Re: the "vent" on a vented loop
Maine Sail, yes it does look much like that white "siphon break" part on the top, but the loop is a continuous piece of stainless, not two elbows and a T. The Forespar valves ebs001 found are exactly what I need, but unfortunately won't fit the loop, so I bought a new Forespar vented loop complete with vent. I'm not going to bother to vent overboard with the new install, seeing as someone pointed out it only sucks air in, so no sewage smell should escape (the holding tank will still vent overboard, of course). Thanks for your help.
1979 Gulfstar 37 Laissez Faire