Circulating Pumps (Circulators)
In forced-hot-water heating systems, circulating pumps (also sometimes called circulators or booster pumps) are used to force the hot water through the piping or tubing. Figure 7-29 illustrates a typical location of one of these pumps on a return line. The operation of
Figure 7-29 Circulating pump is located on the return water line next to the boiler.
The one or more circulating pumps in a hydronic system is controlled by a circulator relay.
Circulating pumps for hot-water heating systems are designed and built to handle a wide range of pumping capacities. They will vary in size from small booster pumps with a 5-gpm capacity to those capable of handling thousands of gallons per minute. Some are field serviceable with replaceable cartridges.
In order to select a suitable pump for a hot-water heating system (i. e., one that will produce maximum flow without overloading the pump motor), it is necessary to match the operating characteristics of the pump correctly to the requirements of the heating system.
The correct location of a pump is crucial to its successful operation. Pump manufacturers will usually give detailed information in their literature on this point. Circulating pumps with mechanical seals are very common in hot-water heating systems.