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Old 08-04-2008, 10:23   #1
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Lavac install - elbow seal

Heya all -

I have 2 questions - I've bought a Lavac Popular head to replace the old junk one. I've installed it, and used an elbow a few inches out of the discharge (that goes to the pump) as the sanitation pipe couldn't bend enough (there wasn't enough clearance between the back of the head and the wall.) So it basically goes from discharge, 3 " of pipe, elbow, then another 6" to the bottom of the diaphragm pump.

Everything works great, and I have the feeling I could use cardboard for toilet paper and it'd suck it right out without jamming! (not that I'm trying that!) I have noticed that the elbow sometimes feels damp after pumping. The elbow didn't fit very tightly with the hose, but was definitely the right piece (it wasn't a size too small or anything). It's a standard plastic (non barbed) male elbow, and is double hose clamped tightly at both ends. I'm using the standard white 1.5" sanitation hose. Any ideas on how best to stop this? Could I use plumbers putty or teflon tape or something for a better seal?

Second question - after pumping, the bowl fills about 3/4 of the way with water. Is this the same for everyone? I've looped the raw water at a high point to avoid problems when heeling, but I didn't vent it. Do I need to do that, or is that just normal for a Lavac?

Many thanks for any suggestions!
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Old 08-04-2008, 13:16   #2
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You need a vent in the inlet line, the size of the hole will determine the level in the bowl. If you use a proprietry vent elbow with the ducks bill venting piece it will give you around 1/2 to 3/4 of a bowl of water. I machined up a couple of pieces out of nylon stock and progressively drilled the hole until I had about 1/4 of the bowl filled after pumping and the vacuum had receded. Google Lavac and go to the blake web page, they show all the reccommended ways of plumbing a Lavac. I tried to get them to send me the correct vent piece but I never received a reply. Before sailing I pump the bowl dry.
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Old 08-04-2008, 15:30   #3
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Lavacs are, of course, perfect, but...

Yes, the discharge "fluid" that is in the outlet hose will flow back into the bowl, particularly when the pump valves get old.
I thought of many ways to "fix" this but they all involve compromising the "set and forget" advantage of the Lavac.

I received two anti syphon "valves". The first one worked fine, but it would have been no trouble to fit the second.

If you (very slightly) increase the size of the hole in the anti syphon valve this will decrease the amount of raw water flowing into the bowl. If you make the hole too large then just put your finger on it for a few seconds to increase the water flow.

I'd be surprised if your double clamped hose is leaking, unless the the elbow is distorting. Double clamping is good but it will put a lot of pressure on the hose and joiner.

Have you checked if the moisture is coming from some other place and migrating to where it can be felt?

If you ever have it all apart (for some other reason) I would suggest:-
*Locating the screws on the clamps at 120 or 180 degrees to each other.
*warming the hose with a heat gun just before clamping.
*don't over tighten the clamps.
*replacing the elbow
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Old 08-04-2008, 17:43   #4
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Same here

My Lavac fills 3/4 of the way when I pump out. But when I want to reduce the amount of water in the bowl - i.e. if things are going to get bumpy at sea, I leave the lid open and pump - that gets rid of the water in the bowl and does not pull any more in.

These are great heads, aren't they!

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Old 08-04-2008, 18:51   #5
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I installed a Lavac Popular last year, and put an anti-siphon valve in the fresh water loop, instead of the little Lavac valve, taht they send with the head.
However, I don't get any new water in the toilet at all. It will pump out what is in the bowl, but doesn't bring in new water, with the lid down. There is some suction, as the lids sticks down, but not for long - maybe 5-10 seconds. I assume that your lid is vacuum sealed for longer than that???

I think I may have a small airleak, where the fresh water inlet fitting scews into the back of the bowl, as it feels a bit loose. I will have to take the hose off though, in order to tighten it!
Got through last year by just bringing in buckets of water from the cockpit, to fill the bowl - had bigger problems with the boat, so never got around to fixing the airleak!

One complaint about the Popular model - the plastic clamps that hold the seat, and lid onto the bowl are cheap - and loosen easily / don't keep the seat / lid on solidly!
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Old 09-04-2008, 05:01   #6
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Should seal longer

The lavac seat should seal much longer than that. It certainly sounds like you have a leak.
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Old 09-04-2008, 09:06   #7
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Jokingly when I have guest aboard. I ask them to use our head, and not the guest head. Ours has a Lavac, and I explain it will eat a tennis shoe. While the Jabso won't even eat a ping pong ball.
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Old 12-04-2008, 13:15   #8
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Our new to us Stevens 47 has Lavac heads. They are real beasts! Ours fills about 1/2 with water after a good flush but as was mentioned I just pump the bowl empty with the lid up before going sailing and no water trickles back to the bowl.

The prior owner said they never used anything special as to toilet paper and that the heads had passed some pretty abusive stuff that guests had put into them over the years. I can see how!


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