vic008
Well-Known Member
Am installing a new engine cooling water trap. Should I have it above or below the water line. Would it have any bearing on the dread syphoning?
Watertrap at WL?
- Thread starter vic008
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macd
Well-Known Member
Water-traps are usually fitted below the water line, because that's the most convenient place to fit them and because engine installation instructions usually specify a hose length below the exhaust mixing point. The purpose of the trap is to hold cooling water settling from the exhaust, not as a reservoir for siphoned water. Siphoning, once initiated, can of course continue indefinitely.
Fitting a siphon break (in the inlet water plumbing) is something of a separate issue - although without it the trap and exhaust hoses can fill and then back-fill the engine. I suggest you check out the Vetus web site which has comprehensive instructions on exhaust design and layout. It will also guide on the size of trap you'll need.
Fitting a siphon break (in the inlet water plumbing) is something of a separate issue - although without it the trap and exhaust hoses can fill and then back-fill the engine. I suggest you check out the Vetus web site which has comprehensive instructions on exhaust design and layout. It will also guide on the size of trap you'll need.
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duncan99210
Well-Known Member
The Vetus catalogue has a set of “how to” drawings on the topic (page 82/83 here http://viewer.zmags.com/publication/d5cab42f#/d5cab42f/83). Both examples show the water trap below the waterline; Vetus are mainly concerned about how high above the waterline the exhaust water injection point is rather than the location of the water trap.
VicS
Well-Known Member
The water trap must be the lowest point in the exhuast system with a minimum hose length of 30cm between it and the exhaust outlet from the engine but it need not necessarily be below the WL
It must be capable of holding all the water remaining in the system when the engine is stopped.
The above link to the Vetus catalogue gives guidance on position and calculation of the size required. ( Also as a pdf version here http://pdf.nauticexpo.com/pdf/vetus/vetus-catalogue-2017-2018/21508-99645-_30.html )
The muffler shown in the Vetus diagrams is not normally needed with small auxiliary yacht engines
The antisyphon valve is a separate issue. Guidance on need, positioning and type of antisyphon valve is given in the same link and also, with more explanation, a few pages further on.
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ghostlymoron
Well-Known Member
Although the vetus recommendations don't specifically say 'below the waterline" it's hard to envisage (envision for American speakers) an arrangement where it could be above.
davidmh
Well-Known Member
The Vetus drawing seems to show that the watertrap should be 300mm vertically below the exhaust outlet rather that a 300mm hose length. Where would you measure the exhaust exit, at the bottom of the elbow, the top of the elbow or the water injection point.
sorry to hijack the thread with my own question but it may be of help to the OP
Regards
David H
sorry to hijack the thread with my own question but it may be of help to the OP
Regards
David H
VicS
Well-Known Member
vic008
Well-Known Member
Sorry my bad. Meant water filter to clean salt water on its way to impellor pump
VicS
Well-Known Member
In which case you will find the relevant advice is also in the Vetus catalogue, 15cm above the WL for plastic bodied strainers. Metal bodied strainers such as their type CWS and the traditional type mounted directly on to a the inlet valve can be mounted blow the WL
See
http://viewer.zmags.com/publication/d5cab42f#/d5cab42f/50
It is a good idea to mount the strainer vertically above the inlet valve to that the inlet can be "rodded" through to clear blockages
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