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Old 21-08-2009, 12:30   #1
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New Lavac Explodes!

We have just had two new Lavac heads installed. They are wonderful except when the need comes to flush more than liquid. After solid waste has been flushed, I raise the lid and it has blasted the entire bowl and lid and seat with waste. Yuck!

I've tried different approaches to pumping. Have added water prior to a flush (there doesn't seem to be enough water in the bowl). 'Have at times pumped almost twice the times stated in the directions as it doesn't sound as if sufficient water is coming in (on the first 8-10 pumps). Have pumped slowly, quickly, or at high speed with no differences.

Our holding tank is above the height of the head in the forward part of the boat, below in the aft head. Both have the same problem.

And of course it is an intermittent problem!
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Old 21-08-2009, 12:38   #2
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Call the manufacturer. That is totally unacceptable.
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Old 21-08-2009, 12:50   #3
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A few qestions: 1.Do you have the proper plastic 'bleed' fitting in the hose? A hole that is too large may stop you from getting sufficient vacuum to draw in water.
2. The height of the holding tank shouldn't matter so long as you have a higher loop (as I believe is specified in the installation instructions) in the waste hose from the pump to the holding tank. Do you? 3. Is the vent for your holding tank clear? 4. Is the raw water seacock to the head open? 5. Are you able to lift the lid after you have pumped out, or does the vacuum keep it sealed (as it is supposed to) for a couple of minutes?

Typically, the problem with Lavac heads is that too much water is drawn in by the vacuum into the toilet bowl after pumping. It strikes me that your problem is likely one of five things: 1. insufficient water is getting to the toilet from the seacock (valve not fully open, or through-hull or hose plugged); 2. that the holding tank is not vented, creating pressure build-up in the tank and inlet hose (you could check that out by pumping with the deck pump-out fitting off); 3. the pump is clogged (unlikely, but easy to clean by removing the screw-off cover); 4. the venting hole is much too big (which you could check by coverning with tape). 5. The toilet seat/seat cover seals are not working/aligned properly. Try moving the seat around a bit and pushing down on it while you pump in order to check that out.

Good luck!

Brad
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Old 21-08-2009, 14:45   #4
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Holding tank not venting would be my guess. It would explain the lack of water As well I assume when you pump you get a seal at the seat so the seat is stuck to the point that you can't raise it with a gentle tug.
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Old 21-08-2009, 17:17   #5
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Not vented & using seawater stored too long? Have you tried fresh water & blue loo? May require an extra water tank but fresh water is better than sea water. Are you able to select direct discharge to sea? How does that work? Excess paper(thick multi layered) can block the valves in the pump. Cheap single ply is good.We have all had to learn the hard way!!

Best of luck Bill
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Old 02-09-2009, 23:12   #6
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I have a problem similar to Glenda2's: the Lavac fails to pump only SOLID waste. (It works fine with only liquid waste.) I've thought this was caused by some of the solid waste fouling the intake valve in the pump, keeping it slightly open. Then, when pumping continues, the diaphragm pumps waste back into the toilet. Does this sound right?

With the seat still closed, however, I can evacuate the toilet with the Whale Gusher pump downstream from the holding tank, which empties the tank overboard. This seems to indicate a plugged vent in the holding tank, or so I've surmised. (Good suggestion above to check this by removing the pumpout cap; I'll try that.)

Still puzzled, though, by the success of pumping liquid waste and the disaster of pumping solids. (And let me second the caveat about toilet paper. We've ALWAYS refrained from putting ANY toilet paper into marine heads--and the LaVac is the third brand we've used. The TP goes into a ziplock bag, never down the john.)

Any help and advice, in addition to the good replies above, will be much appreciated.

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Old 03-09-2009, 02:10   #7
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Good pump, plumbing, bad vent?

I'll go with those who blame the vent(s).

Sounds like you've pressurized the holding tank which has then blown the contents of the plumbing back into the bowl and upwards...

Could it be that the plumbing (esp. vents) was installed incorrectly?

I trust your pump has not been damaged.
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Old 03-09-2009, 06:09   #8
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Just read your original post & the comment about the water level is important. If the level is not about half then you will have trouble. I needed to remove the air bleed to get enough water in the bowl. Check the web site for instructions if you don't have them.
regards
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Old 03-09-2009, 06:19   #9
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Yuck, this sounds like a engineering solution which is half baked. Flushing a toilet is something a kid should be able to do.
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Old 03-09-2009, 08:35   #10
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Trouble pumping solids could be due to pipe restriction from buildup. Had the same problem on our head (not a Lavac, but doesn't matter), and found the 1+1/2" hose only had about 1/2" clear through one section of it. The ends of the hose looked fine, so I didn't suspect it at first.
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Old 03-09-2009, 09:44   #11
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Boracay, thanks. But the failure occurs only with solid waste. If the tank was pressurized, the failure would occur with exclusively liquid waste as well, wouldn't it?

This is what bugs me: the head seems to work perfectly with clean water--I can cycle it repeatedly with no problems. But solids seem to cause the problem of backflow. I tried dumping Tater Tots (the best approximation I could think of) into the head--and the backflow problem occurred immediately.

????
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Old 03-09-2009, 10:14   #12
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Clean hoses would pass the "tater tots". Restricted hoses would not, but would pass water.

Steve B.
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Old 03-09-2009, 10:33   #13
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Hey, Steve, thanks. (We're on Lopez Island, btw.) But the installation is brand new, and the exit lines are 1-1/2" PVC.
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Old 03-09-2009, 12:10   #14
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After pumping your bowl should pull a vacuum, certainly not pressure. Can you open the lid RIGHT AFTER PUMPING? You shouldn't be able to open it for awile. It should be held down tight via vacuum in the bowl for 10-15 seconds or so. My guess is your outlet hoses are restricted, hence liquid (no problem), solids (problem). Or the tank vent...
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Old 03-09-2009, 12:28   #15
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the pump at least on mine would not allow a back flow the flapper would be pushed hard against the seal.Something may be jammed in the pump.
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