Blakes Lavac, bowl always full of sea water on return to boat...

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fredrussell

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...Is this normal? I flush as previous owner instructed me, which is:

seacocks open,
close lid,
pump lever till vacuum formed,
10 more pumps,
wait for vacuum to go
lift lid and pump until bowl empty
close seacocks

Always when I get onto boat after any time at all the bowl is half full of sea water. Is this just how these heads are?
 
I have two on board and both behave the same i.e. they can be pumped near dry, go away, when I come back a small amount is in the bottom of the bowl, nowhere near full, just what really runs back from the pump. They stay empty when I am away from the boat, seacocks open or closed. Perhaps it is syphoning back after you pump it out, overhaul seacocks and pump.
 
sailorman said:
check the vacuum break vent in the inlet hose
Click to expand...

Yes, I had forgotten about this, if this is blocked can cause syphoning exactly like the OP says: -

http://www.lavac.com/images/pumps_files/Popular-Zenith.pdf

3. AIR BLEED VALVE
A simple plastic plug with a hole drilled into it. The plug allows air into the system, preventing siphon- ing and releasing the vacuum when pumping stops. The size of the hole in this valve controls the level of water remaining in the bowl. Two valves with different sized holes are provided (Spares No. TLZ9251 – the larger the hole, the less water remains in the bowl.
Click to expand...
 
fredrussell said:
...Is this normal? I flush as previous owner instructed me, which is:

seacocks open,
close lid,
pump lever till vacuum formed,
10 more pumps,
wait for vacuum to go
lift lid and pump until bowl empty
close seacocks

Always when I get onto boat after any time at all the bowl is half full of sea water. Is this just how these heads are?
Click to expand...

There should be a blead valve in the water intake at the top of the loop. If you loo is near or below the waterline it is essentially that this works as it breaks the vacuum and consequent siphoning of seawater in to the loo.

Alternatively the return valve ion the lavac is dicky and the contents of the pipe are running back in to the loo.

10 Pumps? Is that enough? You need to expel ALL the efluent from the pipe so work out (from the lavac manual) how much water is pumped and then calculate how much is needed to make sure the pipe is fully flushed.

On my loo I do 30 pumps. This insures that no calcite builds up in the pipe (Urine and seawater cause calcite to be deposited) and ultimately block the pipe. My pipes after 10 years are clean - and that's in the med where the warmer water increases the deposits.
 
fredrussell said:
...Is this normal? I flush as previous owner instructed me, which is:

seacocks open,
close lid,
pump lever till vacuum formed,
10 more pumps,
wait for vacuum to go
lift lid and pump until bowl empty
close seacocks

Always when I get onto boat after any time at all the bowl is half full of sea water. Is this just how these heads are?
Click to expand...

If the Lavac is correctly installed withe loops in both the inlet and discharge pipes and a pin hole air vent in the inlet pipe at the top of inlet loop It will not fill with water even if the seacocks are left open (We never ever closed the seacocks on the boat I crewed). See page 15 of the manual

Check the pin hole air vent in the inlet pipe. If its clear and the correct size you wont have to wait long for the vacuum to go and only a small amount of water will be left in the bowl. ( just the right amount for the next person to do a no 2)

I'd guess your inlet seacock also requires attention . Maybe the pump and the outet seacock too.

Installation and instruction manual. http://www.blakes-lavac-taylors.co.uk/pdf/lavac.pdf
 
VicS said:
If the Lavac is correctly installed withe loops in both the inlet and discharge pipes and a pin hole air vent in the inlet pipe at the top of inlet loop It will not fill with water even if the seacocks are left open (We never ever closed the seacocks on the boat I crewed). See page 15 of the manual

Check the pin hole air vent in the inlet pipe. If its clear and the correct size you wont have to wait long for the vacuum to go and only a small amount of water will be left in the bowl. ( just the right amount for the next person to do a no 2)

I'd guess your inlet seacock also requires attention . Maybe the pump and the outet seacock too.

Installation and instruction manual. http://www.blakes-lavac-taylors.co.uk/pdf/lavac.pdf
Click to expand...
Now Vic why would one have a vent hole in the discharge pipe that is under pressure
 
page 15


http://www.blakes-lavac-taylors.co.uk/pdf/lavac.pdf


3. AIR BLEED VALVEA simple plastic plug with a holedrilled into it. The plug allows airinto the system, preventing siphoningand releasing the vacuum whenpumping stops. The size of the holein this valve controls the level ofwater remaining in the bowl. Twovalves with different sized holes areprovided (Spares No. TLZ9251 –the larger the hole, the less waterremains in the bowl.
 
sailorman said:
Now Vic why would one have a vent hole in the discharge pipe that is under pressure
Click to expand...

One doesn't ........... It's in the inlet pipe

If you fit it in the discharge pipe .... its been done............. it sprays effluent all over you!
 
Stops water (or anything else) flowing back from the pipe once pumped out

They are describing it as the outlet valve in the install instructions...if it gets any amount of limescale in it, it wont close properly and water flows back into the bowl - worked for me anyway!!!
 
Last edited:
John 32i said:
Stops water (or anything else) flowing back from the pipe once pumped out

They are describing it as the outlet valve in the install instructions...if it gets any amount of limescale in it, it wont close properly and water flows back into the bowl - worked for me anyway!!!
Click to expand...

Did you mange to buy it on its own? I can only see them as part of a £60 + service kit .... £60 that cant be right
 
Last edited:
John 32i said:
I got one from my local chandlery for about £7...must be available on line
Click to expand...

Remove the valve and give it a bash or two, then put it in a bowl of vinegar to"dissolve the crud deposits and then finally put some cooking oil on it and replace- cost of your own time.
 
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