SERVICING
NOTE: At least twelve (12) inches of the suction line immediately out of the compressor stub must be discarded due to burned residue and contaminates.
1.Remove compressor discharge line strainer.
2.Remove the liquid line drier and expansion valve.
3Purge all remaining components with dry nitrogen or carbon dioxide until clean.
4.Install new components including liquid line drier.
5.Braze all joints, leak test, evacuate, and recharge sys- tem.
6.Start up the unit and record the pressure drop across the drier.
7.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 PSIG.
8.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 PSIG, the drier has trapped the contaminants. Remove the suction line drier from the system.
9.If the pressure drop becomes greater, then it must be replaced and steps 5 through 9 repeated until it does not exceed 6 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.
POE oils maintain a consistent viscosity over a large tem- perature range which aids in the oil return to the compressor; however, there will be some installations which require oil return traps. These installations should be avoided whenever possible, as adding oil traps to the refrigerant lines also increases the opportunity for debris and moisture to be introduced into the system. Avoid long running traps in horizontal suction line.
LONG LINE SET APPLICATION R-410A
This long line set application guideline applies to all AHRI listed
Accessories for lines greater than 80 feet:
1.Crankcase Heater- a long line set application can critically increase the charge level needed for a system. As a result, the system is very prone to refrigerant migration during its
2.For all line set applications over 80 feet a TXV is recom- mended. The subcooling should be 6º ± 2º.
3.Hard Start Assist- increased charge level in long line applications can require extra work from the compressor at
4.Liquid Line Solenoid - a long line set application can critically increase the charge level needed for a system. As a result, the system is very prone to refrigerant migration during its
Tube Sizing:
1.In long line applications, the “equivalent line length” is the sum of the straight length portions of the suction line plus losses (in equivalent length) from 45 and 90 degree bends. Select the proper suction tube size based on equivalent length of the suction line (see Tables 4 & 5) and recalculated system capacity.
Equivalent length =
Length horizontal
+Length vertical
+Losses from bends (see Tables 4 & 5)
Example using ¾” elbow:
150 feet of straight tubing + (four short radius elbows x 1.7) + (2 long radius elbows x 1.5) = 150 + 3.4 +3 =
156.4equivalent feet.
2.For any residential split system installed with a long line set, 3/8" liquid line size must be used. Limiting the liquid line size to 3/8" is critical since an increased refrigerant charge level from having a larger liquid line could possibly shorten a compressor’s
3.Single Stage Condensing Unit: The maximum length of tubing must not exceed 150 feet.
•80 feet is the maximum recommended vertical difference between the condenser and evaporator when the evapo- rator is above the condenser. Equivalent length is not to exceed 150 feet.
•Theverticaldifferencebetweenthecondenserandevapo- rator when the evaporator is below the condenser can approach 150 feet, as long as the equivalent length does not exceed 150 feet.
•The distance between the condenser and evaporator in a completely horizontal installation in which the indoor and outdoor unit do not differ more than 10 feet in vertical distance from each other can approach 150 feet, as long as the equivalent length does not exceed 150 feet.
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