Overtemperature protection system for a solar water heating system

Abstract

The invention provides a solar hot water heating system including one or more solar energy absorbers ( 102 ) having at least a first fluid circulation path wherein, an over temperature path ( 119 ) is provided, the over temperature path including a pressure vessel ( 120 ) which is normally closed to atmosphere, the over temperature path being connected to the first fluid circulation path ( 108 ) so that, in the event that fluid in the solar energy absorber vaporizes, the fluid is forced out of the solar energy absorber and into the pressure vessel. The present invention also provides a temperature sensitive valve leaving a flow path and a valve member operated by a thermal element having thermal expansion characteristic the valve including a support member against which the thermal element expands to force the valve element to close the flow path.

1 . A solar water heating system including one or more solar energy absorbers having at least a first fluid circulation path, wherein an overtemperature path is provided, the overtemperature path including a pressure vessel which is normally closed to atmosphere, the overtemperature path being connected to the first fluid circulation path so that, in the event that fluid in the solar energy absorber vaporizes, the fluid is forced out of the solar energy absorber and into the pressure vessel. 
     
     
         2 . A solar water heating system including one or more solar energy absorbers and a heat exchanger connected in a fluid circulation path, wherein:
 an overtemperature path is provided;   the overtemperature path including a pressure vessel which is normally closed to atmosphere;   the overtemperature path being connected to the fluid circulation path so that, when heat transfer fluid in the solar energy absorber vaporizes, the heat transfer fluid is forced out of the solar energy absorber and into the pressure vessel.   
     
     
         3 . A solar water heating system as claimed in  claim 2 , wherein the fluid circulation path includes a valve arranged to facilitate the evacuation of heat transfer fluid from the solar energy absorber under the pressure from evaporated heat transfer fluid in the solar collector. 
     
     
         4 . A solar water heating system as claimed in  claim 3 , wherein the valve can be one of:
 a one way valve;   a pressure actuated valve;   a temperature actuated valve;   a controllable valve; or   a combination thereof.   
     
     
         5 . A solar water heating system as claimed in  claim 1 , wherein the fluid entering the pressure vessel increases the pressure in the pressure vessel, so that, when the temperature of the fluid vapour in the solar collector falls below the vaporization temperature, the pressure in the pressure vessel forces the fluid back into the fluid circulation path and the solar energy collector is replenished with fluid. 
     
     
         6 . A solar water heating system as claimed in  claim 1 , wherein the overtemperature path include a pressure relief valve. 
     
     
         7 . A solar water heating system as claimed in  claim 1 , wherein the pressure vessel has a substantially tubular shape. 
     
     
         8 . A solar water heating system as claimed in  claim 1 , wherein the pressure vessel is inclined at an angle to the horizontal. 
     
     
         9 . A solar water heating system as claimed in  claim 1 , wherein the pressure vessel includes a riser. 
     
     
         10 . A solar water heating system as claimed in  claim 10 , wherein the pressure vessel tube is formed from a pipe suitable for use as a flue in a centrally flued hot water tank. 
     
     
         11 . A solar water heating system as claimed in  claim 1 , wherein the overtemperature path is connected at the to of the fluid circulation path. 
     
     
         12 . A solar water heating system as claimed in  claim 3 , wherein the fluid entering the pressure vessel increases the pressure in the pressure vessel, so that, when the temperature of the fluid vapor in the solar collector falls below the vaporization temperature, the pressure in the pressure vessel forces the fluid back into the fluid circulation path and the solar energy collector is replenished with fluid. 
     
     
         13 . A solar water heating system as claimed in  claim 3 , wherein the overtemperature path include a pressure relief valve. 
     
     
         14 . A solar water heating system as claimed in  claim 3 , wherein the pressure vessel has a substantially tubular shape. 
     
     
         15 . A solar water heating system as claimed in claim  3 , wherein the pressure vessel is inclined at an angle to the horizontal. 
     
     
         16 . A solar water heating system as claimed in  claim 3 , wherein the pressure vessel includes a riser. 
     
     
         17 . A solar water heating system as claimed in  claim 16 , wherein the pressure vessel tube is formed from a pipe suitable for use as a flue in a centrally flued hot water tank. 
     
     
         18 . A solar water heating system as claimed in  claim 3 , wherein the overtemperature path is connected at the top of the fluid circulation path. 
     
     
         19 . A temperature sensitive valve having a flow path and a valve member operated by a thermal element having thermal expansion characteristic, the valve including a support member against which the thermal element expands to force the valve element to close the flow path. 
     
     
         20 . A temperature sensitive valve as claimed in  claim 19 , wherein the valve includes a hollow body containing wax and a piston. 
     
     
         21 . A temperature sensitive valve as claimed in  claim 20 , wherein the piston is spring biased to tend to compress the wax.