The condensate drain line connects to the mechanical unit drain pan using type DWV copper tubing with wrought copper fittings sized at least as large as the pan nipple. A trap is formed with a vertical drop of two to four inches minimum to maximum. A vent with a capped end is installed upstream of the trap. All interior condensate drain piping requires insulation. A sizing table based on Table 814.3 of the California Plumbing Code specifies minimum pipe diameters for equipment capacities up to forty tons.
(Tons) DRAIN SIZE Up to 20 21-40 3/4" 1" TABLE 814.3 (CPC 2016) EQUIPMENT CAPACITY MIN. PIPE ALL INTERIOR CONDENSATE CAP NOTE: MINIMUM. (TYPE "DWV" COPPER CONDENSATE DRAIN LINE 3/4" TUBING WITH WROUGHT COPPER FITTING.) 2"MIN.- 4"MAX. TRAP MECHANICAL UNIT DRAIN LINE SHALL BE AT LEAST THE SAME SIZE AS THE NIPPLE ON THE PAN. DRAIN PIPING SHALL BE INSULATED. VENT
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