Question re: vacuum operated heads

[suse]

Sorry - dont know the name/make, but I have inherited a loo operated by vacuum suction via the seat and lid. It appears to work - ie flushes with 10 pulls of the lever, then a five second wait, then 5/6 more pulls, and a vacuum you cant break during this time and for around 30 seconds or so after. All this according to the printed instructions still stuck to the bulkhead. When I eventually lift the lid, peering warily inside, the loo is half full of 'clean' water, previous contents having been evacuated - hooray!

The question is: should the loo have ANY water remaining? I thought the second batch of levering should have emptied the bowl. I'm not sure I want to heel over more than a few degrees with loose water, albeit clean, slopping around.

Helpful suggestion all welcomed.

 

[summerwind]

Excellent toilets. You have two pipes: The exit much larger than the inlet.

Old contents pumped out leaving pressure drop in sealed bolw. Nature abhors a vacuum so clean water enters through smaller pipe. Second pump not absolutely necessary, but makes sure that waste gets out of exit system.

If you want to empty bowl, just pump without closing seat. No pressure drop in bole so no clean water sucked in. Smple.

One trap, if you will pardon the pun, make sure that the anti-syphon hole in the top of the inlet pipe is kept clear. If not, and bowl gets below water line outside, it gets very wet inside of boat.

 

[PeteMcK]

Assuming it's a Blakes Lavac, I'd guess there's a loop of inlet hose behind and above the bowl. At the top of the loop, there should be a small plastic plug inserted into the hose. This has a needle sized hole in it to break the vaccum. If the hole is blocked, you'll end up with more water than you would otherwise - in fact, the bowl will more or less fill up. Beyond that, if your boat heels a lot and you can't allow ANY water to lie there, let the vaccuum break, lift the lid and pump the clean water out. It SHOULD have a small amount of water left, in normal use. And, as marine toilets go, it's indestructable.

 

[suse]

Gee thanks! I'll try all this. I did hear about the little hole having to be kept clear, but of course had subsequently forgotten. I would MUCH RATHER have a DRY boat down below!

 

[Strathglass]

The lavac is one of the best around. It is also very to clear a blockage as the pump is a large external one and virtually every time a blockage can be cleared without stripping.
Iain

 

[philip_stevens]

I can attest to that, as I have just (this weekend) brought the pump home with me to renew the diaphragm and valves.

I brought it home as it had broken one of the black plastic discs that are either side of the diaphragm. Not wishing to pay out £15odd for a new "lever arm and flange kit", I have made a new flange out of a piece of 5mm ABS sheet. As I made a cock of the first attempt, this will now be a back-up for the good one. It works and I have spent an hour and saved £15. PBO work.

As for blockages, I have been lucky and had none. It's been in the boat since 1984 and has only had new diaphragms and valves.

Oh, yes, don't forget to change the main outlet pipe when it gets stinky. Even proper sanitary pipe deteriorates eventually.

regards,
Philip

 

[peterb]

A minor point, but one which I have known give trouble, is that it should be possible for the seat and lid to move slightly so that the rubber seals can bed down on to the surfaces beneath them. To help in this there should be some looseness in the hinge pivots. This feels as if the pivots are wearing out, but if they're replaced without the looseness then you won't get a good seal and the system won't work.

 

[stephenk]

Like you recently acquired boat with vacuum toilet. Worked well at first but recently would not pump out (obviously bowl was full) . With trepadation dismantlled pump and fault was obviously a perished rubber valve. Easy to fix and appears a straightforward design. Does not look much to go wrong.