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REFRIGERANT PIPING
GENERAL GUIDELINES
Many service problems can be avoided by taking adequate
precautions to provide an internally clean and dry system and
by using procedures and materials that conform with estab-
lished standards.
Useharddrawncopper tubingwhereno appreciableamountof
bending around pipes or other obstructions is necessary. Use
long radius ells wherever possible with one exception—short
radius ells for the traps in all suction risers. If soft copper is
used, care should be taken to avoid sharp bends which may
cause a restriction.
Pack fiber glass insulation and a sealing material such as per-
magum around refrigerant lines where they penetrate a wall to
reduce vibrations and to retain some flexibility.
Support all refrigerant lines at minimum intervals with suitable
hangers, brackets or clamps.
Braze all copper to copper joints with Silfos-5 or equivalent
brazing material. Do not use soft solder.
Insulate allsuction lines witha minimum of 1/2"ARMAFLEX or
equal. Liquid lines exposed to direct sunlight and/or high tem
-
peratures must also be insulated.
Never solder suction and liquid lines together. They can be
tapedtogetherforconvenience andsupportpurposes, butthey
must be completely insulated from each other.
Afilter-drierMUST beinstalled inthe liquidline ofeverysystem
to prevent dirt and moisture from damaging the system. A
properly-sized filter-drier is shipped with each condensing unit
forfieldinstallationnear theevaporatorcoil. Thefilter-drierand
is taped to the top of the compressor.
NOTE: Installing a filter-drier does not eliminate the need for
the proper evacuation of a system before it is
charged.
A moisture indicating sight-glass may be field installed in the
liquid line(s) between the filter-drier and the evaporator coil.
The moisture indicating sight-glass can be used to check for
excess moisture in the system or used as a visual means to
verify refrigerant charge.
LINE SIZING
When sizing refrigerant lines for a split-system air conditioner,
check the following:
1. Suction line pressure drop due to friction
2. Liquid line pressure drop due to friction
3. Suction line velocity for oil return, and
4. Liquid line pressure drop due to static head.
NOTE: Never base refrigerant line sizes on the O.D. of the
suction and liquid connections on the unit.
Tables 4and 5 list friction losses for both the suctionand liquid
lines on the system. Table 6 shows the amount of refrigerant
charge required per foot of refrigerant line.
Whentheevaporatorcoilisbelowthecondensingunit,thesuc-
tion linemust be sizedfor both pressuredrop andfor oil return.
For certain piping arrangements, different suction line sizes
may have to be used. The velocity of the suction gas must al
-
ways be great enough to carry oil back to the compressor.
When the condensing unit is below the evaporator coil, the liq
-
uidline mustbe designedfor thepressure dropdue toboth fric
-
tion lossand vertical rise. Ifthe total pressuredrop exceeds 40
psi, some refrigerant may flash before it reaches the thermal
expansion valve. This flashing will not only cause erratic valve
operation and poor system performance, but could also dam
-
age the expansion valve.
SERVICE VALVES
These condensing units have service valves on both the com
-
pressor suction connection and the liquid line leaving the con
-
denser coil.
The liquid and suction lineservice valves are shipped from the
factoryfront-seatedand closedwith thevalvestem inthe maxi
-
mum clockwise position.
Bothoftheservice valveshavea1/4" maleflareaccessport for
evacuating, charging and pressure checking the system.
NOTE: Never remove a cap from an access port unless the
valve is fully back-seated with its valve stem in the
maximum counter-clockwise position because the re
-
frigerant charge will be lost. ALWAYS USE A RE
-
FRIGERATION VALVE WRENCH TO OPEN AND
CLOSE THESE SERVICE VALVES.
035-15407-002-B-0404
Unitary Products Group 7
FIG. 6 - FOUR POINT LOADS
)
*
+
,
HCE090
)
,
+
*
HCE120 & 150
UNIT
4- POINT LOAD (LBS)
TOTAL A B C D
120 430 90 114 127 99
150 510 111 152 143 104