Skip Gundlach wrote:
Because I haven't yet obtained (later today) the intake hoses, I just
filled the bowl from the shower hose. Moving the selector to "dry" I
pumped it out.

Everything went just fine. Until, after I quit more than a dozen
strokes after the noise indicated the last of the water had been
removed from the pipe under the stool (the flapper opening on intake,
then closing on pump), I heard the water cascade back down into the
area of the joker.

Based on several threads, both recent and long ago, I had *thought*
(after an annoyingly high number of confirmation questions in a
long-ago thread, because my [limited] physics understanding refused to
believe it) that you could dry pump all the liquid out of the standing
part of the vented loop.

Yes...you should be able to, provided the toilet is working anywhere
near spec and the lift doesn't exceed about 4' (6' horizontal). So one
or more of 3 reasons isn't letting you do it.

1. Your vented loop is higher than the toilet can lift it.

2. The lift is marginal, a dozen pumps aren't enough.

3. You tried to save money by buying a used PH II on eBay that's turned
out to be so old and worn--or the inside of the pump cylinder is so
scratched and scored by grit and salt--that new seals and o-rings can't
bring it back to specs.

Evidently I'm doing something wrong, because it doesn't. Trying it
"wet" (not wet because I don't have the lines, and I'm not in the water
if I had) didn't make any difference.

It wouldn't...the only thing that "wet" does is allow flush water
IN...it has nothing to do with discharge.

Pumping wildlly (perhaps 2-300
strokes per minute rate) didn't change matters.

That actually defeated what you were trying to accomplish 'cuz flailing
only "aerates" the discharge. Slow deliberate pumping is FAR more
efficient.

I still assume I'll be able to push everything out of the pipe below,
as, once the fall has occurred, and the anti-syphon has let in the air
to take up the space, the next stroke should pressurize it, leading to
the air bubble going all the way to the through hull.

What air bubble??? The air valve in the vented loop only brings air
into a line through which liquid is being PULLED...it doesn't do a thing
in a line through which anything is being pushed. So there is no "air
bubble" in the dishcarge line. The vented loop is only there to prevent
the SEA from starting a siphon back into your toilet...it doesn't have
anything whatever to do with flushing a toilet.

I'm beginning to wonder if ANYone knows how a vented loop works!

Our marker for
success will be to have the t/h bubble (I'm sure there is a quantified
number of strokes that this will take, and we'll have to wait until
we're in the water to determine that number), and will become our
standard for final flushes.

No...your "standard for final flushes" will be the number it takes to
move bowl contents from the bowl to their final destination...or at
least over the top of a vented loop if it's all downhill the rest of the
way.

However, I can't get rid of the standing water. What am I doing wrong
(or, is there an equipment problem?) such that I can't pump the
standing water out?

You're always gonna have a little left in the line to run back downhill.
The joker valve should reduce it to slow seepage, but it won't keep it
out of the bowl entirely.

I suggest you give Vic Willman at Raritan a call: 800-352-5630 x 6.

--
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://shop.sailboatowners.com/books...ku=90&cat=1304