R-Pro › Field cases › Air conditioning
AC Drain / Refrigerant Pipe Sweating — Inadequate Insulation
Likely causes
Causes — insulation thickness, joints, UV damage
Check: Surface sweat = insulation too thin/damaged. Measure thickness (residential ≥12.7 mm). Joints = no gaps/cracks. UV exposure = check outdoor sections for discoloration/cracks. Common on gas (suction) line = surface <5°C + outdoor >80% RH.
What to do: Add insulation or replace with thicker (19 mm) at sweat zones. Joints = seal with elastomer-compatible adhesive. UV damage = use UV-rated insulation or aluminum jacket. Outdoor sections = inspect/replace every 5 years.
Condensation = #1 cause of ceiling rot/mold disputes. Gas line sweat is a workmanship issue 90% of the time. Skimping on insulation = 10× cost in disputes within 5 years. Size insulation to local climate.
All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.
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