The always dripping anit-siphon value??

[Paul L]

I have an anti-siphon value on my Volvo exhaust. It breaks the salt water input to the exhaust mixer prior to the muffler. The value is located aprox 5 inches above the water line. At this point the little check value at the top is removed and open. It drains through a small hose that drains into a sump that is below the waterline. If I leave the salt water intake seacock open, then this anti-siphon hose will very slowly drip forever (weeks). If I shut the intake value, then the dripping will stop. This doesn't make sense to me. Why the continual drip when the engine is not running?

Paul L

[cal40john]

The end of that tube is supposed to go up, not down. Your siphon break is actually a siphon.

John

[Paul L]

Originally Posted by cal40john

The end of that tube is supposed to go up, not down. Your siphon break is actually a siphon.
John

I always wondered about that when I got the boat. It just didn't seem like the plumbing made sense. I did try moving the tube and holding it up high, but not sure I waited long enough., I'll try that again.

Paul L

[GordMay]

There’s some diagrams of Exhaust System layouts at:

Typical Exhaust Diagrams
http://www.cruisersforum.com/gallery...=500&userid=79

Exhaust System Fundamentals ~ by Dave Gerr
http://www.cruisersforum.com/gallery...=500&userid=79

Yanmar Exhaust Diagram
http://www.cruisersforum.com/gallery...=500&userid=79

TRANSVERSE EXHAUST SYSTEM
http://www.cruisersforum.com/gallery...=500&userid=79

[Paul L]

My setup is similar to fig 1 of the 2nd link you posted. The engine is mid-ship. To get the anti-siphon significantly above the waterline, they routed the in-out line for it down low in the bilge then up into a locker. This ended up placing the anti-siphon at about 5 inches above the water line. Less than recommended, but should work. Then the value tip of the anti-siphon has a small tube that runs back to the bilge so no water drains into the locker. This tube is below the water line. So I guess the net affect is that the anti-siphon value acts as if it were also below the water line.

Paul L