System and method for efficient and expedient delivery of hot water

Abstract

A system and method for detecting and anticipating fluid flow in a pipe utilizing a sensor, a processor, and a time base.

1 . A fluid demand detection device comprising: 
 a first pipe for transporting a fluid;    a sensor for sensing a temperature that varies with the temperature of the fluid;    a processor in signal communication with the temperature sensor said processor for evaluating a time rate of temperature change; and,    a current flow in an electric circuit responsive to the time rate of temperature change.    
   
   
       2 . The device of  claim 1  wherein: 
 the processor makes a plurality of temperature measurements corresponding to different times and calculates at least one temperature difference between a first temperature measured at a first time and one or more second temperatures measured at one or more respective second times;    each of the times being bounded by a single preselected time interval; and,    the current flow in the electric circuit occurring when one of said temperature differences as compared to a respective trigger value indicates that fluid has been demanded from the pipe.    
   
   
       3 . The device of  claim 2  wherein a plurality of temperature differences are measured within the preselected time interval.  
   
   
       4 . The device of  claim 3  wherein the processor updates at least one trigger value based on a comparison of the trigger value to historical temperature differences inferred from data saved in a memory device that is in signal communication with the processor.  
   
   
       5 . The device of  claim 4  wherein the preselected time interval is in the range of 0.1 to 15 seconds.  
   
   
       6 . The device of  claim 5  wherein the trigger values lie in a range of about 0.001 to 100 degrees Fahrenheit.  
   
   
       7 . The device of  claim 6  wherein the sensor is a non-contact temperature sensor.  
   
   
       8 . The device of  claim 6  wherein the sensor is an infrared temperature sensor.  
   
   
       9 . The device of  claim 3  wherein: 
 the first pipe is a hot water pipe in a hot water circuit;    the hot water circuit is in fluid communication with a pump and a valve;    the sensor senses the temperature at a location on the outer surface of the first pipe; and,    the valve is operative to demand hot water from the hot water circuit and the electric power circuit is operative to actuate the pump in response to the hot water demand.    
   
   
       10 . The device of  claim 9  wherein the sensor is an infrared temperature sensor.  
   
   
       11 . The device of  claim 10  having a means to deactivate the pump.  
   
   
       12 . The device of  claim 11  wherein: 
 the processor saves in a memory device an indication of at least a first time on a first day when hot water is demanded from the hot water circuit; and,    the processor actuates the pump on a second day subsequent to the first day at a second time which differs from said first time by a first predetermined time difference.    
   
   
       13 . The device of  claim 12  wherein: 
 on a day subsequent to the first day the processor makes the first time indication previously saved in the memory device ineffective to actuate the pump when hot water is not demanded between a fourth time and a fifth time, said fourth and fifth times differing from said first time by respective second and third predetermined time differences.    
   
   
       14 . The device of  claim 13  wherein the pump is a recirculation pump.  
   
   
       15 . The device of  claim 3  wherein: 
 the first pipe supplies cold water to a water heater;    a second pipe is a hot water pipe in a hot water circuit;    the hot water circuit is in fluid communication with the water heater, a pump and a valve;    the sensor senses the temperature at a location on the outer surface of the first pipe, said location being proximate to said hot water heater; and,    the valve is operative to demand hot water from the hot water circuit and the electric circuit is operative to actuate the pump in response to the hot water demand.    
   
   
       16 . The device of  claim 15  wherein the sensor is an infrared temperature sensor.  
   
   
       17 . The device of  claim 16  having a means to deactivate the pump.  
   
   
       18 . The device of  claim 17  wherein: 
 the processor saves in a memory device an indication of at least a first time on a first day when hot water is demanded from the hot water circuit; and,    the processor actuates the pump on a second day subsequent to the first day at a second time which differs from said first time by a first predetermined time difference.    
   
   
       19 . The device of  claim 18  wherein: 
 on a day subsequent to the first day the processor makes the first time indication previously saved in the memory device ineffective to actuate the pump when hot water is not demanded between a fourth time and a fifth time, said fourth and fifth times differing from said first time by respective second and third predetermined time differences.    
   
   
       20 . The device of  claim 19  wherein the pump is a recirculation pump.  
   
   
       21 . A fluid demand detection device comprising: 
 a pipe for transporting a fluid;    a sensor for sensing a temperature that varies with the temperature of the fluid;    a processor in signal communication with the temperature sensor and a time base;    the processor for making a plurality of temperature measurements corresponding to different times and for calculating at least one temperature difference between a first temperature measured at a first time and one or more second temperatures measured at one or more respective second times subsequent to said first time;    each of the times bounded by a single preselected time interval; and,    the processor for causing an electrical current to flow in an electric circuit when one of said temperature differences as compared to a respective trigger value indicates that fluid has been demanded from the pipe.    
   
   
       22 . The device of  claim 21  wherein: 
 the pipe is in fluid communication with a hot fluid source; and,    the sensor is an infrared temperature sensor located adjacent to the pipe and proximate to the hot fluid source.    
   
   
       23 . A method of detecting hot water demand comprising the steps of: 
 transporting hot water in a first pipe in fluid communication with a potable hot water source and a hot water valve;    measuring a plurality of temperatures corresponding to different times with an infrared temperature sensor in signal communication with a processor said temperatures being measured at a location on an outer surface of a second pipe transporting cold water to the hot water source;    varying the temperature of the location on the outer surface of the second pipe by opening and closing the valve;    calculating a time rate of temperature change; and,    signaling a recirculating pump to transport water from the first pipe to the hot water source when the time rate of temperature change exceeds a preselected trigger value.