Piping connections
The outdoor condensing unit must be connected to the
indoor evaporator coil using field supplied refrigerant
grade (ACR) copper tubing that is internally clean and
dry. Units must be installed only with the tubing sizes for
approved system combinations as specified in the Tabular
Data Sheet. The charge given is applicable for total tubing
lengths up to 15 ft (4.6 m). Refer to the Piping Application
Guide (P/N 24077) for installing tubing of longer lengths
and elevation differences.
NOTICE
Using a larger than specified line size could result in
oil return problems. Using too small a line will result
in loss of capacity and other problems caused by
insufficient refrigerant flow. Slope horizontal vapor
lines at least 1 in. (2.5 cm) every 20 ft (6.1 m) toward
the outdoor unit to facilitate proper oil return. If more
than the 80 ft line length is necessary, facilitate proper
refrigerant velocity with adjusted line diameter in
accordance with the Piping Application Guide (P/N
24077).
CAUTION
This system uses R-410A refrigerant, which operates
at higher pressures than R-22. No other refrigerant
may be used in this system. Gauge sets, hoses,
refrigerant containers, and the recovery system must
be designed to handle R-410A. If you are unsure,
consult the equipment manufacturer.
WARNING
Never install a suction-line filter-drier in the liquid line
of an R-410A system. Failure to follow this warning
can cause a fire, injury or death.
Precautions during line installation
• Install the lines with as few bends as possible. Care
must be taken not to damage the couplings or kink
the tubing. Use clean hard drawn copper tubing
where no appreciable amount of bending around
obstruction is necessary. If soft copper must be
used, care must be taken to avoid sharp bends,
which may cause a restriction.
• The lines must be installed so that they do not
obstruct service access to the coil, air handling
system, or filter.
• Care must also be taken to isolate the refrigerant
lines to minimize noise transmission from the
equipment to the structure.
• The vapor line must be insulated with a minimum
of 3/8 in. foam rubber insulation (Armaflex or
equivalent). Liquid lines that are exposed to direct
sunlight, high temperatures, or excessive humidity
must also be insulated.
• Tape and suspend the refrigerant lines as shown in
Figure 5. Do not allow tube metal-to-metal contact.
• Use PVC piping as a conduit for all underground
installations as shown in Figure 6. Buried lines must
be kept as short as possible to minimize the build
up of liquid refrigerant in the vapor line during long
periods of shutdown.
Figure 5: Installation of vapor line
Figure 6: Underground installation
• Pack fiberglass insulation and a sealing material
such as permagum around refrigerant lines where
they penetrate a wall to reduce vibration and to
retain some flexibility.
• For systems with total line length exceeding 75 ft
(22.86 m), refer to the Piping Application Guide (P/
N 24077) for vapor and liquid line sizing, calibration
of liquid line pressure loss or gain, determination
of vapor line velocity, elevation limitations, TXV
connections, system charging or traps.
R-410A Outdoor Split-System Air Conditioning 9
Johnson Controls Ducted Systems
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