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Pre-Charged Line Sets Are For Real, Right?

pre-charged line sets

Pre-charged line sets aren’t exactly a new innovation in the HVAC industry, but they’re not exactly widespread either. When we tell people our MRCOOL DIY line sets do not need to be vacuumed down, plenty of installers out there, professional or otherwise, just don’t believe it. But, hey, don’t take my word for it!

Pre-Charged Line Sets Are the Real Deal

A picture is worth a thousand words, so a YouTube video has to be worth like a novel or something. Anyway, check out the comments in our 2nd-generation DIY install video and you’ll find plenty of folks who don’t quite believe. If you don’t want to take the time, then I’ll sum up the highlights for you.

No vacuum? Are you kidding me?” – St2288

How is that possible?” – E Money

Don’t you have to use a vacuum pump or purge the lines?” – Juan Silva

Wait a sec, no purge of the line-set or vacuuming them down first?” – Butchtropic

Yeah, there are a few skeptics.

So, Are Pre-Charged Line Sets Real or What?

Yes! For the last time, yes!

We here at MRCOOL did not invent pre-charged line sets. They’ve been around for years, but were mainly confined to the modular and mobile home market. That might be one reason why so many people have not heard of them. Don’t worry! Pre-charged line set technology proved itself years ago.  Basically, all we’re doing is applying them in an innovative way.

Innovative How?

One or two manufacturers have used a version of pre-charged line sets on ductless mini-split units before, but we are proud to say that no one has taken it as far as we have. The MRCOOL DIY 2nd-generation Ductless Mini-Split Heat Pump is truly cutting edge technology. Our unique approach makes line sets easy and safe to handle. Best of all, any smart homeowner can put one of our DIY units up in a few hours with no specialized tools.

It’s like they’re comfort made simple or something.

237 thoughts on “Pre-Charged Line Sets Are For Real, Right?”

      1. Pre-charged lines do not need to be evacuated. If you have a line that says it needs to be evacuated, it is not one of our pre-charged lines.

      2. Did you buy the Mr Cool “Advantage” series because you saw it was less expensive than the DIY series? The Advantage is substantially less expensive than the DIY because the Advantage does not have the precharged lines and requires purging and charging.

  1. What size wire is required for the DIY 24k btu? The specs state a minimum circuit ampacity of 15a. That would mean 14 gauge wire. My electrician says 12 or even 10 gauge.
    Also can I use a 30 amp disconnect or it has to be 25amp?

    1. There should be a wiring chart in the installation manual on page 17. We would recommend a 12 gauge. Your disconnect should be 25 amp or more.

  2. How long are the line sets included with the 36k BTU? Can the excess line set be rolled up? I have about a 12 foot run from where the indoor unit is to where I will be installing the outdoor unit.

    1. I believe the line sets on that unit are 25 feet. Yes, the excess can be rolled up to look quite neat. That’s what most people do in fact.

      1. MRCOOL had very good product for DYI like me, the only thing MRCOOL did not support is more than 25 feet pre-charged line. I am willing to pay extra for another 25 feet pre-charged with connectors such as air-compressor connector then I can extend the line to 50 feet. My room in in the second floor.

        1. I am successfully to install 50 ft line of Ductless Air Conditioner with different brand name (Pioneer 24K cost ~$1300.00) with extra step by vacuuming the 50ft line and add about ~1 lbs R401a. It is easier than I thought. Total tools and additional material cost me less than $300.00 – System is working excellent. Before decided DYI, I got several quote from local with the price range from $3000.00 – $4000.00, with DYI, it is significantly good saving for retiree.

  3. Is there an option to get longer line sets?
    I want to install the air handler in a remodeled attic, so the distance from the top to the ground is closer to 32 feet. Also is there a maximum height distance that you cannot go beyond?

    1. There is not an option right now for longer line sets. We’ve got some things in the works, and that is a product we hope to roll out eventually. Can you give me some more details about how you want to install the unit?

      1. I am in the same boa as Chuck. My run is close to 40 feet. I’d love to buy a 12k unit but the lack of line options is a deal buster. 🙁
        Any ideas on how to find a reasonable HVAC tech to install?

        1. You can always use Google, of course. I know some people have had luck using Craigslist and Angie’s List.

      2. Same here. I need about 50 feet of lineset to get from the indoor unit to where I can put the outdoor unit. I don’t suppose there is a way to connect two 25 foot lengths? If I can get 50 foot linesets I’d buy three systems.

        1. Unfortunately, there is not. However, that may be possible with the 3rd generation system due sometime in 2019.

          1. Since we’re putting together a list of requests, here are some things that you might want to offer, whether they would be included in the next DIY system, or sold as accessories:

            1. Multi-zone Systems (I’d have bought two three-head DIY systems this year, if they were available, and I still need a two-head DIY system)
            2. Condensate pumps (It’s not always easy to find an all-downhill route for linesets)
            3. Hyper Heat kit (an electric coil kit that plugs into the standard DIY unit to allow operation in colder environments)
            4. Linesets in various lengths

            Thanks!

          2. I just purchased the diy unit and found out I need more than the 25′ line sets. You mentioned above they will be available in 2019. Are they available now? Can I add copper line to make it longer? Is the refrigerant in the outdoor unit or indoor?

          3. On the DIY unit, the lines come charged, so you cannot cut or modify them without professional training and equipment. Unfortunately, the variable-length pre-charged lines are still in product development.

    2. For those of you needing to install the air handler more than 25 feet above ground level, one option you could consider is to wall mount the condensor unit instead of placing it on a pad on the ground. The condensor unit runs very quietly so there should not be bothersome noise or vibration from an exterior wall mounted unit. You just need to get a bracket with adequate clearance from your exterior wall.

  4. I have some suggestions:

    – Smaller capacity! 12k BTUs is super overkill for a bedroom; something around 3000 is more reasonable. All the better if this raises the SEER and HSPF numbers.
    – Short linesets: if I’m going right through a wall, I don’t need 26 feet.
    – A standard wall plug; no hard-wiring!
    – Get the price under $1k

    If you sold units with those features, I’d buy four, like, yesterday.

    1. Thanks, Nate.

      – Interesting idea.
      – The problem there is about manufacturing cost. We’re working on a way to give customers more precharged lineset options, but it’s still very early in development.
      – That could be possible if we made a smaller capacity unit, but none of the current units can be safely plugged into a standard wall socket.
      – Nate, most dealers sell our Advantage units at around $700.

  5. Regarding the 24k btu, the electrical data on the brochure states “max fuse 25amps”. I read this as saying the disconnect must be fused at 25 amps. However, one of the answers to the questions above says ” preferably non fused”. Can you please clarify the requirements ? Does it require just a 25 amp breaker at the panel or the 25 amp breaker at the panel and the 25 amp fused disconnect?

    1. You do not have to have a fused disconnect. You may have a non-breaker disconnect. At the breaker panel, it has to be 25 amps. The outside disconnect is only for servicing the unit.

    1. The pre-charged linesets only come in 25′. You can get a variable length with an Advantage or Oasis unit. They are not DIY, but they are very good units. A 12k should be sufficient for 500 square feet, but you might want to get an 18k just to be sure.

        1. We have DIY ductless mini-split heat pumps and Packaged DIY units. If it doesn’t say DIY in the title, it’s not DIY. Well, not without some specialized tools and training anyway.

  6. Can u cut the pre charge line set and wiegh the 410a back in I had a homeowner call me today and he said he bought one of these units and the line is to long I am licensed tech

    1. Yes, that would be possible. The refrigerant lines with a DIY unit are pre-charged, but other than that they are basic refrigerant lines.

    1. If the unit is installed and then uninstalled correctly, no, you would not have to charge the lines. If errors occur and refrigerant escapes the system, then it would require charging to the appropriate capacity.

      1. Do you guys make a 3 zone system in the DIY? I have a small 2 bedroom cabin approx 800 SF. I’d really like to have an indoor unit in each bedroom and one in the living room that is open to the kitchen.

        1. We do not currently offer a DIY multi-zone unit. For that, I would recommend the Olympus. It will require a contractor to install, as special equipment is necessary. Alternatively, you could install multiple DIY units.

      1. No I’m asking about the range the inverter throttles down to and up to. I’m guessing 18,000 btu and 24,000 btu is the most it puts out during high load but what’s the lowest it puts out when the load is low like during the shoulder seasons?

          1. Thank you very much for this information that’s exactly what I was looking for. Does the hyper heat units have the same range as well for the 18,000 and 24,000 units.

  7. Thanks for the reply last question,is it more efficient to leave the unit on for longer periods of time or is it better to shut it off if I have to leave the house for an hour or so?

    1. Typically, shutting the air conditioning off for short periods to save money doesn’t really work. The only time I do something like that is when I’m going to be away from home for a few days. I also never turn the unit off completely. Dehumidification is an important part of air conditioning, and keeping interior humidity at a reasonable level can help prevent mold growth. Just set the temperature higher than what you would normally comfortable with, but not so high that the unit never kicks on.

      1. So, should unit be shut down in those temps and auxiliary heat take over? Do you have any units designed for lower ambient?

        1. Yes, that would be recommended. Our Oasis Hyper Heat units are designed to operate more effectively at lower temperatures.

  8. I have the DIY 18000 BTU. I have heard there are alot of problems using the smart phone app. I can’t even get the QR code to read without it saying illegal code! What can I do, and when will the app be taken care of so it works? That’s one of the reasons I purchased a Mrcool!

    1. The ‘illegal code’ error message usually display when you scan the wrong area of the box. Give us a call at 270-366-0457, ask for tech, and they’ll walk you through the process.

      1. Did you put the Indoor unit in AP mode? (by holding the led button on the remote for 4secs) I had the same problem when I bought it last year

  9. Any plans in the works for a multi zone DIY unit?

    We have a single level 1100 sf house (26×43), our Split Ac went out and I am
    looking at all possibilities for replacement. The house is open kitchen, living and dining room followed by a hall with 2 small bedroom and one larger master. Ceiling Mounted return vent in hall for central gas heat and ac.

    Wondering if one 24k unit on living room wall opposite the return vent (hall is off living room center and runs down center of house) would work. When needed turn on furnace blower to circulate air through out the house? Could probably wire furnace blower to come on at a set temp in cool mode (with current ac disconnected of course)?

    The price of your unit beats a $4000-6000 split ac install. Bearing the fact in Boise Idaho we need AC only 3-4 months of the year (wife’s View) 2-3weeks in August (my view)

    1. We have had internal discussions about a multi-zone DIY system. However, if we deploy a product like that, it won’t be anytime soon.

      A 24k in the main living area should be sufficient for a lot of your cooling needs. You could then put a 12k or 18k (at most) in the master bedroom. Together, I think those two would be sufficient for your entire house. You could probably wire the blower to act as an improvised cool air circulator, but I don’t think that would be necessary. Proper mini-split placement should meet your needs without having to worry about jury-rigging your heater.

      1. Thanks for the quick reply. Trying to avoid the cost of 2 systems. I keep pondering If one 24K would work for whole house.
        As to the furnace I think all it would be is; disconnecting the control wire to the current outdoor unit. Setting the thermostat to cool position and temp say to x degrees. This will force the blower to come on till the bedroom area reaches x degrees. Distributing cool air to the bedrooms.

        Our duct work is in a crawl space and not in the attic so it stays pretty cool in the summer.
        Returns are insulated and in the attic though. Right now it is 81 outside left windows open last night and blower running no ac on it is a col 72 inside.

        1. A 24k is going to be good for around 1000 square feet. If you wanted one system for the entire house, you may want to move up to a 36k.

    2. Walt, if you haven’t already made a purchase maybe I can shed some light. Your floor plan is exactly like mine, only my sq footage is 1565. I mounted a 24k unit high on the great room wall opposite the hallway and cold air return. The unit does a marvelous job heating and cooling the 700 sq ft great room. In winter, I installed a floor to ceiling curtain to keep the great room heated evenly. Since we don’t heat the back of the house except at rising and retiring, this has saved a lot of burned gas and we now keep the great room at an even 72 deg in winter instead of a drafty 69. Circulating cool air with the gas heater on fan, is a technique we used to cool the house down pre mr cool when afternoon temps dropped. I can see no reason why using this technique would not be a quick and easy way to circulate cool Thru out the house just as the gas furnace would circulate heat

  10. I just installed the 18K DIY unit and love it…was very user friendly..
    I will be moving next year and will be taking the Mini-Split with me to the new residence..

    My ? is ,I know how to pump down a unit ,with the proper gauges and vacuum pump.,but how would this apply to the DIY18K ??
    basically I am asking ,”when I am installing the unit back in the new location,do I follow the same procedures as when it was brand new,or do I need to purge the Lines like a normal non-diy install?
    I have searched for answers on Google but not alot of information as far as DIY pre-charged lines and what to do after disconnecting for move to new location

    1. When you’re taking it apart, you’ll basically want to do the installation backwards, so to speak. Make sure the valves are closed before you disconnect the refrigerant lines, of course. When you’re putting it back together, do it the same way you did it the first time. If ever thing goes as planned, you should not need to vacuum the lines or add any additional refrigerant.

      1. I don’t understand your reply. So, if the refrigerant lines are pre-charged, and then the DIY owner re-seals the outside unit ports (by closing the 5mm allen screws) to the lines, and then disconnects the lines. (I think these are steps you’ve outlined, above). Then, when the lines are disconnected from the outside unit, the lines lose their charge.

        At that point, at re-installation time, the DIY owner is calling a tech to vacuum purge and re-charge the lines.
        Right?

        I’m attempting to be clear, and demonstrate you’ve apparently left something out of your explanation of re-connection.

        1. They should not lose their charge. The connection couplings should mechanically close once they’re detached.

        2. Bob, I believe the lines have internal stopper valves at the coupling ends. The stoppers are pushed open when the coupling is screwed together, but when unscrewed, either internal pressure or a mechanical spring closes the valves inside the lines.

  11. I found your air conditioners and the reviews are great. They are back ordered or not available every site I find. What is your production schedule? I’m looking to get one delivered to Home Depot in Galveston, if that matters. Looking forward to installing a 36K DIY in my beach house. My window units can’t keep up!

    Thanks!

    Lane

  12. On the 18k diy mr cool one line set is bigger around than the other does it matter which one screws onto the top and bottom of outside unit?

    1. Make sure you connect the line sets properly in accordance with the instructions in the Installation Manual. Yes, one is larger and one is smaller, and it does matter where they are attached.

  13. The manual shows the location of the pass thru hole in the wall is either in the lower left or lower right corner of the indoor unit. The unit as delivered has the tubes bent tightly to cross over to the right side, then the tubes are wound up in the box in what I can only describe as a tight oval. I was going to install the pass thru on the lower right (facing the unit), but the bend in the tube there is pretty tight and I am fearful of bending the tube too tightly or even kinking it, or breaking it if I try to straighten it out. Is there any reason I shouldn’t make the pass thru hole more toward the middle of the unit (just inboard of the wall bracket)? Then I would be bending the tube in a place it has not been prestressed.

    Otherwise, is there a procedure for unbending the tubes to get the pass thru on the right side without risking damage?

    1. I don’t know of a reason why you couldn’t modify the position of the wall hole so long as it can be maneuvered through undamaged. I would recommend you follow-up with our tech guys. Call 270-366-0457 and ask for tech.

  14. Re: DIY 18 for 750 sq ft shop, well-insulated, eastern MA. You’ve stated that lowest outside temp for heat is “low teens”. Is this for making its rated amount of heat, or for making any heat at all? Thoughts on installing compressor in adjoining garage, which even though unheated, never gets really cold (below 15-20°)? Would that benefit the low-temp winter operation? Or should I leave my oil burner functional?

    1. There are a lot of factors to take into account in your example here. Any heat pump, ours or otherwise, takes heat out of the air and puts it inside your house. The colder it gets outside, the harder it is for the unit to gather that heat, so efficiency drops. The AHRI only rates units down to 17 degrees, so that’s the lowest verifiable operating rate we can provide. If you had the condenser in an insulated garage, that could help maintain even efficiency for a longer period of time. However, while the interior air handler would be heating your shop, the condenser in the garage would, in effect, be acting as an air conditioner. The garage location would benefit winter heat pump heating, but at some point, I’m not sure exactly when, the condenser would cool the garage to such an extent that it compromised its own efficiency. Personally, I would try to get as much heat as I could efficiently from the mini-split, then turn the oil burner when it just gets too cold.

      Hyper heat units like our Oasis Hyper Heat and others can handle lower winter temperatures, but, since they’re heat pumps, all of them ‘bottom out’ at some point.

      1. I appreciate your reply, and that makes sense. Gets into the question of how much “heat” can you suck out of “cold” air. As an aside, the shop equipment generates waste heat in the room, and I really don’t need supplemental heat until the outdoor temp is below 30-ish. Bigger issue is winter nights, when the outside temp can be lowest, machinery is off, and I want to maintain that equipment at 60-65. I’m only at the early investigating stage, and again thanks for the reply.

  15. I understand one should switch to other heat sources past -17 degrees, but I would like to know if the unit compromised at colder temperatures (Canadian winters can get below -40)? For example, if I accidentally don’t realize the tempature has a sudden drop to -20, will it simply be ineffective or can it potentially hurt the unit? Also, is it perfectly safe in extreme cold when shut off for the cold winter months?

    1. It will shut down and go into defrost mode. Being exposed to extreme weather should not damage the condenser. It is a good idea to prevent snow and ice from building up around the condenser, but that’s a good rule to follow with any HVAC unit.

      1. AHRI rates heat pump efficiency down to 17 degrees, so that is correct. But where did you get the -17 number from? I’m not aware of any heat pump that would heat efficiently that low.

        1. The user “me” on August 1, 2017 at 11:07 am said “I understand one should switch to other heat sources past -17 degrees” and I wanted to clarify for anyone else who came across the post that it’s 17, not -17.

    1. Everything should be in stock right now except for DIY 12k units. More of those should be back in inventory in 3-4 weeks.

  16. I would recommend MRCOOL to start making pre-charged lines in different sizes like 5′, 10′, 15′, 20′ 25′ and so on. One should be able to order it based on one’s requirement. In my case I want to buy 5 DYI unit but with different sizes of lines to make the installation looks better. What are your thoughts.

    1. This is something we go back and forth on. On the one hand, we want to give people as many options as possible. On the other, we want to minimize the potential for an install going wrong, and different length linesets would necessitate a non-factory installed connection to the air handler. It’s a tough call. We’re going to stick with a single lineset size for now, but that may change in the future.

  17. Can I mount the outdoor compressor unit on the roof about 5 ft. above the indoor unit? Unfortunately I can’t mount the outdoor unit on the ground below the indoor unit and meet the 12 inch clearance criteria behind the unit within the 26 ft. coolant line length. Do I have to worry about sun exposure of the unit on the roof. I live in AZ.

    Thank you

    1. The compressor can be mounted in any relation to the air handler so long as you make sure the drain hose is configured properly. It should still work in direct sunlight. If you can arrange some sort of shade, that would be ideal though.

  18. I just installed a 12 k DIY unit on our 4 season room and it works great but I really wish you could provide different length line sets to make the end job look much neater. I saw an earlier comment that said “I would recommend MRCOOL to start making pre-charged lines in different sizes like 5′, 10′, 15′, 20′ 25′ and so on.” Why would it necessitate a non-factory installed connection to the air handler? I know a production lines like one size fits all but many of us would gladly pay the extra cost to get the line length we need with the correct charge. I currently have a need for another unit with a line set of 6 to eight feet and would love a DYI solution again but with the length issue I’ll go with another product that wont be DYI. I’ve read that coiling extra line set be-hide the condenser is not a good thing and could create oil traps bla, bla, bla. You guys are close to making an even bigger hit than you already have with a few tweaks like different line set lengths.

    1. We would love to be able to do it, and we’ve had a lot of internal discussions to that end. As of right now, we won’t have variable lengths in 2017-18. There is a chance we will develop a variable lineset DIY product by 2019 though.

  19. Thanks for your reply. I understand that gearing up to make a change like variable line sets might take awhile but can you comment on coiling up extra line set and storing it behind the condenser? It it in anyway detrimental to to the compressor? Will it cause an oil trap? The “non-DYIers say it’s bad for compressor life. Besides looking like you know what, is coiling up 20 feet of it ok?

    Thanks again.

    1. Carefully coiling the excess lineset behind the condenser should be fine, but make sure it does not interfere with air flow through the condenser. It should not cause a problem.

  20. Hi. I’m looking to purchase and install a 12k DIY unit for my home office in the basement of my house. The floor above the basement overhangs front and back around 2′ each.

    In the instructions, the drain line is bundled with the rest of the line set. Would it instead be possible, for a neater installation and a smaller hole through my concrete block, to coil the line set in the overhang immediately above the outside unit (and drop the line set from there), and separately have a smaller hole through which the drain line would go?

    This way, the larger hole gets drilled through the wood overhang, line set is concealed (distance from the inside unit to the outside would be all of maybe 6 feet of line), and the drain hole is much smaller.

    I assume the only line where downward angle matters is the drain, right?

    How tight can the line set coil get before kinking? Could it fit between 16 OC joists in that overhang?

    Thanks!

    1. You are correct that the only line where downward angle matters is the drain. It can be separated from the other lines. You can really do anything you want with it so long as it will drain properly.

      In terms of how ‘tight’ the line set coil can get before kinking, there is a lot of flexibility in the lines. It should be able to fit between 16″ joists. Just be careful, of course.

  21. I bought the 24k Mr. cool for 240 volt. The wire diagram shows L1 red and L2 black and ground. Where does the neutral (white) go? On the ground screw with the copper wire?

    1. If you have a WHITE conductor in your power supply cable, it should be attached to the ground screw with the bare copper ground, both at the unit and the disconnect. A 220v circuit does not have a neutral.

  22. One of the posts above you said that an installed unit may be uninstalled and moved without recharging if done properly. Can you list the steps necessary to accomplish this as I need to move a 12k unit and replace it with a 24k?

    1. The key area to focus on is the refrigerant piping connection on the condenser. Refer to section 6, page 23 in the installation manual. Basically, you are going to run the piping connection install process backwards – remove the valve covers, close the valves with a 5mm Allen wrench turning clockwise, replace the valve covers, use wrenches to open the connectors, attach the plastic seals (if you still have them) to the connectors. Obviously, the unit should be completely turned off/disconnected from power when you do this.

  23. Having trouble getting these shipped to Hawaii, is it because they are pre charged? Ca these be transported by normal methods such as FEDEX or would they need to ship by boat?

    1. I’m not an expert on shipping to Hawaii. However, we ship them to customers using normal means, so there should not be any special requirements.

  24. I understand that your standard units are rated to produce heat down to 17 degrees, and that for colder climates, you offer the Hyper Heat series. Is there any DIY product that offers Hyper Heat?

          1. I’m sorry to hear that. For what it’s worth (Which I realize isn’t much) I’ve got two floors that I want to put systems in. Each requires dual zone, and I’d like to do hyper heat. The DIY option is what attracted me to MrCool, but if I can’t do that without voiding the warranty by using a non-DIY unit, then I’ll probably go with a local pro installer, and the systems they carry, even though it will likely triple what I end up spending. Thank you for your quick responses.

          2. The number of contractors installing MRCOOL products across the country is growing. Have you tried looking for a MRCOOL dealer in your local area? Alternatively, you may be able to find an installer willing to use equipment you’ve already purchased. Not all installers require their customers buy directly from them.

  25. We live nc mountains in zone 5 but our temps seem to be a little different then most zone 5. Our average high in July is is 71 but only above 80 for about 10 days during the entire summer. Our average low in Jan. is 19.

    Our home is about 12K sq. ft. and I can mount the air handler in the cathedral ceiling wall in the center room of the house. The main reason for wanting a unit is to remove humidity when it hits those 10 days or so during it gets over 80 degrees

    I am thinking a 18K would be better than a 24K to get the humidity out as it would run more. What do you think?

    Also since the unit would be in the middle of the house which unit (Oaisis or DIY)would give better distribution of air flow?

    And one more. Could you explain how the hyper heat is different from the regular Oasis unit and what the benefit would be for my application?

    Thanks

    1. An 18k that runs longer would dehumidify longer. However, you should get the size you need. If you need more dehumidification, we recommend you switch the unit to Dry Operation. This will provide more dehumidification.

      In terms of air flow, there shouldn’t be any significant difference between an Oasis and a DIY.

      The Oasis Hyper Heat performs more efficiently at lower temperatures than a DIY unit. For example a 24k DIY (AHRI 8994007) unit will produce about 15.9k BTUs at 17 degrees. An Oasis Hyper Heat (AHRI 8977714) will produce about 17.2k at the same temperature.

      Also, when you said you have 12k sq. ft. did you mean 1200 sq ft or 12,000? Because if it is 12,000, I think you might need more than one ductless unit to cover that!

      1. Thanks for your quick reply,

        I meant 1200 sq. feet and the room I want to put the air handler in is in the middle of the house. Wooded area not a lot of direct sunlight. Still think I need more than a 18K unit?

        What is dry operation?

        Would 15.9k BTUs at 17 degrees be able to maintain a temperature of 70 degrees in a 1200 sq. ft. house?

        1. Given your summer temperatures are rather mild, you may not need more than an 18k

          Dry operation is when the unit runs on a lower cool setting, so that it runs longer and dehumidifies more effectively. If the interior temperature is where you want it, but it’s still a bit too humid, let the unit run on dry mode for a while.

          As to your question, I’ve sent a message to the tech guys to find out what they think.

          1. So, here’s what one of our tech guys said, “I have no idea what the btu requirement for the specific structure is, however my best guess is probably not.”

  26. Hello I have purchased one of your 24k DIY units but would like to shorten the lines. I know that the Hyper Heat models specify a minimum line length of 10 ft before needing to remove refrigerant however there is not a length specified for this model. Could you give some insight on what this length would be?

    1. We do not recommend modifying the length of the line set at ALL on a DIY unit. If you want a unit in which the line length can be modified, we recommend our Advantage Series. Since the DIY lines are pre-charged, they would have to be vacuumed before modifications were made. Which would also necessitate vacuuming the air handling unit, since the line set and the air handler are preconnected. Without proper licensing, modifying the line length on a DIY unit would void the warranty.

      1. I have an HVAC technician that could vacuum the lines. Isn’t it the unit that is precharged opposed to the lines?
        What would you recommend doing with the excess line?

        1. On the 2nd Generation DIY unit, the line sets, the condenser, and the air handler are all precharged. Customers do different things with the excess line. Some people bundle and leave it propped behind the unit, some build boxes or other housing to store the unit, some have it running along the wall protected with LineGuard, etc. It just varies from customer to customer. Again, if you’re going to have to go to the trouble of having a tech vacuum the lines, I really do recommend the Advantage over the DIY. The DIY is designed to avoid that sort of thing, but the Advantage will work just fine. And it’s cheaper!

          1. Josh, the whole point of the MrCool DIY series is that you don’t need to mess with the lines. There’s no vacuuming needed, there’s no HVAC license needed. There’s no special tools needed. This is all thanks to the fact that they already have refrigerant in the lines, whereas most HVAC eqipment is sold with lines that require all that additional work and expertise.

            The disadvantage to the DIY line is you end up with pre-determined lineset lengths, and may need to coil it up somewhere.

            What the MR COOL rep is trying to tell you is that if you aren’t okay with having that excess lineset laying around, then their non-diy systems would have been a better option. The Non-DIY linesets don’t have refrigerant in them yet, so they’re much more practical for a licensed technician to modify. If you want to modify the lines on a DIY system, you not only negate all of the benefits of getting a DIY one, you also have made more work for the technician vs just getting a non-diy system to begin with.

          2. Would you be able to tell me if the bolt mounting pattern on the outdoor unit of the Advantage 24k unit is the same as the DIY 24k unit? If so I will return the DIY in exchange for the Advantage.

  27. Hi I have received my DIY 24k and notice it comes with a sealed bag of neoprene. What is this for? It doesn’t seem to say in the instructions.

  28. Forgive me if this question has been answered. My eyes started to blurr reading all these great posts and replies.
    I just purchased the DIY HP 18K 230A. I will be installing in my detached garage/shop/man cave (550 sq ft). I don’t care if the lines are mounted inside or outside. Is there any advantage/disadvantage to the location of the bulk of the 25′ lines?
    Seasonal exterior temps range from avg mid 90’s in summer – avg mid 30’s winter. The garage is finished and insulated.
    Thanks

    1. Whether the bulk is inside or outside, there is unlikely to be any performance difference that you would notice.

  29. Do these units have a condensate pump, or do they just drain by gravity? I’d like to install one on an interior wall and run the linesets through the attic. If there’s no pump, I guess pI’ll have figure out somewhere to drain the condensate inside the house.

  30. On your 24000 diy pump, installation was a breeze watched the video and pretty self explanatory. It was shipped in the most armour plated setup I have ever seen, job well done. But you need to include a weather tight fitting for the indoor unit to connect to the compressor. The clip is to big for any type of normal fitting to work. You have to cut and resplice to get it to work. If you fixed that and had a option for shorter linesets or custom lenghts you would sell me 2 more for sure.

    1. Different lineset lengths is a common request. We have been exploring that option for a few years. Hopefully we get it on the slate in 2019.

  31. Is there a programmable thermostat available for the 36k DIY? If not is there some way to set different temps for different times of day, e.g. 74 8a-8p and 78 8p-8a?

    1. There is not a programmable thermostat available. You can use the remote to program the unit to change temperature at a set time.

  32. I need a 35’ line set. Can I purchase a pre-charged line set from a mobile home site and use it with a MrCool DIY unit?

    1. Definitely an interesting idea, but it won’t work without a lot of headache. The lines on the DIY are pre-connected to the air handler, so you would have to do some fairly significant modifications to remove it and attach another line set. All of which would definitely void the warranty.

  33. I’ve purchased and installed two of your DIY units, a 24k and a 12 k unit. They both work great and I’m planning on buying another 12k unit soon. Excellent product!
    I have two questions/comments.
    1. When using the sleep mode it would seem to me that it would make more sense if after going thru the seven hour sleep mode that the unit would return to the primary set temp. rather than shutting down. This would make more sense to me as most people would want the unit to crank back up to the primary temp. when they are waking up rather than shutting down.
    2. When using the wifi smart phone app I can’t find a way of seeing what the actual room temp. is. All it seems to show is the set point temp. I’d like to know the actual room temp. so I can tell if things are actually working correctly. I know somewhere in either the unit or the remote there is a temp. sensor that can read the room temp.

    1. 1. You could always use the Timer On button to set the time you want the unit to come on.

      2. While there is a sensor in the unit that reads the room temperature, this is not part of the data that the app can translate.

  34. I tried to use 10 ga wire to run between my disconnect and the condensor (DIY 18k), since that was what was on the old unit. I found that the L1 and L2 screws won’t clamp down on the thicker 10 ga wire. I went down to 12 ga, and they seem tight but those screws are awfully short. Any thoughts on this? Otherwise, I had no issues with the install. Thanks.

    1. If you are using solid copper 10 AWG wire, you can hammer it flatter to get it under the screws, or else attach spade connectors that can then go under the screws.

  35. I want to put your system on my third floor but I’m not sure the 25 foot line is long enough. Do you have longer pre charged lines that you sell?

    1. We do not have longer pre-charged line sets. However, you could use a wall mount to secure the condenser to an outer wall. Placing the condenser on the ground is not required.

  36. I have a 3 car garage where I planned to install a 24k DIY unit based on the information in previous comments. The garage is about 850 sqft. I used one of those online calculators, and the result indicated I needed only about 10k BTUs for cooling. So I am wondering if the 24k unit is overkill. Should I go with the 24k unit, or should I consider something smaller?

    Some additional info. I live in southcentral New Mexico (desert, very arid, except for monsoon season). The garage has no windows and no external doors (although I plan to put in a service door in the future). The garage doors are both insulated, and the ceiling height is about 9 feet.I plan to put in two ceiling fans as part of this installation to circulate the air.

    Thanks for the advice.

  37. I have purchased the DIY 18,000 BTU unit. I am going to cut the line set off and install a shorter line set. The liquid line consists of two small capillary lines that turn into 1/4 inch copper. Are these lines acting as the restriction in the system or is there a expansion valve closer by the evaporator. I am going to run one 1/4 inch copper and one 1/2 inch copper.

  38. I just got a 12k DIY unit and it has a big yellow sticker on it that says caution lines must be evacuated, I thought you dont have to evacuate these systems thats why i purchased it could you please shine some light on this subject as soon as possible Thanks

    1. The tag should definitely not have language about evacuation on the DIY. There should be a yellow tag that instructs the valves must be opened after a sealed connection is made. You should check the model numbers. Either you received the wrong product from the seller or the factory placed the wrong stickers (most likely the former).

  39. Why are you reluctant to offer a 2 or 3 zone DIY system?
    I think from a marketing standpoint it would be easier to promote than a 1 zone window unit alternative at your price point.

    1. From a marketing standpoint, a multi-zone DIY system is great. From an engineering standpoint, there are multiple issues that have to be worked out before the technology is ready for market. Multi-zones are just a lot more complicated than a single condenser-air handler set.

  40. I have just finished installing a DYI 24000 btu’s . My comments on it are .I saw some body posting about the screws that attach the wires in the condenser are extremely small , even after they are tightened the seem kind of flimsy at best .And I agree completely .
    Bought the unit to cool down a two story cabin and after a lot of debate about the air handler position , decided to install it in the second floor where it gets the hottest . That left the kitchen – living room area a little warm . As an experiment dug a hole in the living room ceiling leading to the upstairs room floor and installed a little fart fan that was laying around as an improvised air circulator … Man the difference was amazing…the hole house got so cold we had to raise the temp because it got so cold .Super happy with the unit and I would recommend your product to anybody . The noise level of this thing both inside and out is ridiculously low , the build quality looks great .

    Which leaves only one question : Can the lines be mounted flush to the side of the unit ? I have seen some cut-off’s on the side of the air handler …but can the lines be bent all the way to the right of the air handler as to mount the lines flush to the inside wall ? Which would basically mean : Can the lines on the air handler be rotated 180 degrees from the original packing position ?

    1. Glad you’re enjoying the unit, Andres! As to your question, the lines can go out the right side of the unit, flush with the wall (which is what I think you are asking). The only caveat would be to ensure the drain hose is angled properly.

  41. Most any HVAC how-to says coiling refrigerant lines is a no-no. Something about trapping refrigerant oil.
    So with the outside unit sitting below an inside unit on a single level home, I’ll have about 15 extra feet of line set – and I can simply coil it? Horizontal or vertical? Does it matter?
    Has something changed over the years in line sets?
    Thanks!

    1. If you are going to coil it, coil it horizontally behind the unit. Many homeowners run the full length of the line set down a wall to keep it as straight as possible. For example, you would run it down to the ground, then left or right across the the outside of the building, then install your condenser at the maximum extension point. I just think it looks a lot neater that way, and you don’t have to have the extra coiled line laying around anywhere. As to line sets and refrigerant oil, I know that can be an issue with slight kinks or leaking, but properly installed that shouldn’t be an issue.

  42. Well the DYI is out. I planned on installing on n outside wall, but I have a nice looking house and coiling 20 feet or so of line behind the unit is not appealing. I had nearly decided to go with the Advantage and pay someone, but the warranty is terrible. Why is the DYI warranty three time longer? Seems counter intuitive. Also, does the contractor need to do the full install to avoid voiding the warranty?

    1. A contractor would need to install the Advantage to ensure the warranty is valid. The Advantage is an economy product, so the warranty terms as not as beneficial as a premium model like the DIY. In terms of installation, you don’t necessarily have to coil the lines behind the unit. If the environment around the site permits, you can move the location point of the condenser, run the line along the length of the wall, and conceal it with an attractive cover set like our LineGuard.

      1. Mr. Cool continues not to recognize the need to custom make the desired line set length. Doesn’t seem like it would cost them anything to lope off 10 or 15 ft. of line set. Even if they charged more for the service I don’t think we would mind to make it look better. They say if your going to coil the line set, coil it horizontally behind the unit. Can you imagine how awful that would look mounted on an outside wall?
        I installed a DYI unit and played out the 25ft of line set when I only needed 15. Installation could have looked much better. I would have installed another DYI unit at another location but I only needed a 6ft line set so I went to a different brand and paid a small fee for having it done right. I’ve seen many posts asking for different length line sets so they must not need the business that bad to give the customer what they want.

        1. John, we definitely recognize customers want a variable line length, but, unfortunately, it is not as easy as we would like. It is something we are working on, and it is an option we will offer as soon as practicable.

  43. As a follow up, most people install on the outside wall (I assume). Seems like you would save considerable money on lines and refrigerant with the shorter houses, and frankly sell more units.

    1. Yes, most people do install the condenser on an outside wall. We currently offer 25 foot refrigerant lines to ensure the product is as flexible as possible.

  44. We are getting ready to install a 9000BTU unit 240 volt. The spec calls for using 14 gauge wire with a 15 amp breaker. This seems undersized to me. I would go with a 12 gauge wire and 20 amp breaker. What do you think?

  45. What’s the difference between a advantage 18k unit and a diy 18k unit? Why do I need to evacuate one and not the other? Both look to have the same linesets and connections? I am in New England and am looking to get some heat in the shoulder months are there any advantages to one or the other or the hyper heat?

    1. The Advantage is a conventional ductless mini-split. The DIY is designed for do-it-yourself connection, so the lines are pre-charged and sealed. No vacuuming or charging the system is required. Which means they are much, much easier for the average person to install. The Oasis Hyper Heat is designed for cold climate heating. If you’re in New England, that might be the best option for you.

      1. And can you get a hyper heat with pre charged line sets? I am a home builder so the installation should not be a problem i have evacuated units before helping my HVAC guy but I have heard that if it’s not installed by a licensed tech voids any warranty?

        1. Unfortunately, the Hyper Heat is not available with the pre-charged line sets that the MRCOOL DIY comes with. The warranty for the Hyper Heat does require “a state certified or licensed HVAC contractor”. So long as your state certifies you to install equipment like this, your warranty will be honored.

  46. I’m thinking of installing a couple feet above the ground, can i coil the extra line horizontally, underneath the unit? For the 220 volt unit, would i run just three wire, L1, L2 and ground, no white neutral? Color suggestions for the wires?

    1. Yes, you can coil the line horizontally. For electrical questions, please contact our tech support at 270-366-0457.

      1. Is the DIY 18k unit AHRI Certified? If it is, I can get a rebate from my power company.
        Rebate verbage
        ◦Your new ductless system must be AHRI Certified® as a mini-split heat pump, use inverter technology, have a minimum HSPF of 9.0, and be a minimum of 1.0 ton in heating mode.

          1. Great!

            Now i see they want the certification number. Can you provide that for the 18K unit?

            TNA

  47. I have just ordered the DIY-24-HP-230A. I am anxious to install it. Were in the middle of a heat wave here in East Texas. I want to make a concrete pad with four bolts sticking up to hold down the outdoor unit. Could you give me the exact measurements of the holes in the feet of the outdoor condenser? Also, all of the install videos show people running the lines out of the right side of the indoor unit. I am wanting to go out the left side. Does the left side work and look just as good?

    1. The distance between the holes is 21.5″ long and 13.25″ wide. The conduit cable can go out on either side of the air handler. There are perforated sections that you can knock out to accommodate the install. As far as how it looks, well that is in the eye of the beholder.

  48. Can I run the 25′ DIY pre-charged lines upwards into the ceiling from evaporator on bedroom wall, and than snake it horizontally across the inner ceiling to adjust the length, than down the wall to the condenser on outside house?

    1. You can run the refrigerant line and the communicating wire in that way. However, the condensate drain must always be angled downward to prevent water leaks.

  49. Two more questions. Is the Advantage a variable speed compressor?
    If I run 50′ lines to the Advantage and I vacuum it, will I have to add freon since lines are over 25′ ?

      1. I thought the Advantage was a 2 stage because there was no mention that it was a variable speed?
        If I use 25′ lines on the Advantage can I just vac and avoid adding freon?

        1. It uses a variable-speed inverter. You shouldn’t have to add any charge for the Advantage with 25′ lines, but you should always check with gauges to ensure it is properly charged before activation.

  50. Last question. Can I oversize a variable speed split a/c buy putting an 18k DIY in a 300 square foot master bedroom with 10′ ceilings, walk in closet, master bathroom. BTU Calculators come up with 12k. I have read that oversizing an inverter variable speed is ok and may be better. Thanks.

  51. Hi , I have a small house 976 sq ft, one large open living room kitchen combo and down a narrow hallway 3 small bedrooms and one small bathroom. I was wondering if I should purchase the DIY 36K BTU unit and place it in the living room across from the hallway if it would be capable of cooling and heating the whole house, if I were to install ceiling fans in all the bedrooms and living room. I currently have gas wall heaters and am getting new vinyl windows installed. I live in Southern California and have a 1950s build no insulation house.

    1. Properly placed, a ductless product like the DIY 36k can distribute conditioned air very effectively. Ceiling fans will help as well. An alternative would be a multi-zone with two or there smaller capacity air handlers. However, the DIY 36k is definitely the more cost effective choice.

    2. I don’t know where you live but it sounds to me like 36K would be over sized. I am considering both the DIY and Oasis Hyperheat units. I can do the DIY unit myself but the Oasis unit has better features mostly savings on heat but also the air distribution is better. I will do almost all the Oasis unit myself but will need to get a licensed HVAC person to do the final hook up of the lines and charge the system so it will cost me a little more than the DIY unit.

  52. Hey:

    I live in a cold area where -4F is not unusual for a few weeks of the year. I have been trying to figure out how many BTUs are produced by the hyper heat as the outside temperature declines from 20F to -20F. Is there a chart for that?

    It is hard to figure out what size to buy without this data because I have to buy for the cold days.

    Thanks.

    1. The exact BTU performance would depend on the particular Hyper Heat model. For example, the 24k produces 24k BTUs at 47F and 15400 at 17F. Performance will depreciate accordingly down below zero, and the unit must spend some time in defrost mode to prevent ice from building up on the coil.

  53. Just installed a Mr Cool 12000 DIY , was real simple compared to the other 4 LG ones I did prior although this installation was a little more complex on where the wall unit was ( 2nd floor ) versus the outside condenser but hey I am cable guy for 34 years so running wire and hiding it is my deal .My only concern is , as read prior posts , if you need just a little more feet on the precharged line sets. Just wondering why there’s not an additional kit you can buy with the connectors and let’s say a 15′ precharge line set that can be purchased separately to get you where you need to go ? Tell Mr Cool they have a great product blows away the rest !! Lastly , my friend , who is a HVAC , was so impressed with my other mini split installs offered me a job ! lol

    1. It is as fool proof as we can make it. The connections are different sizes, and they have different colors. Connect the ones with gray caps together, and then connect the ones with blue caps together.

  54. Purchased and installed 18k diy mini split over 2 years ago and couldn’t be happier. I’m writing to ask for instruction for cleaning the indoor unit. All mini splits are prone to mold buildup on the blower wheel. Can you provide instruction for removing the cover and cleaning the coils and blower wheel? A video showing this cleaning would be great!

    1. The indoor air handler definitely does need to be cleaned. We would recommend you use a mini-split bib kit. We do not sell them ourselves, but you can find them online for reasonable prices. When you’re cleaning the product and need technical support, you can always call us at 270-366-0457.

  55. Building a 48′ x 24′ garage with lots of windows. The back half of the garage has a ceiling height of 20′ and the front half is 9′ tall with a loft above it. Thinking about installing 2 mini split units to cool and heat my garage. I live in Utah where temperatures are commonly below freezing in the winter and 90 to 100 degrees in the summer. What size units would you recommend?

    1. This is not an exact science without seeing the space, but I would likely recommend two units with one positioned in the loft and the other on the ground floor. Two DIY 12k or 18k units should be sufficient.

  56. I was just looking at Mr Cool 24k BTU Installation documentation and see reference to “2nd Generation”… Plan to buy on Amazon; how do I know if I’m getting 2nd Gen or not??? Thank you, Bob

    1. I’m a fan of Amazing for buying many things. But this would not be one of them. Who do you call with questions or problems? I have 4 of the DYI units that I installed in my house. I bought them all from Ingram’s Water and Air. Shipping was prompt and any questions I had were answered by them immediately

      1. Ingrams has these on their site already. They’ve been very helpful and responsive in my experience. That would be my choice.
        I have two of them and they’ve been nothing short of fantastic. 😉

      2. That’s a good question Dale and I honestly don’t know for sure but what I can say is that while I’m buying the Mr Cool mini split off Amazon, the “seller” is Ingram’s Water and Air… And Ingram’s seems to have a hight seller rating… I would think in this case and for this product and DEPENDING on what the issue is with the mini-split your recourse would be through one or combination of Amazon, Ingram’s, or Mr. Cool themselves…

  57. Can the DIY unit’s line set be bent 90 degrees in order to stay within a 2×4 wall? Ours is new construction so the studs are still open. If yes, from the back of the inside unit, can the line set run up into attic, make a coil of extra line set up there, then travel down between studs and exit with a 90 bend to the connect to the condenser? My goal would be to avoid having a coil of line outside.

    If all this is practical, can the drain line be easily separated from the line set so that it can run directly downward for its pathway outside?

    Thanks

    1. Yes, you can do that, but you can’t do a ‘hard’ 90 degree turn. It will need to be more of a swooping bend. Be careful not to kink or crimp the line while bending it. Otherwise, everything else in your plan is good to go.

    2. Condensate drain can exit right or left on the air handler and can be completely separate from the line set.

      The first couple of feet on the lineset is very rigid and either exits straight out the back on the left size, or it fits in behind the air handler and exits on the right side. Since this part of it is so rigid, surely bending it 90* into a 2×4 stud wall would kink it. You would want to remove the insulation and use a tube bender, or at least ensure that it does not kink.
      Personally I would not hide the lines – if you ever want to remove the DIY unit it comes off WITH the line set. JMHO.

      I don’t see a problem running up then down, but perhaps an installation pro can chime in on that. Many have been installed with excess lineset coiled behind the compressor or otherwise vertical coils, however the majority of installers frown on this and even MrCool advised me that the lineset should be arranged in a horizonatal sloping fashion so that compressor oil cannot collect in the line loops.

  58. Thank you both for the comments. It sounds like its questionable to make the 90 degree swooping bend at behind the air handler and also again down near the outdoor unit, [which would keep the line set inside the wall for a neater look].

    The comment about the line set being part of one (?) of the units and hinting that future changeouts could be a problem, makes me wonder if I shouldn’t purchase the ‘non-DIY” system for my situation [ whereas I don’t want to see the lineset in any manner running down the outside wall]?

    Best Regards

    1. That’s one option. I would discuss it with a professional installer – one that can do the work and one that will guarantee it to work successfully.
      The only difference between the DIY and the non-DIY is the connector for the lineset – everything else is the same. So you can do it with your DIY unit, just know that if you will like never be able to remove said lineset. Otherwise it should no pose a problem should the air handler need replacing, you can disconnect it there. Also know that you would then need a conventional vac/test/charge and turn up like a non DIY unit.

      In my case, if either component fails, we simply shut the valves off and disconnect the lineset and power, and replace either component, hook back up and go. And I’m not hiring a $150/hour HVAC guy to try to get it to work. And when it doesn’t he’ll tell you it’s not his fault. 🙂

      1. The DIY lineset can be safely disconnected without specialized tools should you ever wish to move the DIY unit to a different location.

        1. Hmmm…I thought that’s what I said. Perhaps it wasn’t clear.
          The lineset connectors have a shraeder type valve that isolates and caps them off.

  59. Ah, re-read what I originally posted – about disconnecting from the air handler – so that has the same shraeder valves on that end as at the compressor end? Can be disconnected from either unit then?
    If that is the case I was not aware of that.
    And if so then what is the design purpose of the straight section of rigid pipe at the air handler end? It makes installing it much more difficult than at the compressor end.

    1. The first generation DIY units did have valves at the air handler that could be disconnected. The second generation is connected directly to the air handler. They could not be disconnected from the air handler without specialized tools and equipment.

      1. So I was right in the first place. Thank you. LOL
        Why is the lineset rigid for the first couple of feet where it is connected to the airhandler?

        The rest of the lineset is super easy to deal with, very flexible and easy to run. Getting the last feet of it and the handler fed through a wall port and the unit hung is much more difficult, especially with a 2 or 3 ton unit up a 10′ ladder.

  60. When will 3rd Gen DIY become available? My install requires a run over 25 feet and I heard the 3rd Gen DIY may have an option for different length pre-charged lines.

        1. We are interested in offering pre-charged lines in different lengths, but we cannot commit to a release date for those products at this time.

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