I have a large cistern in my back garden that collects the rainwater run-off from the house roof and yard. I mainly want to use the water for watering plants but I'd also like the cistern to syphon to a pond in a lower part of the garden - and to self-syphon when the cistern becomes full. I already have the pipe-runs in place to be able to do this but no way of controlling the flows.
I'm keen to experiment to find-out the different options I can set up with a bit of design effort, one or two gate valves and a one-way valve to release air from the syphon. My pipework is 40mm plastic (type used with solvent-weld).
Installation is outside. Very modest pressure - 1 metre head.
I'd be grateful for any info on the availability the sorts of valve that would be suitable. I imagine there are fish-farms, etc that use this kind of stuff.
Also - is it possible to use an air-admittance valve (say the kind used on waste traps) back to front, so as to make an air-release valve? I'm pretty sure this is what I need to start my self-syphon. I have experimented using by hand as an air release-valve and it seems to work. I can see how I might have done it all a lot better if I was starting at the beginning but there are certain critical levels that are impossible to change now.
Thanks in advance
Dave