Peggie: I'm getting ready to remove my forward holding tank and replace with a LectraSan for a variety of reasons. My current setup has a manual toilet with a vented loop on the intake line, then a short downward run of 1 1/2 inch tubing (Odorsafe) to the holding tank, then a short run to the macerator and out the thruhull. Total hose length involved is about 4 feet. The thruhull is about 2 inches below the waterline but the base of the toilet is about even with the waterline or maybe 1 inch above. My question is: do I really need a vented loop between the toilet and the thruhull? I'm aware of the need for protection at angles of heel but I've got two solutions: I close the thruhull prior to leaving the dock and I also have a ball valve which I plan to install at the toilet discharge in plain site. The ball valve will be closed unless the toilet is being used and then it will be closed again afterwards. Tell me what you think...thanks.
Do I really need a vented loop with a LectraSan?
- Thread starter Mark7500
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Yes! In fact, you may actually need two
You definitely need one in the L/S discharge, between it and the thru-hull...and unless you and anyone you'll ever have aboard can be counted on to close the shut-off valve between the toilet and L/S 100% of the time (90% or even 99% isn't good enough)--which we both know you cannot guarantee, you also need one between the toilet and the L/S instead of the valve. You also mentioned something else: "My current setup has a manual toilet with a vented loop on the intake line..." WHERE in the intake line--between the thru-hull and the toilet (wrong place for it), or between the pump and the bowl where it should be?
You definitely need one in the L/S discharge, between it and the thru-hull...and unless you and anyone you'll ever have aboard can be counted on to close the shut-off valve between the toilet and L/S 100% of the time (90% or even 99% isn't good enough)--which we both know you cannot guarantee, you also need one between the toilet and the L/S instead of the valve. You also mentioned something else: "My current setup has a manual toilet with a vented loop on the intake line..." WHERE in the intake line--between the thru-hull and the toilet (wrong place for it), or between the pump and the bowl where it should be?
Thruhulls
Peggie: Yes, my mistake--the intake thruhull is between the pump and the bowl on my current setup. Raritan shows a vented loop between the LectraSan and the discharge thruhull--fine, I understand that. But why do you need a second one between the LectraSan and the toilet if the toilet will always be higher than the LectraSan regardless of angle of heel? Thanks
Peggie: Yes, my mistake--the intake thruhull is between the pump and the bowl on my current setup. Raritan shows a vented loop between the LectraSan and the discharge thruhull--fine, I understand that. But why do you need a second one between the LectraSan and the toilet if the toilet will always be higher than the LectraSan regardless of angle of heel? Thanks
I dunno how that's possible on a sailboat
'Cuz where is there a bilge deep enough to keep the L/S below the toilet at any angle of heel? But assuming there is, what would be the purpose of the ball valve?
'Cuz where is there a bilge deep enough to keep the L/S below the toilet at any angle of heel? But assuming there is, what would be the purpose of the ball valve?
Toilet position
Peggie: Maybe I'm missing something obvious in my thinking about this problem? The toilet is mounted on a raised section of the head compartment floor which makes the bottom of the bowl about 2 inches higher than the top of the Lectrasan. Let's assume I'm going to put in a vented loop between the LectraSan and the discharge thruhull. Wouldn't the joker valve in the toilet be enough between the LectraSan and the toilet? The only way liquid can move back up the hose from the LectraSan to the toilet is if the boat is heeled more than about 40 degrees and also bow down--which is only a momentary position. The LectraSan unit's intake will be in the exact location that my holding tank intake currently is; I've had no problems with holding tank content coming back into the toilet ever, under lots of sailing conditions, and that hose is a nearly straight run downwards and outboard of the toilet. Thanks and sorry if I'm not understanding something obvious.
Peggie: Maybe I'm missing something obvious in my thinking about this problem? The toilet is mounted on a raised section of the head compartment floor which makes the bottom of the bowl about 2 inches higher than the top of the Lectrasan. Let's assume I'm going to put in a vented loop between the LectraSan and the discharge thruhull. Wouldn't the joker valve in the toilet be enough between the LectraSan and the toilet? The only way liquid can move back up the hose from the LectraSan to the toilet is if the boat is heeled more than about 40 degrees and also bow down--which is only a momentary position. The LectraSan unit's intake will be in the exact location that my holding tank intake currently is; I've had no problems with holding tank content coming back into the toilet ever, under lots of sailing conditions, and that hose is a nearly straight run downwards and outboard of the toilet. Thanks and sorry if I'm not understanding something obvious.
What you may be missing...
The inlet fitting in the L/S isn't on the top as it is in a holding tank...it's near the bottom. (it discharges by overflowing out the fitting on the top)...so unless the whole unit is WELL below the toilet, ANY heeling will send waste back toward the toilet--even more likely to if the inlet fitting is outboard of the toilet, 'cuz that's the direction the contents of the L/S will flow. And you don't want to rely solely on the joker valve in the toilet to keep it out of the bowl...that's not a what joker valve is designed to do. It IS supposed to prevent flooding, but it cannot prevent slow seepage. So if you're in open water on the same tack for an hour, without a loop in the line, you'll have some waste in the bowl. If you don't want to take my word for it that you need a loop in the head discharge line, give Vic Willman at Raritan a call: 800-352-5630 x 6.
The inlet fitting in the L/S isn't on the top as it is in a holding tank...it's near the bottom. (it discharges by overflowing out the fitting on the top)...so unless the whole unit is WELL below the toilet, ANY heeling will send waste back toward the toilet--even more likely to if the inlet fitting is outboard of the toilet, 'cuz that's the direction the contents of the L/S will flow. And you don't want to rely solely on the joker valve in the toilet to keep it out of the bowl...that's not a what joker valve is designed to do. It IS supposed to prevent flooding, but it cannot prevent slow seepage. So if you're in open water on the same tack for an hour, without a loop in the line, you'll have some waste in the bowl. If you don't want to take my word for it that you need a loop in the head discharge line, give Vic Willman at Raritan a call: 800-352-5630 x 6.
Thanks Peggie
Thanks Peggie-- I'm looking at the LectraSan right now and now it makes sense. I hate to keep at this but what about the alternative--if I put a vented loop between the toilet and the LectraSan intake, do I need a second one between the LectraSan and the discharge thruhull--I do close thruhulls before sailing. Thanks again--you're a wonderful resource on this board.
Thanks Peggie-- I'm looking at the LectraSan right now and now it makes sense. I hate to keep at this but what about the alternative--if I put a vented loop between the toilet and the LectraSan intake, do I need a second one between the LectraSan and the discharge thruhull--I do close thruhulls before sailing. Thanks again--you're a wonderful resource on this board.
You need loops in both locations, Mark
Aside from the fact that ALL lines connected to below-waterline thru-hulls should have a loop and siphon break installed to protect the boat from a sea water siphon, your L/S will be below waterline too...if not when the boat at rest, while heeled. Without a loop, there's nothing to prevent sea water from flooding the L/S.
Aside from the fact that ALL lines connected to below-waterline thru-hulls should have a loop and siphon break installed to protect the boat from a sea water siphon, your L/S will be below waterline too...if not when the boat at rest, while heeled. Without a loop, there's nothing to prevent sea water from flooding the L/S.
Between L/S and Head
Peggy I understand the need for the vented loop between the L/S and thru-hull. Why do you also need a vented loop between the L/S and the head. Thanks Good Winds Dave M s/v DAMWEGAS
Peggy I understand the need for the vented loop between the L/S and thru-hull. Why do you also need a vented loop between the L/S and the head. Thanks Good Winds Dave M s/v DAMWEGAS
Two or Three vented loops?
I have been following this threadd since I am about to install the LectraSan in my boat. It has no holding tanks at present, and no vented loops at all. On vented loops, I understand you need one from the lectrasan to the discharge thru-hull. I also think I am understanding the need for one between the pump and the bowl. Is one needed from the bowl discharge to the lectrasan?
I have been following this threadd since I am about to install the LectraSan in my boat. It has no holding tanks at present, and no vented loops at all. On vented loops, I understand you need one from the lectrasan to the discharge thru-hull. I also think I am understanding the need for one between the pump and the bowl. Is one needed from the bowl discharge to the lectrasan?
Yes.
Read post "What I think you may be missing" in this tread for the explanation. However, the vented loop in the toilet's flush water INTAKE (between the pump and the bowl) has nothing to do with a Lectra/San--or the toilet discharge at all. Its purpose is to keep sea water from the head INTAKE from overflowing the bowl...and is needed in any toilet that flushes with sea water if the bowl or any part of it is below the waterline. So you should have one no matter where the toilet discharge goes--into a tank, directly overboard, or through a Lectra/San.
Read post "What I think you may be missing" in this tread for the explanation. However, the vented loop in the toilet's flush water INTAKE (between the pump and the bowl) has nothing to do with a Lectra/San--or the toilet discharge at all. Its purpose is to keep sea water from the head INTAKE from overflowing the bowl...and is needed in any toilet that flushes with sea water if the bowl or any part of it is below the waterline. So you should have one no matter where the toilet discharge goes--into a tank, directly overboard, or through a Lectra/San.
3 loops, all vented??
I've attached a diagram (not professionally done) regarding the loops. I think everyone understands the two vented loops - the first and 3rd one. The middle loop is intended to keep sewage from sloshing back to the head. I've diagramed it without a vent but realize that the vent is there to prevent a vacuum from developing -- with a vent, liquid settles to the bottom of the loop, without one, the entire loop would remain full of liquid. My question is, if I put a vented loop in between the toilet and the lectrasan then I am going to be pumping the lecrasan full of air. It seems better, perhaps even safer for the unit if the middle loop is unvented. But, without the vent, the loop doesn't seem to do that much to isolate the toilet from the lectrasan. Other than showing the lectrasan located lower than the toilet (not a situation that is possible on a sailboat or in waves) the installation instructions just show a straight connection between toilet and lectrasan. So, thoughts?
I've attached a diagram (not professionally done) regarding the loops. I think everyone understands the two vented loops - the first and 3rd one. The middle loop is intended to keep sewage from sloshing back to the head. I've diagramed it without a vent but realize that the vent is there to prevent a vacuum from developing -- with a vent, liquid settles to the bottom of the loop, without one, the entire loop would remain full of liquid. My question is, if I put a vented loop in between the toilet and the lectrasan then I am going to be pumping the lecrasan full of air. It seems better, perhaps even safer for the unit if the middle loop is unvented. But, without the vent, the loop doesn't seem to do that much to isolate the toilet from the lectrasan. Other than showing the lectrasan located lower than the toilet (not a situation that is possible on a sailboat or in waves) the installation instructions just show a straight connection between toilet and lectrasan. So, thoughts?
Not how a vented loop works
" if I put a vented loop in between the toilet and the lectrasan then I am going to be pumping the lecrasan full of air." Nooo! 'Cuz a vented loop only PULLS air into a line through which liquid is also being PULLED. That's how it breaks a siphon. It cannot pull air into a line through which liquid is being PUSHED. Without a one-way air valve in the loop that only allows air to be pulled into the line, PUSHING liquid over the loop would only send the liquid squirting out the hole where the air valve should be. Neither the toilet pump nor the Lectra/San pulls anything out of the bowl...the toilet pump PUSHES the bowl contents through the discharge line. That's why any vented loop in a head intake must be between the pump and the bowl, not between the thru-hull and the pump...the toilet pump PULLS flush water TO the pump, which PUSHES it to the bowl. "with a vent, liquid settles to the bottom of the loop, without one, the entire loop would remain full of liquid." Not true either. (You never took high school physics, did you?) The loop--vented or not--has nothing to do with it, 'cuz it's above any water in the hose. The hose between the toilet and the top of the loop is a vertical pipe through which water is pushed by the toilet pump. That pipe is being filled from the bottom up...it has no place to settle. So if the hose between the toilet and the top of the loop is full--or even partially full--that water is either gonna stay in the hose or it's gonna drain back into the toilet bowl. But if you pump the toilet in the dry mode long enough to push everything in the bowl over the top of the loop (which any manual toilet CAN do), there won't be any water left in the uphill hose to the loop to run back downhill into the bowl. And since liquids always run downhill, any water that makes it over the top of the loop is gonna flow downhill...to a tank, or to a direct overboard thru-hull...or to the Lectra/San. My best advice: read and follow ALL the installation/operation instructions for the Lectra/San, whether you understand the reasons behind those instructions or not...or don't install one. 'Cuz 99.999% of problems with it are the result of failure to install it and/or operate it according to directions.
" if I put a vented loop in between the toilet and the lectrasan then I am going to be pumping the lecrasan full of air." Nooo! 'Cuz a vented loop only PULLS air into a line through which liquid is also being PULLED. That's how it breaks a siphon. It cannot pull air into a line through which liquid is being PUSHED. Without a one-way air valve in the loop that only allows air to be pulled into the line, PUSHING liquid over the loop would only send the liquid squirting out the hole where the air valve should be. Neither the toilet pump nor the Lectra/San pulls anything out of the bowl...the toilet pump PUSHES the bowl contents through the discharge line. That's why any vented loop in a head intake must be between the pump and the bowl, not between the thru-hull and the pump...the toilet pump PULLS flush water TO the pump, which PUSHES it to the bowl. "with a vent, liquid settles to the bottom of the loop, without one, the entire loop would remain full of liquid." Not true either. (You never took high school physics, did you?) The loop--vented or not--has nothing to do with it, 'cuz it's above any water in the hose. The hose between the toilet and the top of the loop is a vertical pipe through which water is pushed by the toilet pump. That pipe is being filled from the bottom up...it has no place to settle. So if the hose between the toilet and the top of the loop is full--or even partially full--that water is either gonna stay in the hose or it's gonna drain back into the toilet bowl. But if you pump the toilet in the dry mode long enough to push everything in the bowl over the top of the loop (which any manual toilet CAN do), there won't be any water left in the uphill hose to the loop to run back downhill into the bowl. And since liquids always run downhill, any water that makes it over the top of the loop is gonna flow downhill...to a tank, or to a direct overboard thru-hull...or to the Lectra/San. My best advice: read and follow ALL the installation/operation instructions for the Lectra/San, whether you understand the reasons behind those instructions or not...or don't install one. 'Cuz 99.999% of problems with it are the result of failure to install it and/or operate it according to directions.
fluid level in a vented loop
Drawing on my limited physics knowledge, this is what happens to fluids in a vented loop. The question is, is there problem in terms of only partially submerged plates with pumping air into the Lectrasan?
Drawing on my limited physics knowledge, this is what happens to fluids in a vented loop. The question is, is there problem in terms of only partially submerged plates with pumping air into the Lectrasan?
Doesn't matter whether the loop is vented or not..
The same thing will happen--water on the upside of it from the toilet to the top of the loop will either stay there or drain back into the toilet bowl...water on the downside of it will drain into the L/S, tank or to the waterline in a line connected directly to a thru-hull. If the toilet is flushed in the dry mode long enough to push the entire bowl contents over the top of the loop, the whole discharge line on both sides of the loop will be full of air...which will just be pushed out wherever it can get out--tank vent or discharge thru-hull...if out a below-waterline thru-hull, you may see a few bubbles. "The question is, is there problem in terms of only partially submerged plates with pumping air into the Lectrasan?" That's not an issue. The L/S doesn't empty with each flush...there is no pump in it, it remains full...so the electrode, mixer and macerator are always submerged. As your sketch shows, the inlet from the toilet is near the bottom (which is WHY a vented loop is needed between the toilet and the L/S on a sailboat...heeling can put it above the toilet)...the discharge is on the top. And it doesn't discharge as part of the treatment cycle...it discharges the next time the toilet is flushed. Each chamber has a 1.5 gal capacity...each flush (avg 1/2 gal, max 1 gal) displaces an equal volume already in it, moving it from the first chamber over the top of the divider into the second chamber, which in turn pushes the same amount out the discharge fitting. So it remains "full" all the time, just pushing treated waste--along with any air--out the dicharge fitting on the top as new waste comes in. Read the manual again: http://www.raritaneng.com/pdf_files/lectrasan/L270v0404.pdf
The same thing will happen--water on the upside of it from the toilet to the top of the loop will either stay there or drain back into the toilet bowl...water on the downside of it will drain into the L/S, tank or to the waterline in a line connected directly to a thru-hull. If the toilet is flushed in the dry mode long enough to push the entire bowl contents over the top of the loop, the whole discharge line on both sides of the loop will be full of air...which will just be pushed out wherever it can get out--tank vent or discharge thru-hull...if out a below-waterline thru-hull, you may see a few bubbles. "The question is, is there problem in terms of only partially submerged plates with pumping air into the Lectrasan?" That's not an issue. The L/S doesn't empty with each flush...there is no pump in it, it remains full...so the electrode, mixer and macerator are always submerged. As your sketch shows, the inlet from the toilet is near the bottom (which is WHY a vented loop is needed between the toilet and the L/S on a sailboat...heeling can put it above the toilet)...the discharge is on the top. And it doesn't discharge as part of the treatment cycle...it discharges the next time the toilet is flushed. Each chamber has a 1.5 gal capacity...each flush (avg 1/2 gal, max 1 gal) displaces an equal volume already in it, moving it from the first chamber over the top of the divider into the second chamber, which in turn pushes the same amount out the discharge fitting. So it remains "full" all the time, just pushing treated waste--along with any air--out the dicharge fitting on the top as new waste comes in. Read the manual again: http://www.raritaneng.com/pdf_files/lectrasan/L270v0404.pdf
Loops again
I've read the manual a few times and it doesn't advise a vented loop between the head and the Lectrasan. The instructions for the PHII toilet shows this arrangement when both the head and holding tank/Lectrasan are below the waterline. As you have pointed out, 'below the waterline' is a moving target in sailboats. With a vented loop between the toilet and the Lectrasan, you will introduce air into the Lectrasan unit. I'm not sure I agree with the point: "If the toilet is flushed in the dry mode long enough to push the entire bowl contents over the top of the loop, the whole discharge line on both sides of the loop will be full of air.." A vented loop on a sailboat, to be the recommended 4" above the water line when healing, has to be pretty high, at the top of the cockpit if it is on one side or the other, shorter if the loop is on the line of the keel. That is a high column of water to push through a 2 1/2" hose with air bubbles. I think the fluid would stay on the head side of the loop and bubbles would go over the top. I've attached another diagram pointing out that a loop between the toilet and the Lectrasan seems to accomplish little, particularly if it isn't as tall as the loop between the lectrasan and the discharge port. When I asked Vic today at Raritan, he advised: If both the head and the Lectra/San are above the waterline, there is no reason to have a vented loop between them, other than to stop backflow from the Lectra/San to the toilet bowl, should there be a partial clog somewhere in the system. You'd be better advised to have the vented loop between the Lectra/San and the through-hull fitting, with the top of the loop fitting a minimum of 4" above the waterline at the greatest "anticipated" angle of heel. There, it will act as a safety device to protect the boat from sinking of a plastic fitting, or the Lectra/San itself were to crack.
I've read the manual a few times and it doesn't advise a vented loop between the head and the Lectrasan. The instructions for the PHII toilet shows this arrangement when both the head and holding tank/Lectrasan are below the waterline. As you have pointed out, 'below the waterline' is a moving target in sailboats. With a vented loop between the toilet and the Lectrasan, you will introduce air into the Lectrasan unit. I'm not sure I agree with the point: "If the toilet is flushed in the dry mode long enough to push the entire bowl contents over the top of the loop, the whole discharge line on both sides of the loop will be full of air.." A vented loop on a sailboat, to be the recommended 4" above the water line when healing, has to be pretty high, at the top of the cockpit if it is on one side or the other, shorter if the loop is on the line of the keel. That is a high column of water to push through a 2 1/2" hose with air bubbles. I think the fluid would stay on the head side of the loop and bubbles would go over the top. I've attached another diagram pointing out that a loop between the toilet and the Lectrasan seems to accomplish little, particularly if it isn't as tall as the loop between the lectrasan and the discharge port. When I asked Vic today at Raritan, he advised: If both the head and the Lectra/San are above the waterline, there is no reason to have a vented loop between them, other than to stop backflow from the Lectra/San to the toilet bowl, should there be a partial clog somewhere in the system. You'd be better advised to have the vented loop between the Lectra/San and the through-hull fitting, with the top of the loop fitting a minimum of 4" above the waterline at the greatest "anticipated" angle of heel. There, it will act as a safety device to protect the boat from sinking of a plastic fitting, or the Lectra/San itself were to crack.
Vented Loops
The two crucial vented loops are between the toilet's pump and bowl - and between the output from the Lectra/San and the through-hull. The third one (between toilet and L/S) is optional, and not absolutely mandatory. You might wind up wind up flooding the bowl with "dirty water" from time to time, but you won't sink the boat. Keep in mind, that if the installation isn't according to factory specs, it gives the factory an "out," as far as warranty coverage should a problem ever develop.
The two crucial vented loops are between the toilet's pump and bowl - and between the output from the Lectra/San and the through-hull. The third one (between toilet and L/S) is optional, and not absolutely mandatory. You might wind up wind up flooding the bowl with "dirty water" from time to time, but you won't sink the boat. Keep in mind, that if the installation isn't according to factory specs, it gives the factory an "out," as far as warranty coverage should a problem ever develop.
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