Is There a Minimum Required Length for a Line Set? - Ask the Expert Episode 201

Today's question comes from Abe. "Hey Dan, is there a minimum required length for a line set? I only need seven feet. I wasn't sure if you needed a certain amount of coolant between the units?"

So, he's talking about the copper line set that you would find between a central heating and air condenser, which is the outside part of the system, and an interior air handler. He could also be talking about a ductless mini split with a similar setup, the condenser outside and the air handler inside. Between those, you have two refrigerant lines called the line set.

The answer to your question is yes. Sort of.

So, the condenser is going to be charged most of the time for a certain amount. The manufacturer may think, well, most people are going to have about twenty feet of line between the condenser and the air handler. So, they will charge the unit for that amount. Which means technically there is a minimum required length for a line set, however, if you need less than what they charged it for, you might have to take some out.

But that's not a big deal. Any good technician can take out refrigerant or add it. That's not uncommon when you're installing a split system. You might have to add a little refrigerant, you might have to take some out.

As far as a truly minimum length, I mean, not really. For instance if you've got a package unit, and the condenser coil and your evaporator coil are right next to each other, so it's not like you have to have like ten feet or something for it to work. The minimum required length for a line set just depends on your unit.

Have more questions? Just ask them in the comments below or on Facebook or on Twitter.

4 comments (view/add)
  • Kurt Nienhusser
    Kurt Nienhusser
    Posted on 2/25/2020

    Hi Dan,
    Can you pealse point out the pros and the cons of installing a MINI SPLIT system in the crawl space?
    Thanks and I hope to hear from you soon!

  • Kyle
    Kyle from Ingrams
    Posted on 2/26/2020

    By 'in the crawl space' do you mean putting the condenser in the crawl space?

  • Adam Alexander
    Adam Alexander
    Posted on 6/11/2020

    Hi Dan,

    Like Abe, I only need about 6 feet of copper line for my mini-split ac install. It's a Gree 12,000 BTU unit and comes pre-charged with 47.6 oz. of R410A refirgerant for a minimum line set of 10' and a maximum line set of 25'. The manufacturer's instructions say to add .21 oz of refrigerant for every extra foot of line set beyond 25', but there is no mention of how much refrigerant to remove if the line set is less than 10'. Do you know how I can determine how much refrigerant to remove if my line set is 6 feet?

    Thank you,

    Adam Alexander

  • Kyle
    Kyle from Ingrams
    Posted on 6/12/2020

    Hi, Adam. My understanding that Gree does not recommend line sets shorter than 10 feet. However, if you choose to use only use 6', then the proper adjustment would be the same as for additions, but in reverse. The 4 ft would be removing 0.84 oz and less than an oz would be insignificant to the operation of the system.

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