Heppy, after I first saw DC70's system I had the same thoughts regarding a completely closed system. I also have the same thoughts as Hogfan, regarding whether or not the chamber needs to be opened to the atmosphere to allow the displacement of air with water. Perhaps a sufficient volume of air in a completely close system would overcome vapor lock, and allow it to work, I dunno.

I suppose some experimentation could be done on a smaller scale using small piping or tubing. If a full size system were built and it failed, at least you could correct it by way of adding a vent tube as Hogfan suggested.

Also, perhaps I'm missing something, but I don't understand your idea of drilling the holes in the smaller vent pipe. It seems to me that the highest hole in the vent pipe is the only one of importance, therefore that is where the end of the pipe should be, as with a normal automatic siphon system.

Edit: Doh! I just saw your above post, where you explained that the perforated vent pipe acts as a trash guard. That's a good idea!

Last edited by gully washer; 08/25/18 12:41 PM.