10
TWINNING MDC PORTS
For indoor units with capacities greater than 54 kBtu/h, two
MDC ports must be twinned using the Y-joint to create a single
port. The two ports to be paired should be next to each other.
Refer to Y-joint “G” in the piping layout shown in Fig. 10. The
first port of the pair should have an odd number, and second
port should be the next sequential even number. For example: 1
and 2, 3 and 4, or 5 and 6 and so on. You cannot pair 2 and 3, 4
and 5, or 6 and 7.
Table 8 shows the pipe diameters to use when connecting
the MDC and the Y-joint.
Table 8 — Piping Between the MDC and Y-Joint
PIPING BETWEEN MDC AND SUB MDC — Three pipes
are used to connect the main MDC and the sub MDC.
Selection of the Sub MDC should follow the requirements of
Table 9. For connecting the sub MDC to main MDC, use the
high pressure, low pressure, and liquid pipes as shown in Figs.
11 and 12.
Table 9 —Sub MDC Selection
CAUTION
Connecting an indoor unit with a capacity greater than
54 kBtu/h may result in damage to equipment.
TOTAL CAPACITY OF
INDOOR UNITS
(kBtu/h)
LIQUID PIPE
(in.)
GAS PIPE
(in.)
> 54
3
/
8
5
/
8
Fig. 10 — Twinning Ports with the Y-Joint
LEGEND
G
— Y-Joint
MDC
G
G
MDC
G
G
CORRECT
INCORRECT
MAIN MDC MODEL
SUB MDC UNIT
006
006
008
006
008
010
006
008
010
016/016L
006
008
010
016
b
c
a
a
b
d
e
a
f
