Hi again,

I've relocated the anti-siphon vent in our raw water circuit.

Originally it was a typical installation with one of those plastic
vented valves at the top of a U.

There was evidence of this installation spraying water on that side of
the engine, causing corrosion on the starter and starter connections.

For this reason, Nigel Calder recommends this anti-sipon be plumbed to
the outside of the boat (above the waterline at all angles of heel), or
as he did on his boat, into the cockpit.

I plumbed it into the cockpit on a vertical wall, about two feet above
the cockpit sole.

When we started the motor today, I wasn't that surprised to see that
water was making its way up the vent and dripping into the cockpit.
We'd rather not have 200 degree water in the cockpit, so we'll have to
remedy this.

Is there any reason why I can't just plumb a one way check valve into
the line, to stop water from exiting, but to let air enter?

Or, do I need some kind of pressure valve?

Thanks for the help,

Mike.