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Phase Loss Monitor
The combination phase sequence and loss monitor relay protects the system against phase loss (single phasing), phase reversal (improper sequence) and low voltage (brownout).
When phase sequence is correct and full line voltage is present on all three phases, the relay is energized as the normal condition indicator light glows.
NOTE: If compressor fails to operate and the normal condition indicator light on the phase monitor does not glow, then the supplied electrical current is not in phase with the monitor. This problem is easily corrected by the following steps:
1. Turn power off at disconnect switch.
2. Swap any two of the three power input wires.
3. Turn power on. Indicator light should glow and compressor should start.
4. Observe motors for correct rotation.
Recommended Refrigerant Piping Practices
The system as supplied by Heatcraft Refrigeration Products, was thoroughly cleaned and dehydrated at the factory. Foreign matter may enter the system by way of the evaporator to condensing unit piping. Therefore, care must be used during installation of the piping to prevent entrance of foreign matter.
Install all refrigeration system components in accordance with applicable local and national codes and in conformance with good practice required for the proper operation of the system.
The interconnecting pipe size is not necessarily the same size as the stub-out on the condensing unit or the evaporator.
The following procedures should be followed:
Refrigerant Pipe Support
1. Normally, any straight run of tubing must be supported in at least two locations near each end of the run. Long runs require additional supports. The refrigerant lines should be supported and fastened properly. As a guide,
3/8 to 7/8 should be supported every 5 feet; 1-1/8 and
1-3/8 every 7 feet; and 1-5/8 and 2-1/8 every 9 to 10 feet.
2. When changing directions in a run of tubing, no corner should be left unsupported. Supports should be placed a maximum of 2 feet in each direction from the corner.
3. Piping attached to a vibrating object (such as a compressor or compressor base) must be supported in such a manner that will not restrict the movement of the vibrating object. Rigid mounting will fatigue the copper tubing.
4. Do not use short radius ells. Short radius elbows have points of excessive stress concentration and are subject to breakage at these points.
5. Thoroughly inspect all piping after the equipment is in operation and add supports wherever line vibration is significantly greater than most of the other piping.
Extra supports are relatively inexpensive as compared to refrigerant loss.
Figure 4. Example of Pipe Support
(a) Do not leave dehydrated compressors or filter-driers on condensing units open to the atmosphere any longer than is absolutely necessary.
(b) Use only refrigeration grade copper tubing, properly sealed against contamination.
(c) Suction lines should slope 1/4" per 10 feet towards the compressor.
(d) Suitable P-type oil traps should be located at the base of each suction riser of four (4) feet or more to enhance oil return to the compressor.
(e) For desired method of superheat measurement, a pressure tap should be installed in each evaporator suction line in the proximity of the expansion valve bulb.
(f) When brazing refrigerant lines, an inert gas should be passed through the line at low pressure to prevent scaling and oxidation inside the tubing.
Dry nitrogen is preferred.
(g) Use only a suitable silver solder alloy on suction and liquid lines.
(h) Limit the soldering paste or flux to the minimum required to prevent contamination of the solder joint internally. Flux only the male portion of the connection, never the female. After brazing, remove excess flux.
(i) If isolation valves are installed at the evaporator, full port ball valves should be used.
Figure 5. Condensing Unit / Compressor to Wall Support.
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