Originally Posted by Maine Sail
Just be sure your "exit" hose does not have any dips in it that can collect and hold water. With a bad impeller even a small "trap" can cause a siphon.
For engine vacuum breakers I prefer the ones made by the Scot Pump Co. as I find they are far more trouble free than a duck bill....
You can buy just the vacuum breaker:
Or the whole thing:
I tend to just make custom ones:
This was Ericson's idea for a siphon break and it sprayed salt water all over the engine when the brazed copper tube failed. It was also mounted under the cockpit:
A few dollars and 30 minutes later a new one that is significantly more robust replaced it.
In the last (bottom pic) where does the vent hose go?