blake toilet vent

could you expand on this a bit? do you mean the water comes in but isn't pumped out? what lid do you plan on drilling? you don't mean a blakes lavac do you?
 
My experience of Blakes Lavacs is that you always have to allow the vaccum to go, lift the lid, and then pump them dry after use. No matter what the instuctions say, I've used a few on a few different boats and its always the same.

So my advice would be please don't drill a hole in the lid to try and regulate the way it sucks water in....

By the way, I also can't work out why they are so expensive!!
 
Hi Simon,

You must not drill a hole in the lid!! /forums/images/graemlins/frown.gif The design requires a tiny vent in the inlet pipe via a little plastic insert which is a press fit into the pipe. Two inserts are provided with a new unit with a slightly different size hole in each. You select the one that gives you the desired amount of water to be left in the bowl after pumping. More water with the small hole - less with the large. With no hole to release the suction pressure, the bowl will continue filling until the pressure equalises, which is why your bowl ends up full.

I strongly suggest you provide a loop (it need only be small) and position the insert right at the top. This will solve your problem without the need to drill holes in a lid that I believe is around £80.00 to replace!! /forums/images/graemlins/shocked.gif

Hope this helps

Cheers Jerry
 
By the way, I also can\'t work out why they are so expensive!!

There is one reason 'MARINE'

Unfortunately they are for a limited market and they happen to be quite good.

Another part of 'RIP OFF BRITAIN'

BTW my 1K posting.

Iain
 
/forums/images/graemlins/confused.gif With a pump in good order and the correct size vent hole in the inlet and not blocked by salt deposits the Lavac performs perfectly if the instructions are followed. At least that's my experience. /forums/images/graemlins/smile.gif

/forums/images/graemlins/ooo.gif I would have thought it important that both inlet and outlet pipes rise to point where they are above the water level at all angles of heel. The little air bleed then fits into the inlet pipe at its highest point. Check it regularly and clear salt deposits when necessary.

If you do find to much water is still left in the bowl wait until the lid can be lifted (don't force it up or you'll pull the seal off) and pump a little out or very cautiously enlarge the hole.
 
Simon,

I strongly suspect that if you do drill a hole in the lid, you will run a very high risk of inducing a crack across it. The pressures the lid takes when the vacuum is formed beneath it during the suction process (pumping) is very high, and as I have actually seen one split (and no, there was no hole in the lid at the time!) and watched the sad owner fork out a huge sum for a new one, I wouldn't contemplate risking it. /forums/images/graemlins/frown.gif

The other factor to consider is just how big a hole do you anticipate will be needed? Those in the little plastic air bleeds are tiny, certainly smaller than any normal drill bit. You must have an inlet pipe and, as long as that is ALWAYS above the waterline, I don't understand why you can't insert the air bleed into this at it's highest point, even if this is immediately before it clamps to the bowl. /forums/images/graemlins/confused.gif

BTW, I agree with iainsimpson, Lavacs are expensive, but given the superb performance (over 21 years in my case) this is one 'marine' item I think is undoubtably worth the money!! /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

Cheers Jerry
 
Hi Jerry,

i like the points you raise, the lid might indeed crack, didn't think of that.

the hole sugested by blake in the pipe is indeed v small, might be best to fit it just befer the inlet to the toilet.

that will be well above the water line, just seems perverse to make a hole in a perfectly good bit of tubing, but i understand the reasoning. also it's cheaper to replace the inlet tube.

regards,

Simon
 
You hadn't said 'Cat' before and your profile is totally silent on such matters.

Actually now more clearly explained the idea of a small hole in the lid sounds quite a good one. It would have to be very small as hole in the one in the inlet pipe is little more than a pin hole. If, like me, you are lucky enough to have some very small drills do it. My smallest is 1/32" then above that I have some small numbered drills (60, 59 & 58).

A carefully made hole in the lid should not weaken it in fact maybe you could fit one of the little bleed holes in.
 
[ QUOTE ]

A carefully made hole in the lid should not weaken it in fact maybe you could fit one of the little bleed holes in.

[/ QUOTE ]

Please Please no hole in the lid. It will immediately stop a perfect toilet working. If there is only the slightest opening in the seal, the toilet does no longer make the vacuum required to suck in flushing water.... So follow the advice given by several readers providing a vent in the inlet loop.

You really need the vacuum, but the vent breaks it down after the toilet is flushed .


Also, as said by others, never force the lid open. It might not just cause the seal to come off, it will certainly crack the lid after which the loo stops working and a new (and VERY) expensivr lid is needed.

I am very happy with Lavac's performance. Have used them sind 12 years now. better than any other marine loo.

cheers
 
Simon,

Yes, I did wonder before posting; I think that the small pipe being full of water whilst the bowl vacuum is being formed prevents air being ingested by the system; if you have a hole in the cover then as you pump the bowl empty air will enter, without much restriction, into the bowl. Will be interested in your experiment. I did not realize you had a Lavac working with a hole in the cover, does it really work well?
 
I say there would be no difference between a hole on the inlet pipe and and an identically sized hole in the lid. If the hole size is the same the same volume of air would be drawn in.

In a "normal" installation where the toilet is close to the waterline or below and the pipes rise in a loop above the toilet the air vent also breaks the syphon in the inlet pipe otherwise water would continue to syphon in until the level in the bowl was the same as the level outside, a bit of a problem if the top of the bowl is below that.

I suppose you could stop it by closing the seacocks promptly every time, but what a fag and a bit of a disaster when someone forgets. (I don't however recommend doing as has been done on the boat I crew: they havn't been shut for nearly 30 years and of course now can't be shut!)
 
Cautionary tale

[ QUOTE ]
(I don't however recommend doing as has been done on the boat I crew: they havn't been shut for nearly 30 years and of course now can't be shut!)

[/ QUOTE ]

A boat I know of set out for a voyage from Hamble to Gibraltar. Halfway across the Bay of Biscay the heads outlet pipe became blocked. Someone tried to clear the blockage by poking it with a straightened wire coat hanger, which, of course, perforated the pipe. Water started to come in, so they tried to close the seacock. Like yours, it was stuck.

Someone then had the bright idea of using a piece of tube to extend the seacock handle to increase the leverage: "That ought to move it." It did. The bolts holding it in place sheared and "it cum away in me 'and, sir!" Leaving behind an inch and a half hole through which was coming large amounts of the Bay of Biscay.

Aided by softwood plugs and a 'bucket and chucket' system, they made it to northern Spain, where they were able to replace the seacock. Ever since then, it has been religiously operated at least once every week, as have all the other seacocks on the boat.

Incidentally, the initial blockage was due to scale broken away from the inside of the pipe. We are told that this comes from an interaction between salt water and urine, and that the deposit is due to the head not being pumped sufficiently for the contents to clear the pipe. On our boat, we've measured the volume moved by one stroke of the pump, and calculated the volume of the outlet pipe, which comes to the equivalent of ten pumps. So we give it 20, to make sure.

Returning to the question of Lavac loos, a point to watch for is that the seat hinge should be slack. There should be sufficient clearance for the seat seal to fit flat down on to the bowl, and for the seal to be squeezed by the vacuum.
 
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