SERVICING
47 Rev 1
EQUIVALENT LENGTH IN FEET
SUCTION LINE ELBOWS
Fitting Size
I.D. Inches
Sweat, Copper
3/8
1/2
5/8
3/4
7/8
1-1/8
90° Short Radius
1.2
1.4
1.5
1.7
2.0
2.3
90° Long Radius
0.8
0.9
1.0
1.5
1.7
1.6
45°
0.4
0.5
0.6
0.7
0.8
1.0
EXAMPLE:
One 7/8" 90° short radius copper sweat ell is
equal to the resistance of two feet of 7/8" O.D. straight pipe.
To obtain the total equivalent length, add length of straight
pipe to equivalent length of fittings.
NOTE:
The outdoor unit's refrigerant holding charge is for
the matched indoor coil plus 25 feet (15 feet for VCA/B units)
of liquid line. If the piping run is longer than 25 feet (15 feet
for VCA/B units), additional refrigerant may be needed
depending on the indoor coil that is used. The following
charge correction chart
REFRIGERANT LINES IN EXCESS OF 50 FEET
NOTE: Long line sets apply to straight cooling (AC) only.
Heat Pumps are not rated for line sets in excess of 50 feet.
It is always best to keep refrigerant lines to 30 feet or less,
however this is not always possible. The following informa-
tion should be used to size refrigerant lines in excess of 50
feet.
1. Sketch the system and determine the number of traps
required. Traps are required only if the condensing unit
is above the evaporator coil. Traps are only necessary
in the suction line.
SUCTION LINE TRAPS
CONDENSER UNIT ABOVE EVAPORATOR
VERTICAL LIFT (FEET)
TRAPS REQUIRED
0 - 5
0
6 - 19
1
20 - 39
2
40 - 59
3
The first trap goes at the outlet of the evaporator coil. The
remaining traps go halfway up the riser (2 traps total), or 1/
3 and 2/3 the way up the riser (3 traps total).
2. Estimate the effective length of pipe. Remember, each
trap will have a substantial equivalent length. The
suction line effective length could therefore be consider-
ably greater than the liquid line effective length.
3. Size the suction line per the Suction Line Sizing Chart.
3 Purge all remaining components with dry nitrogen or
carbon dioxide until clean.
4. Install new components including liquid liner drier.
5. Install suction line drier.
6. Braze all joints, leak test, evacuate, and recharge sys-
tem.
7. Start up the unit and record the pressure drop across the
clean-up drier.
8. Continue to run the system for a minimum of twelve (12)
hours and recheck the pressure drop across the drier.
Pressure drop should not exceed 6 - 8 PSIG.
9. Continue to run the system for several days repeatedly
checking pressure drop across the suction line drier. If
the pressure drop never exceeds the 6 - 8 PSIG, the drier
must be adequate and is trapping the contaminants and
it is permissible to leave it in the system; however, the
recommended procedure is to remove the suction line
filter from the system after clean-up is complete. Re-
member, any suction line loss equates directly to a
corresponding capacity loss.
10. If the pressure drop becomes greater, then it must be
replaced and steps 5 through 9 repeated until it does not
exceed 6 - 8 PSIG.
NOTICE:
Regardless, the cause for burnout must be deter-
mined and corrected before the new compressor is started.
S-120 REFRIGERANT PIPING
The piping of a refrigeration system is very important in
relation to system capacity, proper oil return to compressor,
pumping rate of compressor and cooling performance of the
evaporator.
The maximum length of tubing to be used with a remote Heat
Pump system is 50 feet; this includes a minimum of turns
with a maximum permissible rise of 20 feet for the liquid line.
1. All horizontal suction line runs must be pitched towards
the compressor (one inch per ten feet). This aids the
return of the oil to the compressor.
2. Avoid long running traps in horizontal suction line.
3. The liquid line must not be attached to an uninsulated
suction line.
4. If the liquid line is routed through an area which has an
ambient higher than 120°F., then that portion of the liquid
line has to be insulated.
5. Suction line sizes should allow for sufficient internal line
velocity (approximately 1500 FPM) to return oil to the
compressor. An oil trap by the indoor coil is necessary
to aid in oil return when the outdoor unit is located above
the indoor coil.
6. In sizing refrigeration piping determine the number of
90° and 45° elbows required and add their equivalent
lengths to the length of straight pipe. Find the equivalent
length of fittings in the following table:
