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Seriously, _how_ do you buy hvac equipment for diy?

23992134929 | Posted in General Questions on

I’ve read, and that’s a great (if outdated) article on WHAT to buy, but not how to buy. I’ve called a few supply houses in my area and they’ve both told me that they only sell to licensed contractors.

Do I need to keep calling around? Do I need to call Mitsubishi directly? Am I forced to buy online from a retailer like hvacdirect or amazon? I’m really hoping to avoid the big box stores for this.

What accessories do I need? Should I buy the indoor unit and outdoor unit as a set, or separately?

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  1. mikeferro | | #1

    The online retailer sells name brand equipment to anyone

  2. Expert Member
    Akos | | #3

    Instead of full DIY, you best bet is to get an HVAC contractor to quote only supplying the equipment and either install/commission or just commission. Everything else (drains, power feed, mounting brackets, mounting indoor unit, ducting) is done by someone else.

    More costly than an internet buy but this gets you full manufacturer warrantee and it is much lower cost than a full install.

  3. paul_wiedefeld | | #4

    Is it worth your time? Do you expect to save money installing yourself or is it more of a hobby? Is the warranty important to you?

    1. 23992134929 | | #5

      My area has the highest cost in the trades in the country right now, so if you can even get a contractor to call you back, you're usually looking at months of waiting and prices that are prohibitive.

      Plus I don't trust them with the penetrations.

      1. paul_wiedefeld | | #6

        Can you beat $200/work hour? HVAC technicians make substantially less than $400k/year and you’ll be substantially less productive than someone who does this full time with professional tools while taking on all the risk. Plus the same supply chain constraints apply to you, probably to a greater extent.

        Not meant to discourage, I do plenty of things poorly a profession could do in their sleep.

      2. exeric | | #10

        I think you've clearly given valid reasons for DIYing an HVAC system. It isn't rocket science as much as professional HVAC men would like you to think that. I am not a professional HVAC installer, but I successfully did my own installation. It's not that hard. The most important thing is to do your homework. That includes an honest quantitative assessment of what tonnage HVAC you will need for your installation. On my installation I used Cool Calc to calculate that. It isn't an expensive program. There are others that will work also.

        Next, you should understand what limitations your home imposes on the installation. That is, how many heads you will need and if you want to have each head direct fed from a compressor or have multiple heads from one compressor. This is where it gets complicated. You don't want to locate heads where the air will be blowing directly on individuals sitting on chairs, couches, or lying on a bed. Diffuse air movement is what you want. If there is a natural area that people use to walk between rooms then that is where you want the heads to be blowing air because normally chairs, couches etc. will not be located in those areas. Also, just like people have natural corridors for movement within a home, air can also use those same corridors. This is very important and I seldom see it mentioned by professional HVAC people. If you are smart, (and also lucky), you can use those natural corridors to move air to reduce the number of heads required for a given area. In my own home, which is only 1100 sf, I have such a natural corridor and was able to use just a single compressor and dedicated head and have very consistent temperatures throughout the house. There is no area that I spend a lot of time in that is drafty. You just have to do your homework.

        The last thing is that there are mini splits, such as Mr. Cool, that are made for DIYers. They are pre-charged with "freon" and come with quick disconnects. No vacuuming or flaring is required. The limitation is that they come with preset lengths of line that you have to be able to work with. I found it not to be a problem as long as you think ahead. My Mr. Cool has worked well now for almost one full year of heating and cooling with no problems. The thermostat is a little finicky and not that accurate, but once you get to know its "quirks and features" its not a problem. I'm able to keep the house at the temperature I desire. I estimate I paid $2000 all in, including the concrete pad I installed for the compressor and the associated tools and supplies for that. The unit is meant to be DIYed and has a warranty that accepts a DIY installation. The units that require a vacuum and flaring connections don't come with a warranty for DIY. I found mine to be excellent value for money. If you live in an area that regularly gets below 0 degrees F a Mr. Cool might not be the best choice though. Mr. Cools can be found at most 0f the big box stores and online.

        1. Tim_O | | #11

          I thought you would still want to vacuum out the lines before filling with the precharged freon? Maybe the Mr. Cool system has a process to keep moisture out of the lines that the others don't.

          1. exeric | | #13

            Both the DIY and non-DIY Mr. Cools come pre charged with Freon. My understanding is that the DIYs keep the charge in the line set. Those line sets are pre-vacuumed and have quick disconnects on each end that keeps the freon in and moisture out. When you connect the line set on each end it releases the freon into both the compressor and the air handler.

            The non-DIY units keep the freon inside the compressor instead of the line sets, if I understand correctly. The line sets are open on each end. After it is connected to the compressor and air handler it has to be vacuumed, both to remove moisture and to leak check it. Then a valve is opened at the compressor that releases the freon to the system.

  4. big__o | | #7

    Any online retailer will sell to you. You won't have any kind of warranty but the two thirds you save not hitting a contractor is your self warranty

  5. Tim_O | | #8

    Just a side note on DIY for refrigerant side of things - autozone has a vacuum pump and A/C gauges in their loaner tool selection. You'll need an adaptor for R410A, cheap on amazon. As mentioned above, maybe you'll want someone to commission the equipment. Not sure how easy it is to get refrigerant certification or the equipment to nitrogen purge the lines... I just put a vacuum on the system for a long time and closed the system to see if it held for many hours or even overnight. I've done two cars and a mini split this way.

    1. Expert Member
      BILL WICHERS | | #9

      You have to take a short test to get the certification from the EPA that will let you buy refrigerant. You then need to go to a supply house with the certificate and have them set you up in their system before they will sell to you.

      The big question is WHY do this though? You can save most of the labor money by just physically installing the equipment yourself, then have a contractor come charge it. There is more to putting in a proper charge than just throwing on some gauges, since the pressures are temperature dependent. The quality of the vacuum you pull when you start also contributes to the longevity of the equipment, so you need to do it right. I'd leave charging the system to a pro if you haven't ever done the work before.


      1. DC_Contrarian_ | | #12

        Right now around here all the trades are so backed up it's hard to get anyone to even return a call, unless you have an existing relationship or a friend in the business you're not going to get someone with a license to take on a job like that. And in DC, all HVAC equipment has to be installed by a licensed professional (or at least under their supervision).

    2. Deleted | | #14


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