Vented loop on Sealand Macerator

PascalG

PascalG

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I'm about to replace all 5 year old generic and permeated sanitation hose... in the process i will eliminate the Y valves and direct overboard discharge which will never be used anyway...

i'm trying to decide whether or not the vented loop on the macerator discharge is really needed considering that...
- the seacock is ALWAYS closed when the macerator is not running.
- teh pump is a Sealand and it seems to me that no or very little water could make it thru the 2 duckbills in the pump
- the heads are all Vacuflush and even if water could make it past the pump duckbills into the holding tank, it woudln't make it past the 4 duckbills of the heads and then past the bowl seal.

my goal is not just to simplify plumbing but also to elmininate any waste hose from living spaces, including under sink cabinet.

going to post a link to this thread in the Surveyor's forum to see if the lack of vented loop would be an ABYC issue.
 
Pascal,
Since you are eliminating the y valve, where would you plumb the overboard discharge? will you have a separate outlet from the tank to the macerator, or will you install a tee?
The best way is a separate outlet from the tank.
In all my sealand books, none show any vented loop.
If you discharge from the vacuum generator and go overboard, you must install a man made loop in the hose or piping higher than the waterline.
If you can get a book from sealand, i would highly recommend the super tech training manual for installations. It has many different diagrams that are very useful.
Also, you are better off using pvc plastic pipe where feasable to eliminate hose. Make sure all fittings are "sweep type" to not restrict flow. Barbed fittings are not recommended. good luck.
 
Pascal,

I am nearly positive that there is no vented loop in my 2 head Vacuflush system. Toilets connect directly to vacuum pumps (via pvc rigid pipe where possible) and then direclty to the holding tank. All of this is more or less on the same horizontal plane with no vent loop. I also have a macerator pump plumbed to a below-the-waterline through hull, but no vent in this circuit. In fact, this circuit is also basically all in the same horizontal plane and at or near the waterline with about a 2' drop to the trough hull. The holding tank has a vent to atmosphere which has a loop high up under the gunwhale (but not vented at the top). The only other connection to the holding tank is the deck discharge fitting. All of this is OEM by Sea Ray which claims to follow ABYC.
 
heads go to the tank, not overboard, I am eliminating the Y valves and direct overboard discharges.

my question is only about the line from the holding tank to the sealand pump to the thruhull. I'd like to get rid of the vented loop on that section. AFAIK, it should be fine since the to duckbills on the pump should prevent water from syphoning back. plus, in compliance with USCG rules, i never leave the seacock open anyway...
 
Since you are eliminating the y valve and overboard discharge, get rid of it all. plug the seacock inside with a male pipe plug, and remove pump and lines.
No vented loop is needed between the toilet and the tank.
 
I installed the same Sealand pump at the very end of the season. No loop and it works great. As long as the tank is adequately vented I didn't see why there would be a problem. The old macerator I removed didn't use a vented loop so I just swapped pumps out.

For those concerned, I tested it after my last pumpout and thorough flush out by the pumpout boat.
 
I vote no loop.

By the way, did you ever get a media filter for Charmer's watermaker? If not it occurred to me today that you might want to look at a bag type filter.
 
a bag type filter? no, since the WM works great except in plankton areas, we havent' done anything yet... maybe before we head back north...

the concern about the loop, has nothing to do about vents in the tank, it's to prevent syphoning water back into the tank once the pump is off. With an impeller macerator, you need a loop. With the sealand pump, i dont think so, yet i've seen them installed, hence my concern.
 
Yeah, a bag filter is just what it sounds like. A filter body that has a bag like element in it. The elements are relatively cheap, I've seen them as small as 1 micron (not that you would need one that fine) and in a pinch you can wash them out.

bagfilter-sm.jpg


PBHAssemblies-sm.jpg


Matrix sells them.
http://www.matrixdesalination.com/

But I bet you can find them online cheaper.

http://www.wcponline.com/PDF/Bag Filters.pdf

Pentek also makes some. Not sure if they make big ones though.

As to the pump. I wouldn't worry about the vented loop. I had a Sealand pumpout pump with no loop for years on my boat with no problems and I had the seacock open much of the time. As you've noted, it has 4 duck valves in it.
 
You stated that you keep the seacock closed so is it really an issue for you? Or are you worried about the next guy?

I keep my seacock closed as well so it's never an issue for me.
 
i want to do it right... mostly for whoever may operate the boat and not be as strict as i am in complying with black water rules (you'd be surprised how many boats run with discharge Yvalves/seacocks open/unlocked). Plus the what will a surveyor write up one day...

The sealand manual does not specify any vented loops, so i'm going to remove them.
 
my boat has a vented loop between the sealand pump and the thru hull. I doubt the maker would have installed it if it was not required. IIRC all lines below water line need a siphon breaker vented loop. I agree that as you use it it is not required but I’ll expect a surveyor would object and I don’t have the confidence in duck bills that yoy express.
 
Now that I think about it, my pump was mounted a bit above the water line. Can you do that?
 
quote:
Originally posted by PascalG

The sealand manual does not specify any vented loops, so i'm going to remove them.

Click to expand...


The vented loops isn't shown in the drawing but they do refer to it in the installation instructions.

http://www.sealandtechnology.com/pdf/600340678 Discharge pump instr.pdf

6. Vessels with an underwater discharge seacock or thru-hull must have a vented or anti-siphon loop
installed well above the water line between the pump outlet and the seacock or thru-hull. The ventedloop should be plumbed with hose to a thru-hull fitting well above the water line.
 
thks...

interesting, the diagram and the system instruction with the heads doens't mention a vented loop. interestingly, the existing vented loop is not connected to thurhull but vents... under the sink.

duh... now that i think of it, on my boat the vented loop for the overboard discharge is Tee'd into the tank vent... so, i guess i will have to move the vented loop to the stbd side so that i can tee it into the tank vent line...

Bill, can't move the pump above WL... all the plumbing is under the floor and below WL.
 
Mine works without the vented loop, FYI. Might not be to spec but that's how Ocean installed the original macerator.
 
if the issue is the vent hose to the sink, UGH!, what do you think about just relocating the vent? I dont think it matters how long the hose is.
 
As I understand it, the area where the vented loop is being questioned is from the holding tank to the "macerator" pump to the through-hull fitting.

"Legally," you should have a vented loop as the last item before the through-hull fitting if the pump, the tank itself, or the connecting hose is below the waterline. This is to protect the boat from sinking if a clamp comes off, hose breaks, pump cracks, etc. It'll make your insurance man happier...
 
thanks Vic... i think i will move the overboard discharge vented loop to the stbd side, near the holding tank vent filter and tee the vented loop into the vent line...
 
in the end i decided to remove the vented loop...

1)- from an operation point of view, the sea cock will never be left open. it's only opened when the discharge pump is turned on, which is pretty rare anyway
2)- when i replaced the hoses, i first pulled the hose on the inlet side of the discharge pump. Nothing came out, even though the 8' hose on the outlet side was full (everything spilled out when removed)
3)- after replacing the hoses and eliminating the loop, I left the seacock open for a day. nothing made it past the pump and the tankwatch remained on empty.

good enough for me...

i'll keep the vented loop hardware somewhere in case a surveyor makes a fuss about it in the future :-)
 
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