Line-Set Length and Lift: Read the Charge Tables Before You Quote
4 min read · from the Cold Mountain Supply counter
Equipment ratings assume a standard line-set length — usually 25 feet. Every foot past that changes the system: more refrigerant, more pressure drop, and past the manufacturer's limits, oil that stops making it back to the compressor.
On rural lots and mountain builds, long runs are normal — the condenser lands where the terrain allows, not where the manual would like. Before quoting, pull the installation manual's line-set table for the exact model: maximum total length, maximum vertical lift, required charge adder per foot, and whether the suction riser needs a different diameter to keep oil moving.
Vertical separation cuts both ways. Outdoor unit below the coil, and the suction riser needs velocity; above it, liquid-line static pressure works against you. The tables handle both cases — the trap is not looking.
Charge adders are printed as ounces per foot of liquid line. Weigh the charge in on long runs rather than chasing subcooling from a factory charge that was never right for the run. It's faster, and it's the number a warranty claim will ask about.
Everything this guide mentions is on the shelf — same-day will-call pickup, wholesale pricing with a contractor account.