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Refrigeration Piping And Line Sizing
Refrigeration Piping And Line Sizing
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
refrigerant pipe size should be selected from the tables in Refrigeration System Installation Manual, Part
Number 25001201. 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:
(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 (ACR) copper tubing, properly sealed against contamination.
(c) Suction lines should slope 1/4” per 10 feet towards the compressor (in direction of flow).
(d) Suitable P-type oil traps should be located at the base of each suction riser 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 of 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) Wrap expansion valves with wet rags during brazing to the liquid line.
CAUTION: If the temperature gets too high, these components may be damaged. Heat absorbing
compounds or wet rags must be used to protect the expansion valve when brazing to the refrigerant
piping/line connections, and the suction line sensor must be removed per above instructions.
(j) Do not use “bull head” tees. This will cause oil return problems and can cause poor performance.
(k) If isolation valves are installed at the evaporator, full port ball valves should be used.