Hot Water Recirculation Control Unit and Method

Abstract

A hot water recirculation control unit has a housing, a male wall plug integrated into a first wall of the housing, an electrically-operable power switch, female wall plug integrated into a second wall of the housing, control circuitry including a processor, having an output enabled to switch the electrically-operable power switch, and signal ports enabled to receive signals from two temperature sensors and at least one flow sensor. The control circuitry switches the electrically-operable power switch on or off, providing power to or disconnecting power from the standard female electrical wall plug, based on presence and value of signals received at the one or more input signal ports.

1 . A hot water recirculation control unit, comprising:
 a housing;   a standard male electrical wall plug integrated into a first wall of the housing, the male wall plug connected to hot, neutral and ground electrical conductors in electrical circuitry within the housing;   an electrically-operable power switch in the circuitry of the controller, connected on an input side to the hot electrical conductor;   a standard female electrical wall plug integrated into a second wall of the housing, connected to neutral and ground and to the output terminal of the electrically-operable power switch;   control circuitry including a processor, connected to the electrical conductors, the control circuitry having an output enabled to switch the electrically-operable power switch; and   one or more input signal ports enabled to receive signals from two temperature sensors and at least one flow sensor, the signal ports connected to the control circuitry;   wherein the control circuitry switches the electrically-operable power switch on or off, providing power to or disconnecting power from the standard female electrical wall plug, based on presence and value of signals received at the one or more input signal ports.   
     
     
         2 . The hot water recirculation control unit of  claim 1  wherein the control circuitry switches the electrically-operable power switch on, providing power to the standard female electrical wall plug, in response to a signal that the flow sensor senses positive flow, and a pre-set difference in temperature is sensed between the two temperature sensors. 
     
     
         3 . The hot water recirculation control unit of  claim 2  further comprising a mechanism enabling adjustment of the preset difference in temperature. 
     
     
         4 . The hot water recirculation control unit of  claim 1  further comprising a manual input enabled to switch the electrically-operable power switch on and off. 
     
     
         5 . The hot water recirculation control unit of  claim 2  wherein the control circuitry comprises one or more timing mechanisms for improving reliability of operation. 
     
     
         6 . A hot water recirculation system, comprising:
 a water heating source;   a pipe loop from the water heating source supplying heated water to a plurality of draw points and returning to an input of the hot water heating source;   a cold water supply line to the hot water heating source;   a water pump in the pipe loop after the draw points and before the input to the water heating source;   a flow sensor in the pipe loop to indicate positive flow of water, indicating a draw at one of the plurality of draw points;   a first temperature sensor coupled to the pipe loop near the outlet of the water heating source;   a second temperature sensor coupled to the pipe loop at a point after the plurality of draw points; and   a controller having an electrical power input from a power source, an electrical power output to the water pump, and control circuitry enabled to switch power from the power source to the output to the water pump;   wherein signals from the flow sensor and the first and second temperature sensors are coupled to the control circuitry and the control circuitry switches power from the power source to the power output to the water pump, based on presence and value of signals received from the flow sensor and the temperature sensors.   
     
     
         7 . The hot water recirculation system of  claim 6  wherein the control circuitry switches power to the water pump in response to a signal that the flow sensor senses positive flow, and a pre-set difference in temperature sensed between the two temperature sensors. 
     
     
         8 . The hot water recirculation system of  claim 7  further comprising a mechanism coupled to the control circuitry enabling adjustment of the preset difference in temperature. 
     
     
         9 . The hot water recirculation system of  claim 6  further comprising a manual input to the control circuitry enabled to switch power to the water pump, overriding the control circuitry. 
     
     
         10 . The hot water recirculation system of  claim 6  wherein the control circuitry comprises one or more timing mechanisms for improving reliability of operation. 
     
     
         11 . A hot water recirculation method, comprising:
 providing a pipe loop from a water heating source to a plurality of draw points and returning to an input of the hot water heating source;   providing a cold water supply line to the water heating source;   proving a water pump in the pipe loop after the draw points and before the input to the water heating source;   sensing flow by a flow sensor in the pipe loop to indicate positive flow of water, indicating a draw at one of the plurality of draw points;   sensing a first temperature by a first temperature sensor coupled to the pipe loop near the outlet of the water heating source;   sensing a second temperature by a second temperature sensor coupled to the pipe loop at a point after the plurality of draw points;   monitoring flow indication from the flow sensor and temperatures sensed by the temperature sensors at a controller having an electrical power input from a power source, an electrical power output to the water pump, and control circuitry enabled to switch power from the power source to the output to the water pump; and   switching power from the power source to the power output to the water pump, causing recirculation in the pipe loop, based on presence and value of signals received from the flow sensor and the temperature sensors.   
     
     
         12 . The hot water recirculation method of  claim 11  wherein the control circuitry switches power to the water pump in response to a signal that the flow sensor senses positive flow, and a pre-set difference in temperature sensed between the two temperature sensors. 
     
     
         13 . The hot water recirculation method of  claim 12  further comprising a step for adjusting the preset difference in temperature by a mechanism coupled to the control circuitry. 
     
     
         14 . The hot water recirculation method of  claim 11  further comprising overriding the control circuitry by a manual input to switch power to the water pump. 
     
     
         15 . The hot water recirculation method of  claim 11  wherein the control circuitry comprises one or more timing mechanisms for improving reliability of operation.