Mini Split Line Set Minimum & Maximum Length (An Easy Guide)

The illustration above from a Daikin Installation manual shows a caution about line set length. Every manufacturer will explain this differently.

How do you find the minimum and maximum line set length? The forums are filled with incomplete answers to this question. In order to know the correct answer you have to look at the installation instructions for each manufacturer of ductless units. There is no one size fits all for mini split line sets.

And remember this is a guide. I’m doing my best to aggregate and pass along good information. Your best support is in the next paragraph. Because some installation instructions omit the minimum length of line sets.

The best way to find the minimum and maximum length of your line set is to call the tech support line for the manufacturer of your mini split. They can be very helpful if you’re patient enough. They want to help because they don’t want problems. It’s a bad reflection on their name.

• Fujitsu tech support (866) 952-8324
• Mitsubishi tech support (800) 433-4822
• Daikin tech support (855) 770-5678
• Gree tech support (888)850-7928
• LG tech support (866) 526-0152
• Mr Cool tech support (270) 366-0457

Most HVAC problems, whether it’s a gas furnace, a heat pump or a plain old ordinary air conditioner, are installation related. A fact that most home owners simply cannot understand because they relate problems to brand name and it’s just hardly ever true.

So get the line set length right. I’ve compiled an easy reference to three major brands of ductless mini splits, Fujitsu, Mitsubishi and Daikin. Not all the information you need is here but you will learn how to find what you need.

Fujitsu Line Set Sizes And Lengths

Important note: All line set lengths are combined lengths. Meaning you need to add the full length of both lines. The smaller one and the larger one. Another reason to call tech support and ask that question. If you’re like a lot of folks, those little one liners in the installation manuals are easy to miss.

Mitsubishi Mini Split Minimum And Maximum Line Set Length

I called Mitsubishi tech support and they told me that they did not have a minimum length BUT, when under 10 feet they said there are a few noise problems like vibrations and so forth. So the best practice would be to move one of the units to obtain a 10′ minimum. The other option is to live with a little noise.

I was just at a customers house the other day and he complained about a vibration. She couldn’t hear it, but he could. Turns out he’s hyper sensitive to sounds and vibrations. The outdoor unit was mounted on an outside wall to the kitchen.

The unit was running normal with very minimal noise or vibration, but the little metal match holder just inside the house from the unit would rattle ever so slightly when the unit was on. Fix it with duct tape, right?

The Maximum And Minimum Line Set Specs For Daikin

Daikin is one unit that I’m just going to refer you to the long line set application for R-410A pdf. This is one of those engineering pages that adds a lot of information that requires you to add so many feet to every bend in the line set.

So if your installation is one where the length is fairly short you have no worries about 90° and 45° elbows. Just keep your bends at long radius’s and not too many of them. If you are having to make an extremely long run then call customer support if it’s too complicated for you to figure out on your own.