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.
|MODEL||DIAMETER||MAX LENGTH||MIN LENGTH|
|9RL2||1/4″ x 3/8″||66ft – 20m||9ft – 20m|
|9RLFW||1/4″ x 3/8″||66ft – 20m||9ft – 20m|
|9RLS2||1/4″ x 3/8″||66ft – 20m||9ft – 20m|
|9RLS2H||*||66ft – 20m||9ft – 2.7m|
|12RL2||1/4″ x 3/8″||66ft – 20m||9ft – 2.7m|
|12RLFW||1/4″ x 3/8″||66ft – 20m||9ft – 2.7m|
|12RLS2||1/4″ x 3/8″||66ft – 20m||9ft – 2.7m|
|12RLS2H||*||66ft – 20m||9ft – 2.7m|
|15RLS2||1/4″ x 1/2″||66ft – 20m||9ft – 2.7m|
|15RLS2H||*||66ft – 20m||9ft – 2.7m|
|18CL||1/4″ x 1/2″||66ft – 20m||9ft – 2.7m|
|18RLXFW||**||165ft – 50m||16ft- 5m|
|24RLXFW||**||165ft – 50m||16ft- 5m|
|24CL1||1/4″ x 5/8″||66ft – 20m||9ft – 2.7m|
|30CLX1||3/8″ x 5/8″||165ft – 50m||16ft- 5m|
|30RLX||3/8″ x 5/8″||165ft – 50m||16ft- 5m|
|36CLX1||3/8″ x 5/8″||165ft – 50m||16ft- 5m|
|9RLFCD||1/4″ x 3/8″||66ft – 20m||9ft – 2.7m|
|12RLFCD||1/4″ x 3/8″||66ft – 20m||9ft – 2.7m|
|18RLFCD||1/4″ x 1/2″||66ft – 20m||9ft – 2.7m|
|9RLFCC||1/4″ x 3/8″||66ft – 20m||9ft – 2.7m|
|12RLFCC||1/4″ x 3/8″||66ft – 20m||9ft – 2.7m|
|18RLFCC||1/4″ x 1/2″||66ft – 20m||9ft – 2.7m|
|18RULX||1/4″ x 1/2″||165ft – 50m||16ft – 5m|
|24RULX||3/8″ x 5/8″||165ft – 50m||16ft – 5m|
|36RSLX||3/8″ x 5/8″||165ft – 50m||16ft – 5m|
|18RCLX||1/4″ x 1/2″||165ft – 50m||16ft – 5m|
|24RCLX||3/8″ x 5/8″||165ft – 50m||16ft – 5m|
|36RCLX||3/8″ x 5/8″||165ft – 50m||16ft – 5m|
|42RCLX||3/8″ x 5/8″||230ft – 70m||16ft – 5m|
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.
Since you’ve read this far, why not travel just a bit further and scope out a couple of my favorite heating and cooling products and tools.
Thank you for reading my article. I hope the information has led to your ability to make good decisions in either working on or discovering how to solve problems in your home HVAC equipment. These are affiliate links, so if you do decide to use any of them I do earn a commission. In all honesty they are products that I would use in my own home or the homes of my friends and family.
Fireplace remotes by Skytech Remote Control Products . My wife loves this and it probably took all of 30 minutes to install. Replace that wall switch or thermostat for your gas fireplace. Easy installation and instructions. In fact I wrote an article that covers the job pretty thoroughly I think.
Honeywell Thermostats. My favorite two Honeywell stats are the T6 Pro and the 8000 Pro series but their is a bunch to select from besides those two models. You can select WiFi that has the capability of operating your system from your smart phone no mater where you are. Honeywell tech support for homeowners is the best out there. Call them if you need at 800-468-1502 or comment below if you have questions.
Fieldpiece HS33 Expandable Manual Ranging Stick Multimeter for HVAC/R. I carry two of these in my service truck. Just like a spare tire, when I get out away from everything, it’s no time for a break down. The Fieldpiece HS33 gives me the ability to do any aspect of my trade. I can measure motor or element amps, check capacitors, and AC or DC voltages. Even different scales of OHMS for finding shorted windings or grounded conductors in motors or compressors.