what I did
Basically, I took out the old unit (Sea Ward--Sea something, I can't remember)and bolted in the new unit (WC Head Mate)and all the existing fittings and hoses matched up with the old unit as per the instructions--discharge goes to tank, intake comes form sea cock. There is an existing vented loop but it is attached to the holding tank manual discharge pump which I have never used and plan to remove at some point. I also plan to replace hoses and install a vented loop as per your reccomendation, but I ran out of time and I didn't want to go farther until I figured out what the problem is. BTW, the head works fine in the "dry" mode.
