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" every 20 feet toward the
outdoor unit to facilitate proper oil return.
The lines should be installed so that they will not obstruct
service access to the coil, air handling system or filter.
Install the lines with as few bends as possible. Care must be
taken not to damage the couplings or kink the tubing.
Care must also be used to isolate the refrigerant lines to minimize
noise transmission from the equipment to the structure.
Tape and suspend the refrigerant lines as shown. DO NOT
allow metal-to metal contact. See Figure 4.
Use PVC piping as a conduit for all underground installations
as shown in Figure 5. Buried lines should be kept as short as
possible to minimize the build up of liquid refrigerant in the
vapor line during long periods of shutdown.
Pack fiber glass insulation and a sealing material such as
permagum around refrigerant lines where they penetrate a wall
to reduce vibration and to retain some flexibility.
Do not install a filter drier since one is factory installed in every
outdoor unit.
Insulate all vapor lines with a minimum 1/2" foam rubber. Liquid
lines that will be exposed to direct sunlight and/or high tem-
peratures must also be insulated.
NOTE: Some units do not have crankcase heaters (See Table
1). A crankcase heater must be added to these units
when the refrigerant line piping exceeds 50 feet.
See Form 690.01-AD1V for additional piping recommendations.
SYSTEM CONNECTIONS
The outdoor units have re-usable service valves on both the
liquid and vapor connections. The total system refrigerant
charge is retained within the outdoor unit during shipping and
installation. The re-usable service valves are provided to
evacuate and charge per this instruction.
Serious service problems can be avoided by taking adequate
precautions to assure an internally clean and dry system.
Always use refrigerant-grade copper tubing that is internally
clean and dry for refrigerant lines. Use clean hard drawn copper
tubing where no appreciable amount of bending around ob-
struction is necessary. If soft copper must be used, care must
be taken to avoid sharp bends which may cause a restriction.
The vapor line must be insulated with a minimum of 1/2 inch
insulation (Arm-A-Flex or equivalent).
CAUTION: Dry nitrogen should always be supplied through the
tubing while it is being brazed, because the tempera-
ture required is high enough to cause oxidation of the
copper unless an inert atmosphere is provided. The
flow of dry nitrogen should continue until the joint has
cooled. Always use a pressure regulator and safety
valve to insure that only low pressure dry nitrogen is
introduced into the tubing. Only a small flow is nec-
essary to displace air and prevent oxidation.
All outdoor unit and evaporator coil connections are copper-to-
copper and should be brazed with a phosphorous-copper alloy
material such as Silfos-5 or equivalent. DO NOT use soft
solder.
BASE VALVE CONNECTION PRECAUTIONS
Precautions should be taken to prevent heat damage to the
fitting by wrapping a wet rag around it as shown in Figure 6.
Also, protect all painted surfaces and insulation during brazing.
After brazing - cool joint with wet rag.
FIGURE 4 - TUBING HANGER
LIQUID
LINE
TAPE
SHEET
METAL
HANGER
INSULATED
VAPOR LINE
TO INDOOR COIL
TO OUTDOOR UNIT
LIQUID LINE
CAP
PVC
CONDUIT
INSULATED
VAPOR LINE
FIGURE 5 - UNDERGROUND INSTALLATION
550.36-N2Y
4
Unitary Products Group
