Mailport: February 2014
Thank you for your review of the H2Out AVD diesel tank vent filters, and especially the tips on installation best practices (PS, January 2014). You’ve confirmed for me that I made the right move, and more importantly, that I actually installed the unit correctly on my boat.
Sailboats have a bit of advantage over their power cousins in that we have more high spots that can be used creatively. In my installation, the diesel vent line (fuel-grade hose) loops high inside at the transom and back down to the through-hull. Through the use of a check valve, air flows out, but intake air comes in through the AVD, which is attached to the underside of the deck; no additional support needed. The unit is readily available for inspection or replacement through the transom locker, and it is not in the way of any equipment that needs to go in or out. Love the H2Out AVD2 vent filter; kudos to Pindell Engineering.
Content, Rhodes (Chesapeake) 32
Herring Bay, Md.
In this installation—which is suitable for diesel but not gasoline systems—the fuel tank breaths out directly overboard and breaths in through the silica-gel vent filter. The tee in the picture contains two check valves, which work to prevent contamination of the media during tank overfills. Unique to H2Out-maker Pindel Engineering, this vent installation method is not directly addressed by any code. The U.S. Coast Guard does not regulate diesel fuel systems, and the American Boat and Yacht Council (ABYC) is mute on this detail.
For gasoline systems, the regulations are quite clear: Vents must discharge outside the hull in a location where vapors cannot easily re-enter the cabin, with no exception for valve-regulated systems. The correct practice is to protect against sea water by a P-trap in the through-hull or a high loop. Practical Sailor discussed installation in the January and February 2013 issues.
Check valves in raw-water cooled exhaust installations should be monitored. The diesel-vent assembly should not rely on a check valve for preventing fumes from getting inside the boat.
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