Traditional Type Hot Water Pump and Circulating Systems  

Traditional hot water circulating systems use a hot water circulating pump to pump hot water from the water heater, through the hot water piping, and on back to the water heater through an additional length of pipe that runs from the furthest fixture back to the water heater.  

This type of hot water circulating system provides nearly instant hot water at the fixtures, but wastes a tremendous amount of energy through both the energy required to operate the hot water pump and the heat energy lost from the piping.

Several methods have been employed to reduce the energy waste associated with hot water pump circulating systems.  

Timers are sometimes placed on the circulating pump so the system shuts the hot water pump off during hours that one one normally uses hot water such as from midnight to 6:00 a. m.

Sometimes the circulating pump is controlled by a temperature sensing circuit that shuts the hot water pump off once the water temperature reaches a pre-set temperature such as !40 degrees and then starts the pump back up when the water temperature in the pipe drops below a second set point such as 110 degrees.  This type of system does little to reduce the energy losses because the lower set point is still high  enough to cause continual large heat losses from the system, and the pump does not contribute nearly as much to the loss as the heat loss itself.