Although a different symptom, a few years ago our sea water pump that supplies water to the heat pumps began slowing down and making a different louder sound after a long period of running. When I took it apart I noticed a layer of sodium deposits on the impeller vanes. I scraped these off with a utility knife and it resumed its normal operation. What had happened was that the sodium deposits had forced the impeller to slow down and stop spinning, but the motor was still trying to drive it. Our Little Giant brand motor is not a direct drive unit but uses a spinning magnetic field to turn the impeller. Now I periodically remove the motor for cleaning to ensure trouble free operation. At one point I thought the motor needed replacing, but it still keeps running.

Always remember to turn the sea water pump on and open the sea cock before starting the heat pumps. If you forget, the heat pumps will run, but the condenser will freeze up and damage the system. Plus the system will not deliver the heating or cooling you want.

P.S. The impeller shaft of the Little Giant spins on a Delrin sleeve bearing at each end. These bearings slide into a pump chamber slot. Be sure those are in place before putting the pump back together.

Updated: 11/2014