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  1. #1
    Join Date
    Oct 2009
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    Norwich
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    477

    Default Beta raw water inlet size

    Hi. Beta Marine used to state that a 1 inch raw water inlet was required to ensure sufficient throughput (although I know some people get away with smaller). The current manual now states that for Beta 10-38, the Seacock Inlet/Seawater Engine Pump Hose I.D minimum is 19 mm. Furthermore, the manual goes on to quote that the sea water flow should be 13 - 14 litres/minute minimum at 1,500 rpm, whereas the older manuals stated 15 L/min.

    Can anyone confirm please, has there been a fundamental/physical change to the engine/raw water pump to cause this change, or have Beta simply tempered their requirements, maybe in light of evidence in the real world?

    Many thanks.

  2. #2
    Join Date
    Dec 2008
    Location
    Sweden
    Posts
    1,543

    Default Re: Beta raw water inlet size

    Quote Originally Posted by syvictoria View Post
    Hi. Beta Marine used to state that a 1 inch raw water inlet was required to ensure sufficient throughput (although I know some people get away with smaller). The current manual now states that for Beta 10-38, the Seacock Inlet/Seawater Engine Pump Hose I.D minimum is 19 mm. Furthermore, the manual goes on to quote that the sea water flow should be 13 - 14 litres/minute minimum at 1,500 rpm, whereas the older manuals stated 15 L/min.

    Can anyone confirm please, has there been a fundamental/physical change to the engine/raw water pump to cause this change, or have Beta simply tempered their requirements, maybe in light of evidence in the real world?

    Many thanks.
    FWIW, the manual for my Beta 722 manufactured 2005 states that the inlet sea cock and pipe work 'should be 22mm ID or 3/4" minimum'.
    Since 22mm is an awkward size, I used 19mm (3/4") for the inlet and I have had no over heating problems.
    However, pipes on the engine further down stream the cooling system were 22mm, for instance the hose connecting the heat exchanger to the exhaust bend. So I had to source some 22mm ID hose, as I needed to install an anti-siphon valve here.
    When I wanted to replace the exhaust bend a few years ago, it was no longer obtainable with 22mm connection, only with 25mm (1").
    My interpretation of all this is that Beta thinks 19mm is a bit marginal and 22mm would be ideal, but because fittings for 22mm ID are rare they use a mix of 19 and 25mm.

  3. #3
    Join Date
    Oct 2009
    Location
    Norwich
    Posts
    477

    Default Re: Beta raw water inlet size

    Thanks so much for your reply BabaYaga. That was exactly our thinking when we, after much head scratching, opted for a 3/4in inlet. Our engine (and manual!) date from 2013. However, we have actually only just commissioned the engine and much to our disappointment, we are experiencing over heating issues - and we haven't even left the dock yet!

    We've installed the engine ourselves and there have been absolutely no other issues whatsoever so far. The engine starts on the button, it's not using or losing any fluids at all, and it purrs along beautifully when in neutral or in gear tied up. Initially it was overheating quite quickly (after just 10 minutes or so), but after a thorough cleaning and flushing through of the both the raw and freshwater systems, and refilling with fresh coolant (30/70 coolant to water as that's all we had available), it now runs for longer (about 20+ mins) before the dreaded alarm sounds. There was a lot of sediment in the engine and the drain tap was blocked, etc. - all the normal problems that are reported widely in these forums, and all now sorted. We've ran bucket tests from the dinghy - 14/L/min. The exhaust system is all new and has an anti-siphon loop, Vetus waterlock (upright model) and swan neck. The angles are, we think, all correct. We have no idea how to test back pressure (also mentioned in the manual). The impeller is fine. The thermostat performs as expected when bucket tested. What on earth is causing our problem? We're mystified... and infuriated! We had desperately hoped to move closer to home now that we are finally actually afloat, but it looks like we might be back on the hard at Burnham for another winter...

    I haven't yet contacted Beta. I'm not sure that they'll want to offer too much support this far down the line... and I can't say that I'd blame them.

  4. #4
    Join Date
    Dec 2008
    Location
    Sweden
    Posts
    1,543

    Default Re: Beta raw water inlet size

    Since I have had none, my experience of over heating problems is very limited.
    But from your description, measuring 14 l/min in the bucket, I would forget the sea water side and concentrate on fresh water circuit – still sediment, air locks ? etc
    Or possibly, faulty alarm?

  5. #5
    Join Date
    Oct 2009
    Location
    Norwich
    Posts
    477

    Default Re: Beta raw water inlet size

    As a further test, we've just ran the bucket test from buckets (if that makes sense!), thereby ruling out the thru hull and water strainer parts of the equation, and we get the same throughput. That's something of a relief. The water inlet hose is 19mm ID and the anti-syphon loop/vent uses 25mm ID hose.

    We don't think we have any air locks. We did have initially, but we have since learnt about the bleed screw in the thermostat housing and on refilling the freshwater side we ensured that the thermostat housing was full (that's our highest point) and we have since bled the system from the bleed screw a couple of times. There is no coolant being expelled when overheating which suggested that there are no hot spots/airlocks in the system I believe?

    Faulty alarm... I don't know. The thermostat housing is showing an external temp of about 100 degrees C when the alarm sounds.
    Last edited by syvictoria; 05-09-19 at 11:01. Reason: Added more info

  6. #6
    Join Date
    Oct 2009
    Location
    Norwich
    Posts
    477

    Default Re: Beta raw water inlet size

    Having just looked again at our exhaust system, we are now wondering whether the cause of the problem may be the Marelon valve that we have on the exhaust thru hull. The valve was an impromptu purchase at a boat jumble and it has right angle hose tail connection. Could this be causing a back pressure problem? Otherwise, the exhaust system is all straight with one large loop (swan neck) just before it joins the valve.

  7. #7
    Join Date
    Feb 2006
    Location
    N Kent Coast
    Posts
    4,168

    Default Re: Beta raw water inlet size

    Quote Originally Posted by syvictoria View Post
    The thermostat performs as expected when bucket tested.
    Can you explain this?

    Also, when under load, what max rpm are you getting?

  8. #8
    Join Date
    Oct 2009
    Location
    Norwich
    Posts
    477

    Default Re: Beta raw water inlet size

    Quote Originally Posted by Pye_End View Post
    Can you explain this?

    Also, when under load, what max rpm are you getting?
    Hi. We tested the thermostat in a bucket of warm water several times, adding hot until it opened at, or very shortly after, the marked temp of 71 degrees C. I believe this proves that it's functioning correctly? It was definitely fully open by 80 degrees C.

    Since we've ran all tests whilst moored up, we haven't yet experienced anything close to full rpm! Mostly we've been running at 1,200-1,500 rpm.

  9. #9
    Join Date
    Dec 2008
    Location
    Sweden
    Posts
    1,543

    Default Re: Beta raw water inlet size

    Have you had the heat exchanger tube stack out for a check?

  10. #10
    Join Date
    Oct 2009
    Location
    Norwich
    Posts
    477

    Default Re: Beta raw water inlet size

    Quote Originally Posted by BabaYaga View Post
    Have you had the heat exchanger tube stack out for a check?
    Yes, all cleaned. New O-rings fitted.

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