Control for a tankless water heater used with a solar water heating system

Abstract

A tankless water heating auxiliary system for a solar water heating system, includes a solar collector; a tankless water heater auxiliary system; an insulated water storage tank storing the potable water; a heat exchange system for heating stored water; and piping for connecting the collector, the storage tank and the heat exchanger in fluid communication. A first sensor is connected to and located adjacent the storage tank for sensing the temperature of the stored water at an outlet of the tank. A method for controlling initiation of heating in a tankless water heater auxiliary system, includes monitoring operation of a tankless water heater; measuring water flow using a water flow sensor to determine if water flow rate exceeds a use determined flow rate; implementing a control time delay into the tankless water heater to purge water from the heater and sense the inlet water supply temperature; measuring the water temperature using a heat exchanger outgoing thermistor; comparing the temperature measured by the thermistor to a predetermined temperature; and initiating a combustion sequence if the temperature measured by the outgoing themistor is less than the predetermined temperature.

What is claimed is: 
     
         1 . A tankless water heating auxiliary system for a solar water heating system, comprising:
 a solar collector;   a tankless water heater auxiliary system;   an insulated water storage tank storing potable water;   a heat exchange system for heating stored water;   piping for connecting said collector, said storage tank and said heat exchanger in fluid communication; and a   first sensor connected to and located adjacent said storage tank for sensing the temperature of the stored water at an outlet of said tank.   
     
     
         2 . The tankless water heating auxiliary system of  claim 1 , further comprising a controller connected to said first sensor. 
     
     
         3 . The tankless water heating auxiliary system of  claim 2 , wherein when said first sensor detects whether the water temperature in said storage tank is greater than or less than 120° F. 
     
     
         4 . The tankless water heating auxiliary system of  claim 3 , wherein said first sensor is placed on a top surface of said tank. 
     
     
         5 . The tankless water heating auxiliary system of  claim 3 , wherein said first sensor is placed inside of said tank. 
     
     
         6 . The tankless water heating auxiliary system of  claim 4 , wherein said first sensor is connected to said tankless heater via wire. 
     
     
         7 . The tankless water heating auxiliary system of  claim 6 , wherein said first sensor is operative to detect a temperature greater than a predetermined maximum reference water temperature. 
     
     
         8 . The tankless water heating auxiliary system of  claim 7 , wherein when said first sensor detects a temperature below a predetermined maximum reference temperature, said burner is activated. 
     
     
         9 . The tankless water heating auxiliary system of  claim 7 , wherein when first sensor detects a temperature above 120° F., said burner is not activated. 
     
     
         10 . A method for controlling initiation of heating in a tankless water heater auxiliary system, comprising:
 monitoring operation of a tankless water heater;   measuring water flow using a water flow sensor to determine if water flow rate exceeds a use determined flow rate;   implementing a control time delay into the tankless water heater to purge water from the heater and sense the inlet water supply temperature;   measuring the water temperature using a heat exchanger outgoing thermistor;   comparing the temperature measured by said thermistor to a predetermined temperature; and   initiating a combustion sequence if the temperature measured by said outgoing themistor is less than said predetermined temperature.