Mike, your dam crossover pipe functions the same as if it were a straight drain pipe through your dam.
If you wanted your normal pool level at X freeboard, that should be where the inner bottom of your crossover pipe should be. As water rises above normal, your pipe drains normally. If you set the inlet height of your VENT pipe at say, 5 inches above normal level, you would still not get a siphon started until the pool was above the TOP of your crossover pipe and has evacuated enough air in the system to start a siphon (because your vent inlet is under water and "sealed") The siphon would theoretically break when the pool was back to 5" above normal pool and the pipe becomes a normal drain again..in reality, due to whirlpooling, a 5" rise set on the vent will break at 7-9" above normal pool
Last edited by Rainman; 06/10/13 07:10 PM.
