Pump drained solar water heating system

Abstract

A pump drained solar water heating system, includes a solar collector; a reversible pump; a reservoir for storing heat transfer fluid; an insulated water storage tank for storing the potable water; piping for fluidically connecting the pump to the solar collector, the heat transfer fluid reservoir; and a heat exchanger; and a controller for operating the pump to transmit fluid in a forward flow or reverse flow direction.

1 . A solar water heating system, comprising:
 a solar collector;   a reversible pump;   a reservoir for storing heat transfer fluid;   a heat exchanger for transferring heat from the heat transfer fluid to potable water;   an insulated water storage tank storing said potable water;   piping for connecting said pump, said collector, said heat transfer fluid reservoir, and said heat exchanger in fluid communication; and a   controller for operating the pump to transmit fluid in a forward flow direction for heating the water and in a reverse flow direction to drain the fluid from the collector to the reservoir.   
     
     
         2 . The solar water heating system of  claim 1 , further comprising a sensor connected to said collector for determining temperature of the fluid in said collector. 
     
     
         3 . The solar water heating system of  claim 2 , further comprising a second sensor connected to said water storage tank for sensing temperature of the water in said storage tank. 
     
     
         4 . The solar water heating system of  claim 2 , wherein said controller is connected to said first sensor. 
     
     
         5 . The solar water heating system of  claim 3 , wherein said controller is connected to said second sensor. 
     
     
         6 . The solar water heating system of  claim 5 , wherein when said controller detects a temperature differential, in the range of 9° F. to 18° F. between the temperature sensed by said first and second sensors, said controller activates said pump in said forward direction. 
     
     
         7 . The solar water heating system of  claim 6 , wherein when said controller detects a temperature differential between said first and second sensors which is less than 9° F., said controller deactivates said pump. 
     
     
         8 . The solar water heating system of  claim 5 , wherein said second sensor is operative to detect a temperature greater than a maximum reference water temperature and said first sensor is operative to detect a temperature greater than a maximum reference collector fluid temperature and said controller is operative in response to said detection by said first sensor or said second sensor to activate a pump flow reversal to evacuate the heat transfer fluid from the system to the reservoir. 
     
     
         9 . The solar water heating system of  claim 4 , wherein said first sensor detects a minimum set level which activates a pump flow reversal which evacuates the heat transfer fluid from the system to the reservoir. 
     
     
         10 . The solar water heating system of  claim 1 , further comprising a reserve power supply for energizing the system and wherein said controller is operative in response to a loss of externally supplied power to activate said reserve power supply and to operate the pump in a reverse direction to evacuate the heat transfer fluid from the system to the reservoir. 
     
     
         11 . The solar water heating system of  claim 1 , wherein said heat transfer fluid storage reservoir comprises a baffle to control fluid drainage into said reservoir. 
     
     
         12 . The solar water heating system of  claim 1 , further comprising a pressure-vacuum valve adjacent said heat transfer fluid storage reservoir.