[Public-List] Head questions

[Jim Davis]

This is just my opinion

"1. Is there any reason to put the vented loop on the intake? I have never had 
this before, but I have seen it on a few installations."
Yes   If the intake is normally left open.  The rim of the bowl is about the same height as the waterline.  This can redefine "Down by the Head".  On Isa Lei we keep the intake closed, except for flushing.

"2. I plan on having the vented loop between the head and the holding tank. Have 
people had problems with waste siphoning from the tank back into the head. When 
the head was connected to the through hull, this made more sense."
I see no need for a loop here as long as you go directly to the tank.  The hose to the tank should go to the top of the tank so it is pumping into air, therefore no need for the loop.  About the only time a head will back fill is when the joker valve needs replacing and raising the hose high enough to put a vent in will increase the back pressure on the valve.
http://www.boatus.com/boattech/casey/04.htm



Jim Davis
S/V Isa Lei
CT 35

Although a soldier by profession, I have never felt any sort of fondness for war, and I have never advocated it, except as a means of peace.
Ulysses S. Grant