Refrigerator Troubleshooting Diagram

Archive for the ‘Condenser’ Category

A/C Shell and Tube Condenser

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Shell and Tube Condenser

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September 13th, 2011 at 4:16 am

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Double-Pipe Water-Cooled Condenser

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Double-pipe water-cooled condenser

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September 6th, 2011 at 3:42 am

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HVAC Air Cooled Condenser

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HVAC Air Cooled condenser

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September 6th, 2011 at 3:34 am

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Outdoor Condensing Units

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In some applications, a number of units are not needed and a mechanical center is not called for. Then an outdoor condensing unit is used (see Figure 8-21). These units come as a factory package. They are easily hooked up with the refrigeration unit inside the store or office or factory. They may be located on the roof or on a slab outside the building they are serving. Possible loss of head-pressure control (caused by the wind) is prevented by enclosing the underside of the unit.

It has been generally believed that it is necessary to artificially maintain summer-like conditions on the condenser of refrigeration systems. This was because a large pressure difference had to exist between the high and low sides. It has been found, however, that if adequate measures are taken to ensure a solid column of liquid refrigerant to the expansion valves of cases located inside the building, no problems will be experienced. The advantage is in lowering the condenser temperature. This makes the compressor run more efficiently, saving on energy costs.

Liquid lines exposed to temperatures above 60◦F (15.6◦C) must be insulated. This also applies to any lines that run overhead and to some lines close to the floor.

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February 14th, 2011 at 12:37 am

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Cleaning Evaporative Condensers

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The method used in protecting the coils in evaporative condensers from scale and other deposits and removing the deposits after they have formed depends on the characteristics of the water in the particular location. If the water at the installation site is very hard, solids will form between the coil fins. The first step to take for the prevention of this scale formation is to provide ample overflow. This minimizes the concentration of solids in the water and prevents the formation of slime. If the water composition is such that scale will form readily, the water should be chemically treated. For this treatment, a sample of the water should be sent to a competent water treatment organization that will make a complete analysis and will recommend the proper chemical solution to use.

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February 14th, 2011 at 12:34 am

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Condenser Maintenance

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The method of cleaning condenser water tubes will depend on the water characteristics in the locality in which the condensing unit is installed, and on the construction of the condenser used. Water has many different impurities, which normally form a hard scale on the walls of the water tubes. This scale is detrimental to condenser performance.

With condensers having removable heads, the scale on the walls of the tubes can be removed by attaching a round steel brush to a rod and working it in and out of the tubes. After the tubes have been cleaned with the brush, flush by running water through them. Some scale deposits are harder to remove than others, and a steel brush may not do the job. There are several different types of tube cleaners on the market for removing hard scale. They may be purchased locally.

When installing the condensing unit, keep in mind that the condensers may need to be cleaned. Allow enough room at the removable head to get a rod long enough to work in and out of the tubes. After cleaning, always use a new condenser head gasket. The simplest method of removing scale and dirt from condenser tubes that are not accessible for mechanical cleaning is with an inhibited acid, which cleans the coils or tubes by chemical action. When the scale deposit is not too great, gravity flow of the acid will provide sufficient cleaning. However, when the deposit is great enough to almost clog the tubes (thus inhibiting gravity flow), forced circulation must be used. Figure 8-17 shows the equipment and connections for circulating the inhibited acid through the condenser using the gravity-flow method. The equipment consists of a crock or wooden bucket for the drain, and a 1-inch steel pipe of sufficient length to make the piping connection. The vent pipe should be installed at the higher connection of the condenser.

Figure 8-18 shows the equipment and connections used when forced circulation may be necessary. When this method is used, a suitable pump will be required to provide pressure. The inhibited solution is stored in a metal tank (not galvanized) with ordinary bronze or copper fly screening to prevent the large pieces of scale or dirt from getting into the pump intake line. In addition, 1-inch steel piping with connections and globe valves are provided, as shown. The vent pipe should be installed at the higher connection of the condenser.

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February 14th, 2011 at 12:32 am

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Cooling-Water Circuits

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In compressors with water jackets and in water-cooled condensers, cooling-water circuits may be in series or parallel. The use of parallel circuits results in a lower pressure drop through the circuit, and may be necessary when the temperature of the cooling water is such that the water temperature rise must be held to a minimum. Figure 8-5 and Figure 8-6 show how to install water lines for series or parallel flow.

Because of occasional damage to condensers by excessive water velocities, it has been found that the water velocity should not exceed 7 feet per second. Thus, to maintain water velocities at acceptable levels, parallel circuiting of the condenser may be necessary. When a water-circulating pump is used, it should be installed so that the condenser is fed from the discharge side of the pump. If the pump is installed on the discharge side of the condenser, the condenser will have a slight vacuum in the water system and the water will be much nearer the boiling point.

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February 14th, 2011 at 12:22 am

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Water-Cooled Condensers

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Used on commercial and larger systems, water-cooled condensers are classified as double-pipe, flooded atmospheric; bleeder shelland-tube, and shell-and-coil. In condensers of this type, the amount and temperature of the water determine the condensing temperature and pressure, and (indirectly) the power required for compression. In locations where water must be conserved or where water is restricted, it is usually necessary to install cooling towers or evaporative condensers. When adequate low-cost condensing water is available, water-cooled condensers are often desirable because of the lower condensing pressures and better head-pressure control.

Water (particularly from underground sources) may be much colder than daytime temperatures. If evaporative cooling towers are used, the condensing water can be cooled to a point closely approaching the ambient wet-bulb temperature, which allows the continuous recirculation of condensing water and reduces water consumption to a minimum. A water-cooled condensing unit is shown in Figure 8-3.

A pressure- or temperature-sensitive modulating water-control valve (such as shown in Figure 8-4) can be used to maintain condensing pressures within the desired range by increasing or decreasing the rate of water flow as necessary.

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February 14th, 2011 at 12:18 am

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Air-Cooled Condensers

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Air-cooled condensers are used universally on smaller refrigerating units, but seldom for capacities in excess of 3 tons of refrigeration. They are equipped for natural draft and fan cooling and are termed according to their construction as plain tubes, finned tubes, plate type, and series or parallel pass. The conventional air-cooled condenser consists of an extended-surface coil across which air is blown by a fan. In operation, hot discharge gas enters the coil at the top. As it is condensed, it flows to a receiver located below the condenser. Figure 8-1 and Figure 8-2 show typical air-cooled condensing units.

Air-cooled condensers should always be located in a well ventilated space. This is how the heated air may escape and be replaced by cooled air. Because of space requirements, air-cooled condensers are normally constructed with a relatively small face with several rows of tubing in depth. As the air is forced through the condenser, it absorbs heat, and the air temperature rises. Therefore, the efficiency of each succeeding row in the coil decreases, although coils up to eight rows in depth are frequently used.

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February 14th, 2011 at 12:12 am

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