Solar water heater

A solar water heater, comprising in combination:

• a water containing space;
• a lens positioned between said water containing space and the sun;
• an airspace between said lens and said water containing space;
• a heat control valve between said air space and air outside of said air space, said heat control valve set to open said air space to air outside of said air space when a set temperature is exceeded by the air within said air space;
• wherein said heat control valve spans multiple elevations when open, such that natural convection of air through said valve is enhanced relative to a heat control valve of similar size having a single elevation;
• and
• wherein said lens is slanted to include a high end and a low end, said valve selectively closing a gap extending at least partially between said low end of said lens and said high end of said lens.

A solar water heater comprising in combination:

• a water containing space;
• a lens positioned between said water containing space and the sun;
• said lens having at least one void therein, said void isolated from adjacent spaces outside of said lens, said void having an at least partial vacuum condition relative to the adjacent spaces, such that a rate of conduction heat transfer through said lens is reduced relative to a rate without said vacuum condition;
• wherein said lens has a non-planar top surface;
• wherein said lens has an undulating top plate;
• and
• wherein said lens includes an undulating bottom plate, said undulating bottom plate and said undulating top plate touching each other at abutments where undulations in said undulating top plate and undulations in said bottom plate come together, and wherein said lens includes a plurality of said voids between said undulating top plate and said undulating bottom plate at spaces between said abutments, said voids having an at least partial vacuum condition relative to air above said undulating top plate.

A solar water heater, comprising in combination:

• a water containing space;
• a lens positioned between said water containing space and the sun;
• an air space between said lens and said water containing space;
• a heat control valve between said air space and air outside of said air space, said heat control valve set to open said air space to air outside of said air space when a set temperature is exceeded by the air within said air space;
• wherein said air space is configured as an air trap which is substantially enclosed except when said heat control valve is open;
• wherein said heat control valve spans multiple elevations when open, such that natural convection of air through said valve is enhanced relative to a heat control valve of similar size having a single elevation;
• and
• wherein said heat control valve passes through said lens, such that air exchange occurs between air in said air space and air above said lens when said valve is open.

A solar water heater comprising in combination:

• a water containing space;
• a lens positioned between said water containing space and the sun;
• said lens having at least one void therein, said void isolated from adjacent spaces outside of said lens, said void having an at least partial vacuum condition relative to the adjacent spaces, such that a rate of conduction heat transfer through said lens is reduced relative to a rate without said vacuum condition;
• wherein an enclosable air space is located between said lens and said water containing space;
• and
• wherein said enclosable air space includes a gap between said enclosable air space and air surrounding the solar water heater, said gap having a valve therein, said valve selectively opening and closing said enclosable air space relative to air surrounding the solar water heater;
• wherein said valve includes a closed position closing said gap and an open position exposing said gap, said valve biased toward said closed position;
• wherein said valve includes a cover, said valve including a heat expansion element adjacent said cover, said heat expansion element configured to expand against said cover and lift said cover to move said valve from said closed position to said open position when said heat expansion element experiences a threshold temperature, such that said valve is moved from said closed position to said open position when said heater transfer element exceeds a preselected maximum temperature;
• wherein said heat expansion element is located within said air space in a manner keeping a temperature of said heat expansion element and air within said air space similar to each other;
• and
• wherein said lens has a non-planar top surface, said lens divided into at least two panels with said gap between said air space and air surrounding said solar water heater, said gap located between said at least two panels, said cover of said valve located spanning said gap.