Generator overheating

[DBA Forum (B) - Dave Peck]

I have a keel cooled generator set (Northern Lights 8KW) which overheats when we're moored but Is fine when underway. I've been informed by the supplier that the keel cooling tank is too small causing the problem. Its fine when underway as there's plenty of cold water passing over the tank but when moored this isn't the case.

Obviously we will come to a time when we need to moor and still use the generator.

Can anyone suggest how I can resolve this problem, given that I can't increase the surface area of the cooling tank?

How easy is it to convert my generator to raw water cooled.

Can I connect the generator to the engine cooling system which has a much larger cooling tank, but only use it when we're moored?

[DBA Forum (B) - Colin Stone]

Post by DBA Forum (B) - Dave Peck
How easy is it to convert my generator to raw water cooled.

Probably expensive as you may well need a water/water heat exchanger to replace the keel cooler and a canal water circulation pump and possibly hull inlet and outlet. The term raw water cooled no longer means taking canal water round the engine, as used to be the case on older engines. Modern engines have the heat exchanger.

Post by DBA Forum (B) - Dave Peck
Can I connect the generator to the engine cooling system....

This should be feasible and quite simple. Would mean part draining engine keel cooling system and teeing off generator cooling pipes.
Also take generator hot out pipe via calorifier coil, if reasonably feasible, and then into engine keel cooler.

Colin Stone
KEI

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[DBA Forum (B) - Frank Kordbarlag]

Connecting to the main engine cooling system is probably the cheapest option - who needs to use the generator when the main engine is running?

If you do not want to go down this route, a box cooler is the best idea. Pushing canal water trough the generator is not a good idea at all if you want to keep that generator in one piece for long.

Frank

[DBA Forum (B) - Michel de Lange]

What about pumping water over the keel cooling box, simulating being under way. Maybe a small pump would suffice, thus keeping the genny separate from other machinery that you don't use when moored. 

Michel 

Op donderdag 21 augustus 2014 heeft DBA Forum (B) - Dave Peck <dbabarges-pvYRptiajiAdnm+***@public.gmane.org> het volgende geschreven:



I have a keel cooled generator set (Northern Lights 8KW) which overheats when we're moored but Is fine when underway. I've been informed by the supplier that the keel cooling tank is too small causing the problem. Its fine when underway as there's plenty of cold water passing over the tank but when moored this isn't the case.




 Obviously we will come to a time when we need to moor and still use the generator.



 Can anyone suggest how I can resolve this problem, given that I can't increase the surface area of the cooling tank?



 How easy is it to convert my generator to raw water cooled.



 Can I connect the generator to the engine cooling system which has a much larger cooling tank, but only use it when we're moored?

[DBA Forum (B) - Paul Hayes]

Hi Dave

Is it possible to connect the two cooling tanks in series, then circulate the cooling water though both of them. It may just be a bit of adventurous plumbing.

Just a thought.

Hope this helps

Paul Hayes

[DBA Forum (B) - Balliol Fowden]

Another case of not enough information on the set-up to allow reasoned and concise suggestions. What size is the cooling tank? Is it installed in the side or the bottom of the boat? What size is the main engine cooling tank / main engine? etc............

A properly designed raw water / heat exchanger system might allow you to make other improvements such as reducing echaust noise, but it will be expensive since you will, in addition to the points already mentioned, need a new wet exhaust system. But then the unit may be quiet enough for you already, in which case a Blokland box cooler (maintaining the existing closed circuit benefits) is likely to be the most cost effective upgrade.

What we did with success on a number of boats with slightly undersized cooling tanks was to weld fins on the outside, say strips of 50 x 10mm flat bar, to increase the wetted thermal transfer area. Or if grossly undersized, build a bigger external cooling tank........................

A simple point: how much paint is on the outside of the tank?

Subject to more detail it may be that the present tank size is marginal but that the installation could be improved without major surgery. We are not told the size but I suspect that the tank size may be marginal rather than grossly undersized if a simple bit of water flow cures the problem.

Balliol.