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.