Head questions galore
 

Peggie Hall wrote:

wrote:

I just bought a new boat (to me) and have some head questions.


Hoooboy...:)

Head - Jabsco manual head

Now my problems and questions:

1. My toilet is filling up with water after it is pumped dry.


Most likely that's because the toilet is below the waterline, there is
no vented loop in the head intake, and you're leaving the pump in the
"wet" mode. See (download and print) the installation instructions and
operation manual for your toilet he
http://www.jabsco.com/prodInfo/overv...10-0000_ds.pdf


2. My holding tank seems to be filling up a lot faster than it should.
I have about a 20 gallon holding tank and it is full after a day sail
with light use. Keep in mind this includes a week's worth of sitting
without use.


Always flushing only in the "wet" mode and leaving the head intake
seacock open will do that.

3. I'm not familar with one part of the unit...Right next to the head
there is a manual pump. A hose comes in through a thru-hull and does a
loop that wraps back through the pump and to the holding tank. Is this
to pump out of the tank to the lake or the opposite?


I'm not sure from your description of it. Can you email me a photo or a
sketch of the installation? peg(dot)hall(at)sbcglobal(dot)net.

Any help would be appreciated.


Start by reading what passes for a manual at the link I gave you. I'll
be glad to answer any more questions after you've read it (and I'm 99%
sure your first will be "what's a vented loop?")


A vented loop can be made from half of a 2 part "P" trap intended
for use under your kitchen sink. The proper style has a drain plug
on it's normal bottom.

The plug may be fitted with a shraeder valve, like on your bicycle
inner tube or car wheel if you care to roll your own. The shraeder
valve must be adjusted for a very low pressure seal by adjusting it
with a shraeder valve tool. You should be able to blow through it,
but not suck.

The vented loop is created by mounting the trap upside down on the
top of two vertical pipes connected to the remainder of the piping
in use. If vibration tolerant couplings are used, rigid pipe may
couple to other piping, or semi flexible plastic pipe. I would use
an MJ, or mechanical joint Have used several with excellent results.
The MJ was invented for the Diefenbunker, nuclear defence against
toilets backing up with over pressure shock waves. The p trap should
be situated at a point that does not usually go below the waterline,
but that is negotiable. It's function is to allow low atmospheric
pressure inside the piping to "suck in" air, thus defeating any
syphon effect which would otherwise occur.

Proper anti syphon loops are available in cast platinum at marine
stores. Lesser metals like bronze are almost as expensive.

You should be able to see if the head is pumping water into it's
self when you pump the pump. If it is, flip the little lever switch
you will find if you look, and pumping again, observe the head is
pumped dry and your tank will not fill so quickly. This limits
slopping contents when at sea. I not, you will need to replace, or
possibly only clean the duck billed, or joker valve. Buy one, since
you will need a spare, then disassemble the pump to replace it. If
the old one is torn or warped you will need to replace it, if not,
you may be able to clean it. It would probably tear the day after
you return the un needed spare, or be just wrong enough that it
won't work if you need it. This should illustrate why it is called
a joker valve. The joke would be on you.

Three lobed valves mimic heart valves, but without ligaments, are
not as reliable as possible.

Crap overboard when you can. A flexible snow slider carpet may be of
assistance keeping topsides clear for neccessary bodily functions.
It can be towed by floating line to rinse, and seized up using the
commissionaire knot, a crochet, over the bulwark to be used.

That funny, unused alladin clip on the backstay is to permit a good
rig to suspend the stern ladder horizontally for use as a sea head
frame with backrest "sissy bars" support and dinghy dock towing
harness. The horse shoe MOB float makes a good seat cushion. With a
proper umbrella, a shower curtain, the times, a good cigar, LED
headlight and an ipod, how could life be better than with an
autopilot and self tacking jib?

Clinging desperate and naked to it, you are legal to do that for
which fishes and birds need no license.

A proper harness developed from this arrangement might enable a sea
bath under way, even body surfing. Rinse with a fresh water
washcloth to avoid salt water boils. Wash clothing during rainy
periods. There is never enough toilet paper at sea, Billy.

Terry K

Head questions galore
 

Thanks for all the info. I am familiar with the toilet and the wet/dry
mode. That definitely isn't the issue as I move the lever to dry after
each use. Even in the dry mode, water is entering the head.

As simple as it sounds, I believe the issue is that I've been leaving
the seacock during the week when I'm not using the boat. I guess I
need to close the seacock between uses as well. This is inconvenient,
but possible as I have pretty easy access to the seacock.

I am still not sure about the second pump that I have. I will take
pictures and send, but here's a bit better explanation of if:

The pump is a hand pump similar to a manual bilge pump. It forms an
upside down "T".

1. Hose enters boat through seacock and does a loop to about 5' in the
air. This is a 2nd seacock - not the one used for water to enter the
head. It is also larger. Probably 1 1/2" hose vs. the smaller used
for the head intake.
2. It goes back to form the stick part of the T.
3. On the "across" part of the T (bottom of pump), there is flow going
from holding tank to the pump out access on the deck.

I am assuming this is used to help push the material out and to flush
the system.

Head questions galore
 

Hobieshane wrote:

Thanks for all the info. I am familiar with the toilet and the wet/dry
mode. That definitely isn't the issue as I move the lever to dry after
each use. Even in the dry mode, water is entering the head.

As simple as it sounds, I believe the issue is that I've been leaving
the seacock during the week when I'm not using the boat.

It's actually two issues--open seacock AND the wet/dry cam in the pump
has failed...it's not cutting off the flow of flush water any more.
That's a VERY common problem in Jabsco toilets made in the 5-6 years,
due to either a design or tooling defect. And apparently Jabsco has no
intention of correcting it till the mold for that little part wears out.

It also provides an excellent illustration of why relying on the wet/dry
valve instead of closing the seacocks when leaving the boat is VERY
risky...'cuz while it's a common problem in Jabsco toilets, no toilet is
immune from wet/dry valve failure.

I guess I
need to close the seacock between uses as well. This is inconvenient,
but possible as I have pretty easy access to the seacock.

A vented loop in the head intake would prevent water from rising in the
bowl while the boat is at rest, but would not prevent it while the boat
is underway. So, yes...till you replace the wet dry valve--or better
yet, replace the toilet with one that's better quality--you will have to
keep the seacocks closed between uses while underway, but if you install
a loop, you could leave 'em open at the dock.

I am still not sure about the second pump that I have. I will take
pictures and send, but here's a bit better explanation of if:

The pump is a hand pump similar to a manual bilge pump. It forms an
upside down "T".

1. Hose enters boat through seacock and does a loop to about 5' in the
air. This is a 2nd seacock - not the one used for water to enter the
head. It is also larger. Probably 1 1/2" hose vs. the smaller used
for the head intake.

That's your head DISCHARGE...the hose EXITS the boat at that thru-hull.
There should be a y-valve in that line that allows you to choose between
flushing directly overboard or into the tank.

What passes for a manual for your toilet is on the Jabsco website he
http://www.jabsco.com/prodInfo/overv...UAL_TOILET.PDF
You can see a drawing and illustrations of typical installations...I
think if you compare those illustrations to what you have, what you have
will become a lot clearer.


2. It goes back to form the stick part of the T.
3. On the "across" part of the T (bottom of pump), there is flow going
from holding tank to the pump out access on the deck.
I am assuming this is used to help push the material out and to flush
the system.

None of that makes any sense...I'm gonna have to see some photos and
sketches of the plumbing runs to know what you have. What you SHOULD have:

3/4" ID hose from intake through-hull to the pump...at the back on the
bottom of the "compartment" that houses the wet/dry lever and cam.
There should be no loop in that line.

3/4" hose coming off the top of the pump to the inlet fitting on the
back of the bowl. The should be a vented loop in that line that's high
enough to be at least 6-8" above the waterline at any angle of
heel...but there may not be...it may be only a short piece of hose
between the pump and bowl.

Both the pump and the bowl rest on a cross piece called the base. It's
not a pump...the Jabsco manual only has one dual action pump.

1" or 1.5" hose off the back of the bottom of the pump that MAY go only
to a tank, or may go to a y-valve...one side of the y-valve up and over
a vented loop (same height as the intake loop) and to a thru-hull..the
other side to a fitting at or on the top of the tank.

1/5" hose coming off the tank at the bottom...it will either go directly
the deck pumpout fitting, or MAY go to either a y-valve or tee
fitting...one side to the deck pumpout fitting, the other side to a pump
(manual diaphragm...i.e. Whale Gusher, or electric macerator pump), then
up and over yet a 3rd vented loop to a thru-hull--which may be separate
from the direct toilet discharge thru-hull, or may be teed into that
line to use the same thru-hull.

If what you have is much different from that, it's plumbed incorrectly
and needs to be corrected...but I suspect that's pretty much what you
have--+/- some or all vented loops.

If you aren't sure what things like manual discharge pumps, macerators,
y-valves (aka diverter valves) and vented loops look like, do a search
for 'em on any of the marine retail sites.

--
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

Head questions galore
 

It's starting to make more sense now.

First, I need to replace my wet/dry cam.

Second, It looks like I have two options for pumping out the holding
tank: 1. Through the deck fitting or 2. Through the 1.5" hose exiting
the hull next to the fresh water intake seacock.

The whale pump appears to pump from the tank, go through a vented loop,
and exit the thru-hull. What I am still confused about is that the
pump out deck hose is connected to this as well. Is it as simple as
when the thru-hull is open, the whale pumps out through it? Otherwise,
I would pump out through the deck fitting.

I do want to note to everyone that I know to not pump directly to the
lake as I am inland.

Head questions galore
 

Hobieshane wrote:

First, I need to replace my wet/dry cam.

Sincee that may cost you half the price of whole new Jabsco toilet
(which gives you an idea of their quality), I'd replace the whole toilet
with a better one if it were my boat...but that's up to you.

The whale pump appears to pump from the tank, go through a vented loop,
and exit the thru-hull. What I am still confused about is that the
pump out deck hose is connected to this as well. Is it as simple as
when the thru-hull is open, the whale pumps out through it? Otherwise,
I would pump out through the deck fitting.

If there's only a tee or wye fitting in that line, yup...it's that
simple. If there's a y-valve, it's almost that simple...you just have to
turn the handle on the y-valve to direct the flow from the tank to the
pump instead of the deck pumpout fitting.

However, I forgot to mention one more hose that comes off the tank: the
tank vent line, which will come off the tank at or on the top and go to
an above-waterline thru-hull fitting (btw, all your tanks--water, waste
and fuel--have vents, so this applies to 'em all) that'll most likely be
somewhere near the toe rail. It's essential to make sure the vent line
never becomes clogged...'cuz if it does, air displaced by incoming
flushes has nowhere to escape...the tank will become pressurized--which
can have disastrous consequences, from an eruption in the toilet or out
the deck pumpout fitting to a burst tank--and it will also be impossible
to empty the tank, because the pumpout will pull a vacuum. A strong
pumpout can even implode a tank. So check your vent thru-hull
regularly...backflush it each time you pumpout and/or wash the boat. And
cease all use of the toilet immediately if you start to experience
increasing backpressure or the toilet "burps" or backs up till the vent
has been cleared.

I do want to note to everyone that I know to not pump directly to the
lake as I am inland.

In that case, you need to check with local law enforcement to find out
whether you'll have remove the manual pump and all plumbing from the
toilet and/or tank to the overboard discharge thru-hulls. Although
simply "securing" the system from "accidental" overboard discharge as
prescribed by federal law is legal in coastal waters, some states have
made it illegal even to have the ability to discharge the toilet or tank
on inland waters.

As a new Hunter owner, you might want to check out this site:
http://www.hunterowners.com/index.htm I think you'll enjoy it AND learn
a lot from the other owners there.


--
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

Head questions galore
 

Actually, at the time I didn't know better, so I did not install a vented
loop. I'm sure I thought you couldn't put one on the intake side. (This was
a catamaran, so heeling didn't make the risk greater. ) Now that I think
about it, the survey (it was a 6 month old demonstrator boat) didn't make
mention of this deficiency.

But let me ask you about a related "theory" I have. My old boat w/o a vented
loop had very little odor from the raw water after the head had not been
used for a week or two or more. Only briefly after the first flush. My
present boat w/ a vented loop has a much stronger odor from the raw water
for many flushes. The longer raw water line because of the way the vented
loop is run must affect this, but I wonder if the contact with air in the
vented loop doesn't cause a greater odor problem ?

"Peggie Hall" wrote in message
. net...
Garland Gray II wrote:

I figured the rubber valve at top of the pump could leak and bypass
water. And you are certainly right about the possibility of the lever
being left in the wet position. My old boat csme with no vented loop, and
if someone was careless, the water would nearly fill the bowl.

So it's safe to assume that you DID install a vented loop? Which, btw,
should NOT be installed in the intake line between the thru-hull and the
pump..it has to go between the pump and the bowl...to replace the short
piece of hose the mfr uses to connect 'em. There are exceptions...electric
macerating toilets--in which case it's necessary to add an electric
solenoid valve--and some very high end manual toilets that have dual pumps
and don't have that short piece of hose.
--
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

Head questions galore
 

Thanks !

"Terry Spragg" wrote in message
.. .
Peggie Hall wrote:

wrote:

I just bought a new boat (to me) and have some head questions.


Hoooboy...:)

Head - Jabsco manual head

Now my problems and questions:

1. My toilet is filling up with water after it is pumped dry.


Most likely that's because the toilet is below the waterline, there is no
vented loop in the head intake, and you're leaving the pump in the "wet"
mode. See (download and print) the installation instructions and
operation manual for your toilet he
http://www.jabsco.com/prodInfo/overv...10-0000_ds.pdf


2. My holding tank seems to be filling up a lot faster than it should.
I have about a 20 gallon holding tank and it is full after a day sail
with light use. Keep in mind this includes a week's worth of sitting
without use.


Always flushing only in the "wet" mode and leaving the head intake
seacock open will do that.

3. I'm not familar with one part of the unit...Right next to the head
there is a manual pump. A hose comes in through a thru-hull and does a
loop that wraps back through the pump and to the holding tank. Is this
to pump out of the tank to the lake or the opposite?


I'm not sure from your description of it. Can you email me a photo or a
sketch of the installation? peg(dot)hall(at)sbcglobal(dot)net.

Any help would be appreciated.


Start by reading what passes for a manual at the link I gave you. I'll be
glad to answer any more questions after you've read it (and I'm 99% sure
your first will be "what's a vented loop?")


A vented loop can be made from half of a 2 part "P" trap intended for use
under your kitchen sink. The proper style has a drain plug on it's normal
bottom.

The plug may be fitted with a shraeder valve, like on your bicycle inner
tube or car wheel if you care to roll your own. The shraeder valve must
be adjusted for a very low pressure seal by adjusting it with a shraeder
valve tool. You should be able to blow through it, but not suck.

The vented loop is created by mounting the trap upside down on the top of
two vertical pipes connected to the remainder of the piping in use. If
vibration tolerant couplings are used, rigid pipe may couple to other
piping, or semi flexible plastic pipe. I would use an MJ, or mechanical
joint Have used several with excellent results. The MJ was invented for
the Diefenbunker, nuclear defence against toilets backing up with over
pressure shock waves. The p trap should be situated at a point that does
not usually go below the waterline, but that is negotiable. It's function
is to allow low atmospheric pressure inside the piping to "suck in" air,
thus defeating any syphon effect which would otherwise occur.

Proper anti syphon loops are available in cast platinum at marine stores.
Lesser metals like bronze are almost as expensive.

You should be able to see if the head is pumping water into it's self when
you pump the pump. If it is, flip the little lever switch you will find
if you look, and pumping again, observe the head is pumped dry and your
tank will not fill so quickly. This limits slopping contents when at sea.
I not, you will need to replace, or possibly only clean the duck billed,
or joker valve. Buy one, since you will need a spare, then disassemble
the pump to replace it. If the old one is torn or warped you will need to
replace it, if not, you may be able to clean it. It would probably tear
the day after you return the un needed spare, or be just wrong enough that
it won't work if you need it. This should illustrate why it is called a
joker valve. The joke would be on you.

Three lobed valves mimic heart valves, but without ligaments, are not as
reliable as possible.

Crap overboard when you can. A flexible snow slider carpet may be of
assistance keeping topsides clear for neccessary bodily functions. It can
be towed by floating line to rinse, and seized up using the commissionaire
knot, a crochet, over the bulwark to be used.

That funny, unused alladin clip on the backstay is to permit a good rig to
suspend the stern ladder horizontally for use as a sea head frame with
backrest "sissy bars" support and dinghy dock towing harness. The horse
shoe MOB float makes a good seat cushion. With a proper umbrella, a shower
curtain, the times, a good cigar, LED headlight and an ipod, how could
life be better than with an autopilot and self tacking jib?

Clinging desperate and naked to it, you are legal to do that for which
fishes and birds need no license.

A proper harness developed from this arrangement might enable a sea bath
under way, even body surfing. Rinse with a fresh water washcloth to avoid
salt water boils. Wash clothing during rainy periods. There is never
enough toilet paper at sea, Billy.

Terry K

Head questions galore
 

Garland Gray II wrote:
Actually, at the time I didn't know better, so I did not install a
vented loop. I'm sure I thought you couldn't put one on the intake
side. (This was a catamaran, so heeling didn't make the risk
greater. ) Now that I think about it, the survey (it was a 6 month
old demonstrator boat) didn't make mention of this deficiency.

If the toilet is completely above the waterline, it wasn't.


But let me ask you about a related "theory" I have. My old boat w/o a
vented loop had very little odor from the raw water after the head
had not been used for a week or two or more. Only briefly after the
first flush. My present boat w/ a vented loop has a much stronger
odor from the raw water for many flushes. The longer raw water line
because of the way the vented loop is run must affect this, but I
wonder if the contact with air in the vented loop doesn't cause a
greater odor problem ?

The longer head intake line is likely to be the cause, because the
longer the line, the more sea water is left in it to sit and stagnate.
But the vented loop has nothing to do with it. For one thing, it doesn't
passively allow any air into the line, it only pulls air into a line
through which water is actively being pulled. But even if it did, adding
air (oxygen) would reduce odor, not increase it...'cuz the more aerobic
the conditions, the less odor can be produced.

However, if the vented loop is in the intake line between the thru-hull
and the pump, it is likely to create another problem: interfere with the
pump's ability to prime by introducing air into the line that the pump
is trying to start by priming. It needs to be between the pump and the
bowl where it can't interfere with toilet flushing because flush water
is being pushed, not pulled, from the pump to the bowl.
--
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

Head questions galore
 

Wait a sec...

A vented loop can be made from half of a 2 part "P" trap intended for use
under your kitchen sink. The proper style has a drain plug on it's normal
bottom.

The plug may be fitted with a shraeder valve, like on your bicycle inner
tube or car wheel if you care to roll your own. The shraeder valve must
be adjusted for a very low pressure seal by adjusting it with a shraeder
valve tool. You should be able to blow through it, but not suck.

If I'm understanding what you're saying, it should be just the
opposite...'cuz the function of a vented loop is twofold...1) it creats
an arch in the line above the waterline...and 2) it's suppose only alow
INTO a line, nothing out.

The vented loop is created by mounting the trap upside down on the top of
two vertical pipes connected to the remainder of the piping in use. If
vibration tolerant couplings are used, rigid pipe may couple to other
piping, or semi flexible plastic pipe. I would use an MJ, or mechanical
joint Have used several with excellent results. The MJ was invented for
the Diefenbunker, nuclear defence against toilets backing up with over
pressure shock waves. The p trap should be situated at a point that does
not usually go below the waterline, but that is negotiable. It's function
is to allow low atmospheric pressure inside the piping to "suck in" air,
thus defeating any syphon effect which would otherwise occur.

Wouldn't it be a lot simpler and cheaper to simply drill a hole in the
trap and buy an air valve to put in the hole?

Proper anti syphon loops are available in cast platinum at marine stores.
Lesser metals like bronze are almost as expensive.

PVC vented loops are also availalble, and priced pretty reasonably.


You should be able to see if the head is pumping water into it's self when
you pump the pump. If it is, flip the little lever switch you will find
if you look, and pumping again, observe the head is pumped dry and your
tank will not fill so quickly.

Simply put, the most water efficient way: ahead of use, pump the head a
couple of times to wet the bowl...switch to dry. After use, pump enough
times in the dry mode to move the bowl contents all the way to the tank
(or out the thru-hull if at sea beyond the "3 mile limit")...switch to
"wet" for only enough pumps to rinse the bowl...then back to "dry" to
pump the "rinse water" all the way through the system.

Before you ask...any marine toilet that's working anywhere near spec can
move bowl contents at least 6' in the dry mode. If your tank or
thru-hull is significantly further away than 6', it's a badly designed
system.

you will need to replace, or possibly only clean the duck billed,
or joker valve.

As a live-aboard, replace it once a year...the average "weekend warrior"
should replace it at least every two years.

Buy one, since you will need a spare, then disassemble
the pump to replace it.


Why should you need to do that? The joker valve is in the head discharge
fitting, which isn't part of the pump, but only attached to it.
Replacing a joker valve only requires removing the screws that hold the
discharge fitting onto the pump.

If the old one is torn or warped you will need to
replace it, if not, you may be able to clean it.

If it's more than a year or two old, the slit will no longer be a slit,
but a hole...no longer able to function as the one-way valve it's
designed to be. Regardless of any other condition, if you can see ANY
daylight when you look through it, replace it.

I've never seen one torn that shouldn't have been replaced at least a
decade earlier.


Three lobed valves mimic heart valves, but without ligaments, are not as
reliable as possible.

Joker valves don't have lobes...the most common are a cup with a single
slit...a few are a cup with a + in the bottom instead of a slit...but
they're all just cup shaped doodads with a flange (that doubles as the
gasket between the fitting and the pump), a single - or + slits in the
bottom, and "lips" on the outside of the cup.

Crap overboard when you can. A flexible snow slider carpet may be of
assistance keeping topsides clear for neccessary bodily functions. It can
be towed by floating line to rinse, and seized up using the commissionaire
knot, a crochet, over the bulwark to be used.

Wouldn't a bucket on a long line be a lot cleaner and easier?

As for the rest...you have a wonderful imagination, Terry..but not a lot
of practical experience. If I'm wrong about that last part, please send
demonstration videos shot in 4-6' seas at least 20 miles
offshore...I'll add narration, send 'em to "America's Funniest..." and
split the take with you. :)

--
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

Head questions galore
 

"Peggie Hall" wrote in message
. net...
Garland Gray II wrote:
Actually, at the time I didn't know better, so I did not install a
vented loop. I'm sure I thought you couldn't put one on the intake
side. (This was a catamaran, so heeling didn't make the risk
greater. ) Now that I think about it, the survey (it was a 6 month
old demonstrator boat) didn't make mention of this deficiency.

If the toilet is completely above the waterline, it wasn't.


It was almost completely below waterline.




But let me ask you about a related "theory" I have. My old boat w/o a
vented loop had very little odor from the raw water after the head
had not been used for a week or two or more. Only briefly after the
first flush. My present boat w/ a vented loop has a much stronger
odor from the raw water for many flushes. The longer raw water line
because of the way the vented loop is run must affect this, but I
wonder if the contact with air in the vented loop doesn't cause a
greater odor problem ?

The longer head intake line is likely to be the cause, because the longer
the line, the more sea water is left in it to sit and stagnate. But the
vented loop has nothing to do with it. For one thing, it doesn't passively
allow any air into the line, it only pulls air into a line through which
water is actively being pulled. But even if it did, adding air (oxygen)
would reduce odor, not increase it...'cuz the more aerobic the conditions,
the less odor can be produced.


I expect that the water between the vented loop and the bowl that is higher
than the top of the bowl eventually drains to the bowl, to be replaced by
air. But I'll trust your knowledge of bacteria.



However, if the vented loop is in the intake line between the thru-hull
and the pump, it is likely to create another problem: interfere with the
pump's ability to prime by introducing air into the line that the pump is
trying to start by priming. It needs to be between the pump and the bowl
where it can't interfere with toilet flushing because flush water is being
pushed, not pulled, from the pump to the bowl.
--
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