DIY patent

Our Newly Patented MRCOOL DIY

  • October 27, 2021
  • By MR COOL

MRCOOL is happy to announce that on 21 September 2021 it received Patent No. 11,125,479 from the United States Patent and Trademark Office. This ‘Apparatus and process for amateur HVAC installation’ patent makes the MRCOOL DIY the only ductless mini-split heat pump on the market with technology patented and verified to ease installation for nonprofessionals.

While the competition can only claim to be do-it-yourself worthy, our DIY patent proves that our technology really is.

Why Our DIY is Superior

What does the MRCOOL DIY have patented that other mini-splits just don’t?

Our Quick Connect lines are the star of the show. These lines and their integration into the overall design mean that this mini-split can be installed without the necessity of in-field vacuuming or charging. Plus, they can be easily connected without cutting or brazing. In short, this patented technology means that anyone can hook up the refrigerant lines on the MRCOOL DIY without special tools, training, or industry-only know-how.

This innovative approach to HVAC is what has allowed MRCOOL to grow into a space once dominated by giant, old money corporations. It is our conviction that tech disruptors like our patented DIY design, and others on the horizon, will change the face of this industry in a much quicker timeframe than the experts believe.

Do you have questions about the MRCOOL DIY patent and what that means for the future of our market? Reach out to us at 270-366-0457. Looking for a MRCOOL partner near you? You can find that here.


40 thoughts on “Our Newly Patented MRCOOL DIY”

  1. I just installed the MRCOOL MDU0180124036 and air handler. The concept is fantastic, I installed in a mobile home so it was a bit more challenging. I really like it this first night of operation. Although, I dread the day I will have to charge the thing because the charging connections are situated so it will be very difficult to get my hoses on. A few other things I noted. The King valves are so close to the bulkhead that connecting the line sets is more difficult than need be. Along with that, it is very difficult to get the insulation around the “Low side” or gas tube on the A-coil. A little more clearance would make installation a little more forgiving and not so frustrating. The refrigerant line connections on the condenser are inside the front right panel and face downward. I mounted the condenser on slab next to the house. This meant the tubing had to make a 90′ bend from side to an immediate 90′ bend up, not real conducive for the “non-kink” line set. That said, the install was reasonably quick and easy. The no braze “no-vac” lines had me. I can no longer see the flame to braze correctly. That along with the 10 year warranty sold me.

  2. I have just finished the installation of a Mr Cool DIY 18,000 BTU Energy Star Ductless Mini Split Unit. The unit is the 3rd Mini-split unit I have installed in my home over the last 4 years. The first two units were each a different brand and size, the first a 24K BTU unit (a noisey unit) , the second 9K BTU in our garage (very quiet), and now for our kitchen/dinningroom/office area our new Mr. Cool 18K BTU unit. (The quietest of all) The unit was a joy to install. Your company provided superior direction manuals that were very detailed and yet easy to understand. All required part were include with a few spare items included as well. Your company’s newly patented refrigerant lines and fittings were easy to install, and all fittings sealed perfectly on the first try. I do have Torque wrenches from installation requirements for former mini-split units I’ve installed, so final steps were easily done as per your installation manual. I recognize though that for DIY home owners, your new fittings should seal well for those who do not have the torque wrenches that are recommended. Your new fittings are such an improvement for refrigerant lines. One note on your installation instructions though: I would inform installers that the new fittings do require more turns that the traditional flared fitting to get to the “snug point”. Your new fittings really seat all the way on with no visible thread to be seen as the “snug point” is reached. (old flared fittings reach that snug point much more quickly from my experience) Thus I would suggest that you inform the installer that the fitting may take a number of turns to reach that snug point, before the final wrench torque tightening of just a few degrees of turn is completed. Mr. Cool has developed a very fine product, and I hope that word of mouth will continue to provide strong sales for you company in the years to come. Congratulations to your design teams for: innovative engineering, superior shipping and packaging expertise, finely written instructions and great customer service. I can only praise you all for running such a fine organization and backing your products with the home owner in mind.

    1. Thank you very much for this thoughtful review! We’re ecstatic to hear that you’re enjoying our unit, and we’re incredibly grateful for your feedback. Once again, thank you!

  3. Congratulations on the patent. I installed a 48K DIT unit for my Dad in mid northern Ohio and it was not very difficult. It worked great through the summer and is now providing heat. Even more heat now as I just installed the 15KW strip heater, although the heat pump alone had been doing fine so far. One question that I am not having much luck getting an answer to, the airhandler control board has a red and a green LED and their operation is not described in any literature I have been able to download so far. Can some help please?

    1. The red light is a power indicator. The green light is a running indicator. If the red light is on, the indoor unit main board is running. If the green light is on, the indoor fan is on. If the green light is flashing, this is indicative of a system failure.

  4. Please consider pairing the Universal condenser with a DIY mini split air handler. I am sure many people in cold climates would upgrade or purchase the higher rated Universal condenser as a single zone unit. It is great both series come with the quick connect line sets. I installed the DIY 24k single zone mini split and it was easy to install.

  5. This is a great system as long as the larger cylinder fitting is secured tightly from the factory.

    I installed a 24k DIY system last April and while the leak tests showed no bubbles at the 4 fittings during install, come colder weather and using heat mode my system stopped working after a couple weeks. Hooking a gauge up to the service port showed no pressure, the refrigerant had all leaked out.

    When inspecting and checking the tightness of the line connections I found that the larger brass cylinder attached to one of the king valves on the outdoor unit wasn’t tight. Also, one further up the line which has the black sticky “sound deadening” pads wrapped around them during install was loose and leaked.

    The part of theses quick connects that the end user screws together were all tight and not leaking.

    I had to have the system evacuated and recharged with the 5.18 lbs of refrigerant which wasn’t that cheap to have someone licensed to come out and do that.

    I’d suggest adding a step in the install manual to check these pre-installed fittings for tightness before connecting the line set to them.

      1. I recently completed installation of the DIY-18-HP unit and also noticed that the line adapters were not very tight. Unfortunately, I did not read the step in the manual that specifies to “NOTE: Ensure the adapters attached to the outdoor valves have been tightened properly before attempting to connect the line set.” I did verify that there were no leaks, however, I’m concerned about a leak developing in the future. Should I slightly loosen the piping connections and then tighten the adapters, then re-tighten the line set?

  6. So engineer 775 on your ad says Mr Cool is solar compatible. I have purchased 3 Mr Cool mini splits and the 3 ton and 5 ton universal’s can you explain that statement please. Thank you, Brian.

    1. We do not have any guidance, such as manuals, on how to install the DIY with solar power. If you’d like, you can give us a call at 270-366-0457, or watch the YouTube videos of people who have performed similar installations, such as Engineer775.

  7. i would like to install your system for a ducted installation. We are renovatating a three story 980sq foot townhouse. The unit currently has no duct work. I’m willing to add it. is this something i can do myself, or can I only diy splits? i would need help sizing the ductwork. thanks.

    please only use my first name if this is posted

    1. We do not recommend that you install ductwork on your own. That can be an extremely complicated process, and you will likely need the assistance of an HVAC professional. If you are interested in the Universal, you will need an HVAC professional to install it for you if you’re having it traditionally installed. If you’re using the pre-charged line sets, you can do it without a professional’s assistance and still be within the terms of the warranty.

  8. What’s the longest permitted run for the electrical lines and coolant hoses for your DIY units? I live in a 4th floor co-op apartment; unless I can get Board permission to hang the outside unit on an exterior wall at my floor level level, my only alternative is running it all exterior to the roof, 18-23’ up from 2 feet below my ceiling. Thinking of this for either your smallest DIY or possibly your two zone DIY unit.


    1. The DIY can have a maximum line set run of 75′. The longest individual line set that we offer is 25′, so if you need a line set longer than that, you will need to link two line sets together using our Quick Connect coupler kits. These kits and additional line sets for the DIY can be found at any of our retailers.

      1. What is the shortest recharged line set you offer? If I order the 25ft kit thru Costco…could I swap it for a shorter length?

  9. I would like to get the diy 3rd Gen MI split system that I ordered from home depot. My order went through and a day later it was back ordered. Now home depot’s website says that it is discontinued. I have called and left multiple messages with Mr cool support and I am now getting the silent treatment. I am rather frustrated. I’m starting to wonder if I should continue to persue getting one of these systems if this is what customer service is going to be like..

    1. We apologize greatly for this. Would you mind sending me a reliable contact number so that someone from our service team can reach out? Your personal information will not be made public.

  10. I installed a DIY mini split in June. I believe it was shipped with low refrigerant as the inside unit began icing over on day 1. I have been trying to contact Cool for 3 weeks and have received no response. I’ ve called and left messages, requested callbacks, and submitted email requests. So much for warranty and customer service.

    1. We apologize greatly for this. Would you mind providing your contact information so that someone can reach out? Your information will not be made public.

  11. I luv ur unit but I just wish that we as costumer would b able to choose the length of lines. Mine is to long so I had to wrapped it up behind the compressor. Can u give us an obtion ?

    1. We offer pre-charged line sets for the DIY ductless mini-split in lengths of 16′ and 25′. They can be purchased from any of our retailers.

  12. I am planning to install 12K DIY split unit in my basement. The ceiling hight is 7’8”
    Is it okay to do it?
    Are there any precautions

  13. We are installing the 1800btu. The manual says to open the king valves. Our unit doesn’t appear to have a king valve. Where could it be hiding?

    1. On a multi-zone unit, the king valves are typically above the valves that you link the line set to. You may want to give us a call at 270-366-0457.

    2. Phil any chance you can tell me how this resolved? I just realized my newly installed unit doesnt have king valves either and I’m hesitant to turn it on without knowing what the deal is! Memorial Day weekend they won’t be open again til Tuesday! Thank you in advance if you do happen to see this and help me out!!

  14. I bought 18000 BTU wall unit before two years. Air handler shows error code E1. I watched YouTube video to fix. I did as per video. Still same problem. Can I buy new air handler to replace defective one?

  15. (Please do not post my email)Thanks!
    I am interested in a package heat pump,3ton.
    Do your units have a scroll compressor,and variable speed compressor (VFD).
    What is the highest SEER package heat pumps that you make?
    What is your warranty,and what is fully covered,parts and labor.
    Thanks for your valuable time and efforts on this matter.

    1. These units do have scroll compressors. The blower motor is multi-speed. The highest efficiency package systems we have are geothermal, but that is a much larger project than a typical package system. The best SEER for a typical package heat pump is 14. If registered, the Signature package heat pump has a 10 year parts warranty.

  16. I’m in the process of installing a dual zone 9k/12k mini split. I see no king valves. They’re certainly not where the manual shield them. Where are they????

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Are you a MRCOOL reseller or installer?
For questions about becoming a reseller or representative call 270-366-0457.

Sign Up