Selection of an Oberdorfer CENTRIFUGAL or RUBBER IMPELLER type pump as replacement on a marine air conditioner already in service, is dependent upon several factors.
Pumping capacity required: Based upon the total BTU output of the A/C unit. Most manufacturers select pump size (capacity) based upon the following:
4 GPM (or 240 GPH) for each 12,000 BTU ( 1 Ton A/C)
NOTE: One centrifugal pump will often serve as the coolant pump for two, three or even four condenser units on the same boat. Restrictor valves may be used on centrifugal pumps to reduce flow to desired amount - without damage to the pump unit.
Mounting location NON SELF-PRIMING: If pump is to be mounted below the water line and with a flooded suction port, a centrifugal pump is generally preferred. Centrifugal pumps are quiet running, require less amperage, and are less easily damaged by running dry — than are rubber impeller type pumps. However, most centrifugal pumps do not have suction lift capability (must have flooded suction to function).
Mounting location SELF-PRIMING: If pump is to be mounted above the water line, a self priming unit is essential, such as the 300B-1-F26 Centrifugal above, or Rubber impeller type pumps