Vented loop thoughts?

[fixin-to-cruise]

I have some 1990 vintage Hatteras with vented loops in some of the toilet hoses. They are made of bronze elbows and tee fittings with a "Scott Marine" white plastic vent with a spring inside. Over the years they have leaked some nasty stuff and caused some corrosion on the aluminum rubber insulated clamps, etc. I've restored everything to good condition (including the vents) but I am considering replacing the vented loops with more reliable ones.

I bought a couple of Groco HVL-1000 vented loops for $75 each but the instructions say "it is essential, particularly when used in waste systems, that the cap be removed periodically and the inside of the loop inspected for obstructions....the result is backfilling of the toilet...". Seems like the failure mode of the old ones was a leak and the Groco's could sink the boat!

Anybody with experience with different vented loops? I'm looking for one that's reliable!

[Fanfare]

The loops are intended to go up above the waterline and down again so water can't backflow into the boat. The vent is designed to open when there is a vacuum and let air into the loop to prevent back siphoning. They close when there is pressure, as in when you flush. The vents need occasional cleaning due to the corrosive material they have going through. If there were no vent, and the discharge was below water level, perhaps due to overloading, then the water from outside can run back and sink you. If they are cleaned regularly they seem to be fairly reliable.


Some years ago I had the forward bilge pump back siphon, nearly ruining the generator and batteries. It washed off all the labels on the bottles of wine in our forward compartment. We could tell red from white, but could no longer tell the vintner until we opened the bottle and could read the writing on the cork. I wouldn't want this tragedy to happen to anyone else. Have vented loops and maintain them!

[fixin-to-cruise]

What make & model vented loop worked the best for you? How often did you need to service them? I'm leaving them in where they belong, but looking for a recommendation on more trouble-free ones to replace mine, if there is a better one then the "Scot Marine Vacuum Breaker" setup from Hatteras.

I'd be happy to help you identify the wine!