nitrogen set up.

    One of the many benefits is no surge on these units. Therefore save on the battery inverter cost.

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