In the 1950’s an engineer from North Carolina by the name of Harry E Thompson invented a simple method of collecting solar heat without using copper flow tubes bonded to a metallic absorber plate. Conventional collectors use copper flow tubes to harvest the sun’s trapped heat from a blackened absorber plate. Commercial parallel flow tubes are soldered to a copper absorber plate and serpentine flow tubes may be pressure bonded to an aluminum absorber plate. Although the serpentine collector uses less Copper than the parallel flow system they both rely on Copper to isolate collector fluid from the glazing.Harry Thompson felt that flow tubes and copper absorber plates were an unnecessary expense. Instead of using flow tubes Harry decided to pump water from a storage tank to the ridge of a roof and allow it to dribble down across a corrugated aluminum absorber plate. Thus heat transfer occurred directly from the absorber plate into the water.
At the bottom of the corrugated aluminum roof a gutter was a gutter was placed to catch the heated water and channel it back into a huge heat storage tank in the basement. The tank was buried in a pit of stones and a thermostat on the first floor was used to turn on a fan that forced cold house air across the heated stones. The heated air from the stones in then entered the living area through grates in the first floor.
This method of solar heating a house is still used along the Canadian border, but concerns about heat loss through the glazing and high installation costs prevented wide spread acceptance of the Trickle Down Solar Roof. I felt Thompson’s basic idea was good but I also felt it needed work so I decided to develop a low-cost, DIY, modular collector that could be easily installed and maintained. I call this Modified Trickle Down solar heating or MTD. Thanks to the inspiration of Harry E. Thompson and the research efforts of Richard Heiliger the dream of a low-cost, practical, DIY solar application eventually became a reality. The MTD experiments listed in this blog led to the development of MTD starter kits that are now shipped to locations all over the world.
http://www.jc-solarhomes.com/MTD/MTD_solar_heating.htm
