E32-3 Water Tank Vents

[C Masone]

We ran out of water in our starboard tank, my son said that it was full when he went to fill it, I knew that was wrong and that it was probably a pluged vent. I opened the accsess panel and removed the vent and blew through it and sure enough there was water trapped in some low point that I blew out into the vent pipe that leads to the sink in the head.

I assume that the vent line runs through the bilge which is totally absurd anybody would know that it will fill and form a blockage.

Has anyone run a new vent that does not form a trap? How did you do it?

 

[Gary Schroeder]

water alone won't block the vent line

The vent lets air escape out of the top of the tanks so that water can enter, sort of like bleeding a diesel fuel system. You might have had a blockage that came out when you blew through the line.

As long as the entire vent line and its outlet are below the water fill, any water in the line will be displaced by water added higher up in the system - like at the fill. Water in the tank weighs a lot more than the air on the other side of your low spot, so it will flow right on through.

The owners manual cautions against adding water too fast because it can only go in as fast as the air can escape from the vent.

 

[footrope]

Hi,

I had a similar problem with a midship tank that "ran out of water" while nearly full. The vent ran 15 feet aft to the galley sink and was only about a foot above the top of the tank. It had low spots in it between bulkheads. Easy to contaminate with water and water is plenty heavy to block air. I doubt you have anything but water in the vent where it is low. Below is a link that might give you some ideas about how to deal with it.

http://www.ericsonyachts.org/infoex...09-E38-Settee-(20-gal.)-fresh-water-tank-vent

Re-reading that 7 years later reminded me that the factory vent had a modification, and that was probably the reason why it underperformed standard factory installations. Since I could not restore the factory run to the galley, I decided to re-plumb the settee tank vent to the bow tank fill line (yes, the fill line) with a vented loop in between. The bow tank already vents very reliably into the head sink, so I am using the bow tank vent for both tanks now. This modification has worked great since I installed it. I don't even think about it anymore. I can fill the settee tank without worrying about it. I do keep an eye on the bow tank fill so that it doesn't run very long after filling. Also, be sure the sink drains are open while you fill if you have a vent going to a sink.

Good luck with your project.

 

[C Masone]

Thanks Footrope

This will be very helpful. I will have to decide how I want to do this.