York YUHC 18, Service Manual, Page: 36 / 49

2. Refrigerant pipe connecting
(1) Piping sizes
Model (Btu/h) Liquid (mm/inch) Gas (mm/inch)
18,000 6.35(1/4) 12.7(1/2)
24,000 9.53(3/8) 16.0(5/8)
30,000~60,000. 12.7(1/2) 19.0(3/4)
(2) Piping connection
1). Measure the necessary length of the connecting pipe, and make it by the following way.
a. Connect the indoor unit at first, then the outdoor unit.
Bend the tubing in proper way. Do not harm them.
CAUTIONS
Daub the surfaces of the flare pipe and the joint nuts with frozen oil, and wrench it for 3~4 rounds
With hands before fasten the flare nuts.
Be sure to use two wrenches simultaneously when you connect or disconnect the pipes.
Tubing size Torque
6.35 1420~1720N.cm(144~176kgf.cm)
9.52 3270~3990N.cm(333~407kgf.cm)
12.7 4950~6030N.cm(504~616kgf.cm)
16 6180~7540N.cm(630~770kgf.cm)
19 9720~11860N.cm(990~12106kgf.cm)
b. The stop value of the outdoor unit should be closed absolutely (as original state). Every time you connect it,
first loosen the nuts at the part of stop value, then connect the flare pipe immediately (in 5 minutes). If the nuts
have been loosened for a long time, dusts and other impurities may enter the pipe system and may cause
malfunction later. So please expel the air out of the pipe with refrigerant before connection.
c. Expel the air after connecting the refrigerant pipe with the indoor unit and the outdoor unit. Then fasten the
nuts at the repair-points.
2) Locate The Pipe
a. Drill a hole in the wall (suitable just for the size of the wall conduit), then set on the fittings such as the wall
conduit and its cover.
b. Bind the connecting pipe and the cables together tightly with binding tapes. Do not let air in, which will cause
water leakage by condensation.
c. Pass the bound connecting pipe through the wall conduit from outside. Be careful of the pipe allocation to do
no damage to the tubing.
3) Connect the pipes.
4) Then, open the stem of stop values of the outdoor unit to make the refrigerant pipe connecting the indoor unit
with the outdoor unit in fluent flow.
5) Be sure of no leakage by checking it with leak detector or soap water.
6) Cover the joint of the connecting pipe to the indoor unit with the soundproof / insulating sheath (fittings), and
bind it well with the tapes to prevent leakage.