Line Set
The insulated copper refrigerant lines (plus control wiring and a condensate drain) connecting an outdoor unit to its indoor unit or heads. On ductless installs the bundle needs only a three-inch wall opening — the reason mini-splits retrofit so cleanly into finished homes.
The longer answer
Line sets have physics: manufacturer limits on length and vertical rise per circuit. A far bedroom is usually fine; a detached studio at the property line may want its own single-zone system instead — both are normal design outcomes.
On replacements, existing line sets can sometimes be reused when sizes match the new equipment and the runs pressure-test sound (flushed per manufacturer procedure). It saves real money where legitimate — and it's a corner worth confirming explicitly in any bid rather than assuming.
Guides that use this term
Where this decision happens
Nearby in the glossary
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