Skip Gundlach wrote:

So, if I understand vented loops properly, suction gets air, rather than
water, thus preventing siphoning. So, how do you suck in the supply water
if the supply line is vented???

Skip, have you ever bothered to the read the manual for your toilet? It
includes drawings showing the locations for both discharge and intake
vented loops.

If you don't have a manual for it, download and print one from the mfr's
website. Not only do the manuals illustrate where to put the loops, they
also include exploded diagragms of the pumps and most have
trouble-shooting guides.

That said, there are some very high end manual toilets--W-C Skipper,
Groco EB and Model K--that don't have the short piece of hose connecting
the pump to the bowl...the only place TO put a vented loop in the intake
is in the line between the thru-hull and the pump. However, the design
of these toilets also makes a vented loop in the intake unncessary.

There's no way to put one between the pump and the bowl on most electric
macerating toilets either...it has to go between the thru-hull and the
pump. Instead of just an air valve in the top of the loop, it's
necessary to intall an electric solenoid valve that's wired to the flush
button.

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/store/custo...0&cat=6&page=1
http://shop.sailboatowners.com/books...ku=90&cat=1304

That said, there are some very high end manual toilets--W-C Skipper, Groco
EB and Model K--that don't have the short piece of hose connecting the
pump to the bowl...the only place TO put a vented loop in the intake is in
the line between the thru-hull and the pump. However, the design of these
toilets also makes a vented loop in the intake unncessary.

Thanks Peggy, that answers the question I was going to ask. I have one of
those manual types, I can't remember which right now and I'm not at the boat
to look, but it has a spring loaded pedal that you step on to flush. When I
purchased the boat, the surveyor wrote it up as needing a vented loop and
the insurance company dutifully required it, I could see no way of
installing one so I replied back that it was not possible or needed with my
head. Also the PO had conveniently installed second shutoff right alongside
of the head that can easily be reached even when sitting on it. I use this
religiously. The insurance company (BoatUS) never replied back so I suppose
they are good with it.

John