I have a Lavac marine toilet on my sailboat. It works very well. With the Henderson Mark5 bilge pump that is part of the Lavac, plus three Y valves, I not only can pump the toilet into either the holding tank or overboard, but can also pump the holding tank or the bilges overboard. My only complaint is that the Lavac uses about a gallon with each flush. Blakes, the manufacturer, claims the toilet only uses three pints per flush. Quite a discrepancy. I follow the instructions that came with the toilet: 8 strokes of the pump; wait 5 seconds; then 5 more strokes. I am wondering whether I could get away with fewer strokes (just enough to clear the toilet bowl, for instance) for most flushes, then do the whole 8 + 5 stroke routine once a day. What do you think? Would that just lead to stinky hoses in a short time, or would a daily full flush avoid that?
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It's working too well.
No, it works "too well." It always pumps clean. The cover seals perfectly. The owners manual recommends you pump eight full strokes, wait five seconds, then pump another five strokes. The pump supplied is a Henderson Mk-5 bilge pump rated at 16 gal. per minute. Here are a few calculations: 1.5" ID sanitation hose contains .091 gallons of water per foot. There are 3.5 feet of hose between my toilet and the pump. The 3.5 feet of hose, therefore, contain .318 gallons. The toilet bowl contains a pint of water, which is .125 gallons Total water ahead of pump = .318 gal. + .125 gal. = .443 gal. This pump draws so powerfully, that it most likely draws additional water from the intake while I am pumping, so it is likely that the eight strokes cause a half a gallon to pass through the pump. The suction created is so strong, that everything fills up again during the five seconds delay, and the final five strokes probably empty out another half gallon. A system that can move that much water is very good, I would imagine, for avoiding clogs and minimizing odors. The disadvantage is having a holding tank that must be frequently emptied. I am wondering if I can get away with operating the system at less than "full throttle" on most flushes, with a full flush once in a while to completely clear the system. For example, 2 flushes + 5 seconds, + 2 flushes would very nicely clear the bowl.
No, it works "too well." It always pumps clean. The cover seals perfectly. The owners manual recommends you pump eight full strokes, wait five seconds, then pump another five strokes. The pump supplied is a Henderson Mk-5 bilge pump rated at 16 gal. per minute. Here are a few calculations: 1.5" ID sanitation hose contains .091 gallons of water per foot. There are 3.5 feet of hose between my toilet and the pump. The 3.5 feet of hose, therefore, contain .318 gallons. The toilet bowl contains a pint of water, which is .125 gallons Total water ahead of pump = .318 gal. + .125 gal. = .443 gal. This pump draws so powerfully, that it most likely draws additional water from the intake while I am pumping, so it is likely that the eight strokes cause a half a gallon to pass through the pump. The suction created is so strong, that everything fills up again during the five seconds delay, and the final five strokes probably empty out another half gallon. A system that can move that much water is very good, I would imagine, for avoiding clogs and minimizing odors. The disadvantage is having a holding tank that must be frequently emptied. I am wondering if I can get away with operating the system at less than "full throttle" on most flushes, with a full flush once in a while to completely clear the system. For example, 2 flushes + 5 seconds, + 2 flushes would very nicely clear the bowl.
Surprise--The toilet is using just about what the directions say it should use
You estimate the toilet uses .443 gal. flush water. A gallon is 128 oz. 128 x .443 = 56.7404 oz. A pint is 16 oz. 56.7404 / 16 = 3.544 pints...which is almost exactly the amount of flush water the directions say the toilet is supposed to use. How big is your tank, and how many people are typically aboard for how long? Here's the math to figure out how long it should take to fill up your tank: The average adult uses the toilet 5x/day. Avg output 8 oz plus flush water--which on your boat would be close to .5/gal/flush or 2.5 gal/day/person. So X people x 2.5 is the volume (gals.) going into the tank each. Divide your tank capacity by that number and you get the number of days it takes to fill up your tank. I have a feeling the result will surprise you. Your waters are NOT "no discharge"...the discharge of treated waste is legal (and more environmentally friendly than holding tanks). So you might consider installing a Type I MSD (treatment device) so you can stop using the tank and not have to bother with pumpouts any more.
You estimate the toilet uses .443 gal. flush water. A gallon is 128 oz. 128 x .443 = 56.7404 oz. A pint is 16 oz. 56.7404 / 16 = 3.544 pints...which is almost exactly the amount of flush water the directions say the toilet is supposed to use. How big is your tank, and how many people are typically aboard for how long? Here's the math to figure out how long it should take to fill up your tank: The average adult uses the toilet 5x/day. Avg output 8 oz plus flush water--which on your boat would be close to .5/gal/flush or 2.5 gal/day/person. So X people x 2.5 is the volume (gals.) going into the tank each. Divide your tank capacity by that number and you get the number of days it takes to fill up your tank. I have a feeling the result will surprise you. Your waters are NOT "no discharge"...the discharge of treated waste is legal (and more environmentally friendly than holding tanks). So you might consider installing a Type I MSD (treatment device) so you can stop using the tank and not have to bother with pumpouts any more.
No, it uses twice what the instructions say.
The Lavac comes with sticker that is to be posted on the bulkhead beside the pump. It directs the user to flush in the following manner: 1. Pump 8 full strokes. 2. Wait 5 seconds. 3. Pump 5 additional strokes. The first 8 strokes pump at least .443 gallons. The second 5 also pump at least .443 gallons. So, by caculation, it uses at least .886 gallons per flush. To verify this, I have run an experiment, counting flushes from an empty tank to a full tank. I count 19 flushes. I know from design, measurement and from directly filling the tank from a one gallon jug, that the tank holds 22 gallons. All data indicate that when flushed according to the manufacturer's instructions, the Lavac uses about a gallon per flush. In a previous post, you said that since a Lavac is vacuum head, I should just have to pump it a couple of strokes to clear the bowl. This is much less pumping that the manufacturer recommends, but its sounds like a practical solution to me. Thanks for the advice.
The Lavac comes with sticker that is to be posted on the bulkhead beside the pump. It directs the user to flush in the following manner: 1. Pump 8 full strokes. 2. Wait 5 seconds. 3. Pump 5 additional strokes. The first 8 strokes pump at least .443 gallons. The second 5 also pump at least .443 gallons. So, by caculation, it uses at least .886 gallons per flush. To verify this, I have run an experiment, counting flushes from an empty tank to a full tank. I count 19 flushes. I know from design, measurement and from directly filling the tank from a one gallon jug, that the tank holds 22 gallons. All data indicate that when flushed according to the manufacturer's instructions, the Lavac uses about a gallon per flush. In a previous post, you said that since a Lavac is vacuum head, I should just have to pump it a couple of strokes to clear the bowl. This is much less pumping that the manufacturer recommends, but its sounds like a practical solution to me. Thanks for the advice.
Something isn't right...
"The first 8 strokes pump at least .443 gallons. The second 5 also pump at least .443 gallons." The second 5 strokes brings in as much flush water as the first 8???? If that's true, something is wrong. I see no reason why you can't try doing it your way...if it works, fine. If it doesn't, it doesn't. But I also think you should have a chat with folks at St. Brendans Isle to find out why the toilet is using more flush water than it should when used as directed. "Why do keep telling me that I am not following instructions? Why don't you just answer my question?" I'm not psychic...without actually seeing your installation, I don't know what the problem is...I have only what you tell me to go on....and SOMETHING has to be wrong--either with your use of the toilet or the installation--for a Lavac to use more than the +/- 3 pints specified. I should have just given you the contact info for St. Brendans Isle, told you to call them, and been done with it instead of wasting my time trying sort out the problem for you.
"The first 8 strokes pump at least .443 gallons. The second 5 also pump at least .443 gallons." The second 5 strokes brings in as much flush water as the first 8???? If that's true, something is wrong. I see no reason why you can't try doing it your way...if it works, fine. If it doesn't, it doesn't. But I also think you should have a chat with folks at St. Brendans Isle to find out why the toilet is using more flush water than it should when used as directed. "Why do keep telling me that I am not following instructions? Why don't you just answer my question?" I'm not psychic...without actually seeing your installation, I don't know what the problem is...I have only what you tell me to go on....and SOMETHING has to be wrong--either with your use of the toilet or the installation--for a Lavac to use more than the +/- 3 pints specified. I should have just given you the contact info for St. Brendans Isle, told you to call them, and been done with it instead of wasting my time trying sort out the problem for you.
Try a Lavac sometime. You might learn something.
Try a Lavac sometime. You might learn something. It's a great toilet. It comes with a huge pump. That pump moves a lot of water. It can't do otherwise. Your inability to understand how a Lavac works makes me doubt the rest of your advice.
Try a Lavac sometime. You might learn something. It's a great toilet. It comes with a huge pump. That pump moves a lot of water. It can't do otherwise. Your inability to understand how a Lavac works makes me doubt the rest of your advice.
Lavac Toilet
The main issue with the Lavac head is that is intended for use on sailboats that spend most of their lives in international waters, where it is legal to discharge directly over the side. Whether it uses 3 pints or 6 pints per flush, and fills up a holding tank too quickly for anyone's comfort, is really a moot point. The Lavac toilet predates the common use of holding tanks by many years, and holding tank sizes and capacities weren't even thought about when the Lavac was originally designed. I'd have to say that if you can clear the bowl in 1/2 the number of strokes as recommended, by all means do it! But at least once a day, go ahead and follow their recommendations, to be sure all the lines have been purged, and there's no sewage still laying in the lines.
The main issue with the Lavac head is that is intended for use on sailboats that spend most of their lives in international waters, where it is legal to discharge directly over the side. Whether it uses 3 pints or 6 pints per flush, and fills up a holding tank too quickly for anyone's comfort, is really a moot point. The Lavac toilet predates the common use of holding tanks by many years, and holding tank sizes and capacities weren't even thought about when the Lavac was originally designed. I'd have to say that if you can clear the bowl in 1/2 the number of strokes as recommended, by all means do it! But at least once a day, go ahead and follow their recommendations, to be sure all the lines have been purged, and there's no sewage still laying in the lines.
Alan
The FAQs on the Lavac site suggest you can empty the bowl (for sailing) by leaving the lid open. In other words when the pump is not pulling a vacuum it will move water into and out of the bowl. I would really check the seal between the lid and the bowl. If you need any parts you can get them from Marine Sanitation in Seattle who can also offer some advice on this and most other brands of head. I tend to agree with Vic on this one. Why not experiment on the fewest no. of strokes it takes to evacuate the bowl?
The FAQs on the Lavac site suggest you can empty the bowl (for sailing) by leaving the lid open. In other words when the pump is not pulling a vacuum it will move water into and out of the bowl. I would really check the seal between the lid and the bowl. If you need any parts you can get them from Marine Sanitation in Seattle who can also offer some advice on this and most other brands of head. I tend to agree with Vic on this one. Why not experiment on the fewest no. of strokes it takes to evacuate the bowl?
Four strokes are enough
Tom, Vic: I performed an experiment yesterday, progressively reducing the number of strokes required to clear the bowl and the segment of tubing that lies between bowl and pump. Four strokes are sufficient. With four strokes, I get 80 flushes before the holding tank fills, as opposed to only 19 flushes from the 13 strokes recommended by the manufacturer. There's nothing wrong with my cover seals. That's why my Lavac works so efficiently. When the toilet seat is closed on a Lavac, thus sealing the bowl, water passes directly from the input seacock to the 16 gpm Henderson bilge pump with no intervening parts to impede the flow. I completely agree on Marine Sanitation being a great asset here in Seattle. I've spent several hundreds of dollars there on Sea Land skin fittings and TankWatch-4 monitor and am well satisfied with the value received.
Tom, Vic: I performed an experiment yesterday, progressively reducing the number of strokes required to clear the bowl and the segment of tubing that lies between bowl and pump. Four strokes are sufficient. With four strokes, I get 80 flushes before the holding tank fills, as opposed to only 19 flushes from the 13 strokes recommended by the manufacturer. There's nothing wrong with my cover seals. That's why my Lavac works so efficiently. When the toilet seat is closed on a Lavac, thus sealing the bowl, water passes directly from the input seacock to the 16 gpm Henderson bilge pump with no intervening parts to impede the flow. I completely agree on Marine Sanitation being a great asset here in Seattle. I've spent several hundreds of dollars there on Sea Land skin fittings and TankWatch-4 monitor and am well satisfied with the value received.
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