Controlling hot water recirculation

Abstract

The present disclosure provides for a recirculating flow controller that is operably coupled to a flow switch and to a recirculation pump. The recirculating flow controller determines that hot water has begun to flow by way of the connection with the flow switch. In response, the recirculating flow controller activates the recirculation pump to circulate hot water from a water heater. The recirculating flow controller can activate the recirculation pump for a predetermined duration. The flow switch can be configured to sense flow in a hot water line connected to a water heater. The flow switch can be activated by turning on any hot water faucet connected to the water heater.

1 . A hot water recirculation system comprising:
 a hot water line coupled to a fixture to deliver hot water to the fixture;   a cold water line coupled to the fixture to deliver cold water to the fixture;   a crossover valve that fluidly couples the hot water line to the cold water line at the fixture so that water can flow between the hot water line and the cold water line without water flowing from the fixture;   a flow switch operably coupled to the hot water line and configured to change state responsive to a flow rate of water through the hot water line;   a recirculation pump configured to circulate water through the hot water line, the crossover valve, and the cold water line, the hot water line and the cold water line in fluidic communication with to a water heater, the recirculation pump installed at the water heater; and   a recirculating flow controller operably coupled to the flow switch and to the recirculation pump, the recirculating flow controller configured to activate the recirculation pump responsive to the flow switch changing state to deliver hot water to the fixture,   wherein the flow switch changes state responsive to the fixture turning on hot water and then turning off hot water to cause hot water to be delivered to the fixture.   
     
     
         2 . The hot water recirculation system of  claim 1 , wherein the recirculating flow controller is configured to activate a recirculation program responsive to the flow switch changing state. 
     
     
         3 . The hot water recirculation system of  claim 2 , wherein the recirculation program includes activating the recirculation pump after a programmed amount of time. 
     
     
         4 . The hot water recirculation system of  claim 2 , wherein the recirculation program includes deactivating the recirculation pump after a programmed amount of time. 
     
     
         5 . The hot water recirculation system of  claim 2 , wherein the recirculation program includes running the recirculation pump for a programmed amount of time. 
     
     
         6 . The hot water recirculation system of  claim 1 , wherein a first state of the flow switch indicates a flow rate through the hot water line above a first threshold and a second state of the flow switch indicates a flow rate through the hot water line under a second threshold. 
     
     
         7 . The hot water recirculation system of  claim 6 , wherein the recirculation flow controller does not deactivate the recirculation pump responsive to the flow switch changing state from the first state to the second state. 
     
     
         8 . A method for recirculating hot water, the method comprising:
 installing a crossover valve at a fixture, the crossover valve configured to provide a flow path for water from a hot water line to a cold water line without leaving the fixture;   sensing, with a flow sensor coupled to the hot water line, a flow rate of water through the hot water line that delivers water to a fixture, the flow sensor configured to change state responsive to a flow rate of water through the hot water line;   responsive to the flow rate of water through the hot water line exceeding a flow rate threshold, activating a recirculation pump coupled to a water recirculation system that includes the hot water line, the cold water line, the crossover valve, and a water heater to deliver hot water to the fixture, the recirculation pump installed at the water heater; and   deactivating the recirculation pump according to a recirculation program,   wherein the flow rate threshold is configured to be exceeded responsive to the fixture turning on hot water and then turning off hot water, thereby causing hot water to be delivered to the fixture.   
     
     
         9 . The method of  claim 8 , wherein the recirculation program includes a timed duration for running the recirculation pump. 
     
     
         10 . The method of  claim 9 , wherein the timed duration is greater than 1 minute. 
     
     
         11 . The method of  claim 10 , wherein the timed duration is less than 10 minutes. 
     
     
         12 . The method of  claim 8 , wherein the recirculation program includes a predetermined amount of time to wait between sensing the flow of water and activating the recirculation pump. 
     
     
         13 . The method of  claim 8  further comprising:
 presenting, by the flow switch, a first state responsive to the flow rate through the hot water line above a first threshold; and 
 presenting, by the flow switch, a second state responsive to the flow rate through the hot water line under a second threshold. 
 
     
     
         14 . The method of  claim 13 , wherein the recirculation pump is not deactivated responsive to the flow switch changing state from the first state to the second state.