Mini split line sets can be less than 10 feet to more than 160 feet.
Each manufacturer sets minimum and maximum line set lengths for their mini split heat pump systems. During pro installation, the line sets are customized to the exact length needed before the system is charged with refrigerant.
But the question you might be asking is this: How long are line sets available today? What are the line set lengths sold?
Prefabricated mini split linesets range from 15 to 100 feet. These line sets have flared ends with lineset couplings in place, ready to install. Both standard and precharged linesets are sold.
Terminology tip: While writing line sets as two words is fine and everyone understands what is meant, it is technically one word – lineset. Both ways of writing it are used here.
Precharged Lineset vs Standard Lineset
As you shop for mini split line sets online, you’ll find two types, precharged linesets and standard linesets, which are also called non-charged linesets.
You might have an option based on the mini split you purchase. Let’s look briefly at both.
If you buy a fully DIY MrCool or Klimaire mini split, then you must have a precharged lineset for each indoor unit.
You have choices for length. For example, one online seller offers precharged, R410A refrigerant linesets in 5 lengths from 15 to 50 feet.
Precharged linesets can also be used in most systems requiring pro installation! Many mini split contractors buy precharged linesets to save time on installation. It’s important to ensure, though, that the lines are charged with the right refrigerant.
These are used in two types of systems, semi DIY and professionally installed systems.
Semi DIY or partial DIY mini split heat pump systems get that name because they require one difficult step, which some people prefer to hire an HVAC technician to complete – vacuuming the lineset or linesets.
The outdoor units come with enough refrigerant to flow into the lineset or linesets and the indoor unit coil. The lineset must be connected and vacuumed to remove moisture and air. Then, the refrigerant valves are opened, and the refrigerant is released into the rest of the system. A manifold gauge is used to ensure the system is not leaking.
Professionally installed systems are just about the same with one exception – they typically do not contain enough refrigerant for the system to run properly. Therefore, they require additional refrigerant charge to be done by a licensed technician who is certified to handle refrigerant. It is our opinion that manufacturers do this to make sure that a pro is hired to “do the job right,” in their view.
Otherwise, installation is the same. The lines are vacuumed, refrigerant is released, and a gauge is used to ensure a leak-free result.
See this page for more details on full-DIY, partial-DIY and pro-installed types plus brands that offer each type.
Max Distance And Height Difference From Indoor To Outdoor Units
To ensure proper performance, a lineset can’t be too long or rise too high.
Here is the reason for maximum distances and heights:
In many applications, the heat pump condensing unit is set on the ground outdoors. The lineset is run up the outside wall, into the attic and then down into the zone where the indoor unit is mounted. Some indoor units in multi zone systems can be quite distant from the outdoor unit.
This table shows two specifications from major manufacturers:
1). The maximum lineset length.
2). Maximum height difference between the outdoor unit and indoor unit.
You might note that there is no exact correlation between max distance and max height difference. There is no formula, in other words. It varies by manufacturer.
Max Distance and Height Difference of Line Set By Brands:
|Brands||Maximum Length||Maximum Height Difference|
|mitsubishi||65 ft (9000 – 15000 Btu) 100 ft (18000 – 36000 Btu)||40 ft (9000 – 15000 Btu) 50 ft (18000 – 36000 Btu)|
|mr cool||82 ft (9000 – 36000 Btu)||49 ft (9000 – 36000 Btu)|
|fujitsu||66 ft (9000 – 15000 Btu) 165 ft (18000 – 36000 Btu)||49 ft (9000 – 15000 Btu) 98 ft (18000 – 36000 Btu)|
|gree||49 ft (9000 – 15000 Btu) 82 ft (18000 – 36000 Btu)||33 ft (9000 – 36000 Btu)|
|bosch||82 ft (9000 – 15000 Btu) 164 ft (18000 – 36000 Btu)||33 ft (9000 – 15000 Btu) 82 ft (18000 – 36000 Btu)|
|lg||65.6 ft (9000 – 15000 Btu) 164 ft (18000 – 36000 Btu)||39.4 ft (9000 – 15000 Btu) 98.4 ft (18000 – 36000 Btu)|
Common Lengths of Mini Split Linesets You Can Buy Online
Pros buy rolls of lineset and cut them to custom lengths, adding the fittings on the jobsite.
However, full-DIY and semi-DIY installers – usually homeowners and property owners – want to work with prefabricated linesets.
Here are the common lineset lengths sold online:
- 15 ft
- 16 ft
- 25 ft
- 35 ft
- 50 ft
- 100 ft
What are the Maximum and Minimum Length of a Single Line Set?
15 feet is the minimum, and 100 feet is the maximum. Those are complete line sets with flare nut fittings, ready to be installed.
Rolls of lineset for professional use are available in lengths up to 164 feet. It is likely they are made for the LG, Bosch and maybe even the Fujitsu maximum lengths, as shown in the Table.
What If the Mini Split Line Set Is Too Long?
We’re talking about ready-to-install linesets, not rolls of lineset that must be fitted with connections on the job site.
In other words, these linesets are for DIY installation and can’t be cut down to size. They are fitted with a mini split line set coupling on each end. It isn’t like wiring that you could cut and splice, so attempting to cut and customize the length is not a good choice.
If your mini split lineset is too long, the best choice is to coil the extra line. This is the most common solution.
What can you do with the coil?
You have a few good choices.
1 – Attic: If you are running mini split line set through attic space, it’s easy enough to lay the coil, aka loop of lineset, in a safe place where it won’t get damaged. This is the preferred solution for ceiling-mounted indoor units.
Tip: When it will be covered in insulation, you might want to flag the location of the entire lineset to avoid walking on it and to locate it if needed.
2 – Outdoors: We don’t recommend hanging a loop of refrigerant lineset on the outside wall without covering it. It’s not aesthetically pleasing and could be damaged. If leaving it outside is your best option, then consider building a small box to contain the loop, and fixing the box to the exterior of your home.
3 – New Construction: If this is a new construction project and drywall hasn’t been hung yet, you can place the coil inside the wall cavity.
Tip: We recommend doing this directly behind the mounting bracket for the indoor unit. This makes it easier to access. And if you have to cut into drywall to retrieve it for some purpose, the bracket will cover the hole you’ve made.
Bending and Unbending Mini Split Line Set
There are two reasons to bend lineset – “unbending” the coils to make them straight, and bending the line as it changes direction during installation.
Uncoiling mini split lineset: Do it slowly and gently. This video is tedious – and that’s exactly how a line set should be uncoiled. Slowly and methodically.
Bending mini split lineset: Most installations require gently bending the line set to about 90-degrees where the line enters the house from outdoors. This can be done without kinking it and blocking the flow of refrigerant.
This video shows the manual way to do it – but be careful!
There are kits available specifically for kink-free bending mini split line set, but they cost $125 to $200.
Tube bending pliers like this one cost a lot less, but we don’t have a recommendation on whether they can be used on insulated refrigerant lineset.