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Resumen del manual
6 Condensing Unit Rigging Figure 3. Condensing Unit Rigging Adequate rigging measures must be taken to support unit weight and to protect the unit from damage during unloading and placement process. Rigging holes have been provided in legs and under the unit compressor compartment frame to assist. Rigging Holes Spreader bars may be used to protect unit from damage. 7 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. 8 9 Figure 5. Drain Line Refrigeration Piping Suction Lines NOTE: If the suction line must rise to the point higher than the suction connection on the evaporator, a suction line trap at the outlet of the evaporator must be provided. Horizontal suction lines should slope away from the evaporator toward the compressor at the rate of 1/4’ per 10 feet for good oil return. When multiple evaporators are connected in series using a common suction line, the branch suction lines must enter the top of the common suction line. Suction lines that are outside of refrigerated space must be insulated. See “Line Insulation” for more information. Suction Line Risers NOTE: To provide proper oil return, a suction trap must be provided at the base of all suction risers. Prefabricated wrought copper traps are available, or a trap can be made by using two street ells and one regular ell. The suction trap must be the same size as the suction line. For long vertical risers, additional traps may be necessary. Generally, one trap is recommended for each length of pipe (approximately 20 feet) to insure proper oil movement. See Figure 4 below for methods of constructing proper suction line P-traps. Condensate Drain Lines Copper drain lines should be used and properly protected from freezing. In running drain lines, provide a minimum of 4 inches per foot pitch for proper drainage. Drain lines should be at least as large as the evaporator drain connection. All plumbing connections should be made in accordance with local plumbing codes. All condensate drain lines must be trapped, and run to an open drain. They must never be connected directly to the sewer systems. Traps in the drain line must be located in a warm ambient. We recommend a trap on all evaporators. Traps located outside, or extensive outside runs of drain line must be wrapped with a drain line heater. The heater should be connected so that it is continuously on. It is recommended that the drain line be insulated to prevent heat loss. A heat input of 20 watts per lineal foot of drain line for 0.F (-18°C) room applications and 30 watts per lineal foot for -20°F (-29°C)...