Roof siphon drain

Apparatus for siphoning liquid which accumulates in a ponding area located at a first level to a second level lower than said first level in a drain means comprising:

• a first liquid conduit having a receiving end and a discharge end, said receiving end of said first liquid conduit terminating at a valve unit and said discharge end terminating in said drain at said second level located a selected distance below said receiving end;
• a second liquid conduit having an upper end terminating at a receiving tank and a lower end terminating at said valve unit;
• a reservoir for accumulating a selected volume of liquid at least sufficient to completely fill said first liquid conduit, said reservoir being located at a level above said discharge end of said first liquid conduit, and being pivotally mounted and balanced such that when said selected volume of liquid has accumulated, said reservoir will pivot and dump said selected volume of liquid;
• said receiving tank located below said reservoir, and said receiving tank being connected to said upper end of said second liquid conduit with a liquid tight connection so that said selected volume of liquid will flow through said second liquid conduit;
• and
• said valve unit located in said accumulated liquid in said ponding area and having a liquid tight connection with said receiving and of said first liquid conduit and said lower end of said second liquid conduit, said valve unit having a first operating position for providing a first liquid path between said accumulated liquid in said ponding area to said receiving end of said first liquid conduit, and said valve unit being suitable for switching to a second operating position when said selected volume of liquid is dumped from said reservoir to said receiving tank such that said first liquid path is closed and a second liquid path is provided between said lower end of said second liquid conduit and said receiving end of said first liquid conduit such that said dumped liquid flowing through said second liquid conduit completely fills said first liquid conduit to initiate a siphoning action between said receiving end and said discharge end of said first liquid conduit, said valve unit switching back to said first operating position after said siphoning action is initiated to move liquid accumulated in said ponding area through said first liquid conduit to said drain means.