Engine Raw Water syphon

cagey

cagey

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2 Questions please

1 Between which 2 points should the syphon be positioned, I have always thought between heat exchanger outlet and water injector on ex down pipe but a few people have insisted it should go immeadiately after water pump and before inlet on exhaust, where do you put yours?

2 To position syphon valve correct height above WL will involve 4 metre flow and 4 metre return with pipe dropping 600mm to bilge level then climbing 1 metre to valve.This will leave lot of water in pipe which may contribute to problem I am trying to solve.
Do you think this trapped water (albeit vented) is going to be problem

Engine is Beta 28 hp F Water cooled.

Beta were helpfull but there best advce was "It should be ok but keep an eye on it" Not really what you want to hear on a new installation.

Guidance please

Keith
 
Keith

1. I have mine installed as you describe, basically syphon piping replaces the otherwise direct connection between heat exchanger outlet and water injection at the exhaust; no problems so far

2. Are you sure you need all those lengths of tubing ? mine are about 1m from exhanger upwards to syphon valve, 1m from syphon valve downwards to exhaust water injection point...

anyway, as for water quantity, if you run the engine at idle for some time there will be very little water left running in the tubing (personally I was very surprised), so not much should remain when the engine is shut off, a normal size muffler should be able to cope imho
 
Cagey, either side of the heat exchanger is fine, it does not matter. I prefer to put them before the heat exchanger to avoid them being pressurised with exhaust gasses. There are two types of syphons, those with valves and those without. The ones without have a small (approx 1/8" dia) plastic pipe lead to a skin fitting which I think are better as they are kept clear by a constant stream of water and don't stick like the valves tend to. You will get a constant stream of water out of it but this will not affect your engines cooling and you can see that it is still working because there will be a little pee of water out of it all the time. If this stops you know it is blocked. With a valve you don't know if it is stuck or blocked and it is usually only an engine disaster that tells you. Route the plastic pipe to somewhere on your transom or near your exhaust, but not where it will pee all over peeps on any pontoon you are tied up to! Take the pipe to the highest point possible on your engines water supply to the heat exchanger which hopefully is above the WL anyway. No matter if it isn't but try not to loop down too much. Straight out or up is best but if you have to loop down to get out it will still work OK and the amount of water in the teeny pipe will never cause a problem. Remember the objective is to let air in when the engine stops to avoid the cooling engine sucking water back up the exhaust from your water trap. So long as you have a pipe to atmosphere at the highest point in your water system you can fit it you have achieved the objective.
 
Q1 Either between pump and inlet to heat exchanger or between heat exchanger outlet and inlet to exhaust would achieve the same result in breaking the syphon. Vetus catalogue shows it between outlet of heat exchanger and inlet to exhaust.

Q2 I agree with Roberto the valve needs to be a min of 400mm above the water line but should not require 4 metre s of pipe to achieve this in fact I would ensure that it did not need such a length by mounting it adjacent to the engine.
 
John, if the top of the engine is below the waterline a valve is a bad idea anyway. It is far preferable to just remove the valve itself from the vetus fitting and fit an air pipe to a skin fitting that is well above the waterline leading from it. The only thing these valves do is make it unnecessary to have a pipe lead out of the boat. They often either jam and cause complete distruction of the engine or leak water into the bilge. Why oh why don't people see the alternative is just throw the valve away and fit an air pipe lead to a skin fitting? Surely as a fellow CE you can see the logic of this?
 
I was under the impression that the need for the syphon break was to stop water being drawn through the engine and seacock (which many people tend to leave open for the duration of the voyage). If there is a possiblilty of drawing a 2" column of water up the exhaust I may have to consider fitting one. Cagey, the arrangement of flexi tube and copper plumbing between the heat exchanger and injection point, is where Beta are expecting you might want to put a break... As it was explained to me anyway.
 
So does anyone know where to get a simple stainless tee fitting that can be put into the cooling water line - preferably with jubilee clips and preferably something like 20 x 3 x 20? I've looked at the Vetus fitting but frankly £55 odd for a bit of plastic with a valve that I don't want is too much.
 
Just doing the same thing - and with a Beta 28.

I'm fitting it between the heat exchanger and exhaust injection (as in beta installation diagram).

Like you - to get a siphon break to somewhere where I can vent without needing a valve that will stick - and won't pour water into the bilges - also means running 2-3m of pipe out down, along and up before fitting a T then back again and vent to cockpit. When I described this to Beta (Neil) - they said it was fine.

Initially I was concerned about the extra volume of water held in the system - but:
1) It is only the exhaust side of the loop will drop into water into the exhaust when engine is stopped
2) If you work out the volume - its small - and of course if you have run the hose low before lifting it up again anything in the low part of the pipe will sit there - so volume added to exhaust really is tiny.
 
Don't disagree with you Mike but with either type of syphon break connection I would not locate it 4 metres away from the engine. I can't quite see that it makes a difference if the engine is below the water line as long as both the syphon loop and the exhaust outlet (or exhaust gooseneck) are the necessary 400 mm above the water line. I have a valve on my installation one of the inverted rubber boot type so a quick clean every now and then keeps it salt free.
 
Which syphon break have you gone for?

I believe the halyard one recommends less head than the Vetus ones.

Why do you have a need to have 4m pipes - is it so that you can get somewhere that is high enough? If so, and if you remain a bit closer (eg in the engine bay) then what sort of head will you have left?
 
Re: Engine Raw Water syphon: VETUS VALVE WARING!!!!!

The Vetus Anti-siphon valve did NOT work on my boat.

The problem was the spring that closes the valve was TOO STRONG for the small amount of weight presented by the water column in the hose outlet from the heat exchanger.

With the valve and spring in place this valve can easily allow water to siphon back into the engine.

After quite a bit of experimentation, I removed the spring.
This allows water to flow out of the valve when starting and at low RPM, but when the pressure increases with higher RPMs, the valve closes.

I put a through-hull in my boat above the water line and ran a tube to it to allow the water to leave the boat without hoses and things in the cockpit.

I can also tell each time I start the engine that the valve is clear because at low RPM's, the water is flowing.

Even more robust is to just remove the valve assembly completely, however, then you will have a constant stream.

I think a boat looks funny motoring down the estuary with a stream of water shootting out of the hull from the side!

Just be sure your anti-siphon valve is actually functioning. Sea water in your engine really sucks!
 
there is a vetus "copy" in the Force 4 catalogue for 15 quid.
I just bought a vetus with valve but i'm taking it back tomorrow to get my money back!
 
fwiw,

I routinely check the vetus valve I have, but until now I did not feel any need to modify or dismantle it, as soon as the engine is stopped air quickly enters the valve and water quickly flows away... in all I am satisfied /forums/images/graemlins/ooo.gif
 
I've only just completed installing a new Yanmar 3YM20 and I fitted the syphon directly after the raw water pump. To fit it in the line between the heat exchanger and the exhaust elbow was not an option because the pipe is to short.

The only difference is that I kept the same set up as on the original engine in as much as the small pipe runs up inside the engine box (approx. 400mm above water level) but then runs to the Vetus water cooled silencer.

Peter.
 
No thats right. unless the engine is 4 metres below the waterline (bit difficult) you don't need 4 metres of pipe! I took it that Cagey needed 4 metres of pipe to vent to a skin fitting on the other side of the "valve" In fact if he does so and the skin fitting is well above the WL he does not need a valve. Also as an engineer you probably inspect and maintain your valve regularly which is fine. How many people do? Out of sight-out of mind. As you have probably grasped by now I have a real problem with the vetus one in particular as it has a mechanical valve with a spring that is just asking to jam and has to be dissassembled to inspect (so people don't) Whenever I see one of these I take the valve out completely and throw it away, fitting a pipe overboard to a skin fitting instead. You can buy the plastic pipe and little skin fitting for pennies and then forget it!
 
Pray that it continues that way. The problem is that when it does jam the first indication might be a bent con rod!
 
You can buy equal tees in plastic from plumbers supplies which is fine, and reducers to 1/8" bore. The skin fittings for 1/8 pipe are available but more difficult to find.
 
Re: Engine Raw Water syphon: VETUS VALVE WARING!!!!!

Don't you already have water shooting out of your exhaust? I hope so! Site the skin fitting alongside the exhaust if you think it looks funny....
 
Hi Mike, OK - curious now - as I think people are describing 2 different setups now.

The beta manual and diagrams in Nigel Calders book etc all show the T needing to be above water level (c. 30-40cm) - but if I understand what you are saying correctly you are suggesting that the T can be below water level so long as the breather exits well above (apologies if I've got it worng)

I've struggled getting me head around this - but assumed that the diagrams were right and therefore if the T was below water level the breather tube could sit with water in it and so siphoning could still occur in some way /forums/images/graemlins/confused.gif

Are you saying that the T can be anywhere so long as the breather pipe exits AWL. That was my original logic from basic physics - but I lost confidence as all the diagrams show the T AWL

I think Cagey is trying to set it up as in the diagrams - with the T AWL - and I can see why this might be tricky to achieve neatly directly above the engine

Thanks
 
Re: Engine Raw Water syphon: VETUS VALVE WARING!!!!!

Also - according to Nigel Calder - so long as the breather exits above the highest point in the exhaust system - then you should not have water weeping out anyhow ?

I think I can see the logic in this ...
 
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