What are Pre-Charged Line Sets?

You often send us questions about pre-charged line sets, what they are, how they work, and which ductless mini-splits can (or can't) use them. Here are the answers you need to know.

What are Pre-Charged Line Sets?

During a normal HVAC installation, a professional needs specialized equipment and training to connect refrigerant lines. They must properly measure, vacuum, and charge the system. This is essential to effective and efficient performance.

Pre-charged line sets don't need any of that. They plug in relatively quickly and easily, because they come straight from the factory sealed and pre-charged (hence the name) with the appropriate refrigerant.

How Do Pre-Charged Line Sets Work?

Connect the custom lines to the custom condenser, tighten everything up, open the valves, and you're up and running. The specialized fittings on the condenser and line prevent any refrigerant from escaping during installation.

Which Mini-Splits Use Pre-Charged Line Sets?

To the best of our knowledge, MRCOOL DIY ductless mini-splits are the only ductless split systems that currently use pre-charged line sets. There could be some knock-offs out there. For right now though, no other company supplies pre-charged line sets on anything close to the same scale. Basically, if you want a ductless unit with pre-charged line sets, buy a MRCOOL DIY.

Now, we must specify that not all MRCOOL ductless mini-splits offer this capability. The MRCOOL Advantage, and Olympus products all use conventional line sets. An installer must connect, vacuum, and charge these models just like any other normal mini-split. So don't buy a MRCOOL Advantage to save a few bucks and expect it to be as easy to install as the MRCOOL DIY. Same brand, different products.

Questions or Comments?

Do you still have questions about pre-charged line sets? Or do you just want to tell us what you think? Let us know here, on Facebook, or on Twitter.

18 comments (view/add)
  • Joe Osgood
    Joe Osgood
    Posted on 8/9/2019

    Can these lines be disconnected without losing the charge? Example. To move the condenser for service.

  • Kyle
    Kyle from Ingrams
    Posted on 8/12/2019

    With the MRCOOL DIY, if you disconnect the unit correctly, it will not lose the charge. That is not something they recommend though.

  • Ken ICE-Ashbrook
    Ken ICE-Ashbrook
    Posted on 8/16/2019

    Are the compressors pre-charged too? Seems like there would be a small vacancy in it to be evacuated?
    Thanks for great product.

  • Kyle
    Kyle from Ingrams
    Posted on 8/19/2019

    Yes, the MRCOOL DIY condenser is pre-charged as well. There is no need for any evacuation with the DIY.

  • Sebastian
    Sebastian
    Posted on 8/18/2019

    I need a system for 3 small room to install myself. Can you do a diy condenser connected to 3 rooms?

  • Kyle
    Kyle from Ingrams
    Posted on 8/19/2019

    Unfortunately, that is not possible at this time.

  • michael meglen
    michael meglen
    Posted on 8/19/2019

    Are there any diy for a 2 room system

  • Kyle
    Kyle from Ingrams
    Posted on 8/20/2019

    The MRCOOL DIY is currently only available in a single-zone installation.

  • Mike
    Mike
    Posted on 8/23/2019

    What if I need like 35 feet to go from a room over garage to condenser can I get a longer line?

  • Kyle
    Kyle from Ingrams
    Posted on 8/23/2019

    At the present time, the only pre-charged linesets we know of are 25'.

  • Larry Ethell
    Larry Ethell
    Posted on 2/10/2020

    My MrCool was supposed to have precharged lines. It stars right on the unit lines must be evacuated. I know the system is charged but I thought the lines already had a vacuum on them. I just purchased it from you 2 wks ago.

  • Kyle
    Kyle from Ingrams
    Posted on 2/10/2020

    Not all MrCool products have pre-charged lines. The MrCool DIY does have pre-charged lines. Their other mini-splits do not.

  • Alex
    Alex
    Posted on 4/12/2020

    Is an ISO licence required in Ontario to buy or sell a Mr Cool with precharged lineset?

  • Kyle
    Kyle from Ingrams
    Posted on 4/13/2020

    We do not require any special licensing for online purchase of our products.

  • Adam
    Adam
    Posted on 5/4/2020

    Can you connect two precharged line sets together?
    My current installed mini split is a 9k BTU Sanyo with flare nuts on the line set the length is right at 35'...If I buy a 12K BTU 115V Mr. Cool DIY with an additional line set will the line sets connect together?IE are the connections male female on the line sets?

  • Kyle
    Kyle from Ingrams
    Posted on 5/5/2020

    MrCool is coming out with coupler kits that will allow two pre-charged lines to be connected together. However, the MrCool DIY pre-charged line is only compatible with MrCool DIY units. It would not work on a Sanyo mini-split.

  • Jerry
    Jerry
    Posted on 5/30/2020

    I am installing an 18k DIY Mr. Cool and the linear distance from the indoor unit to the compressor is approximately 12 feet. The line set has a fixed length of 25 feet. What Is the best method to coil the extra 13 feet of length? Can I leave in a vertical coil? But if I do won't the refrigerant oil get trapped in each coil? Should I mount to the exterior wall bending the line horizontally for 4 feet (with a slight down grade) bend down vertical for a foot and then bend again horizontally back to the compressor? And lastly should the entire line set be higher than where it ties into the fitting on the compressor? Thanks for getting back to me.

  • Kyle
    Kyle from Ingrams
    Posted on 6/1/2020

    The manufacturer recommends coiling the excess and storing it nearby the condenser. Like you, we think that keeping it horizontal is the best option. If you can store it above the compressor, then do so.


* All fields required.

Your email address will not be published. Comments will display after being approved by our moderators. Comments may be edited for clarity.