Hot water systems?

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Denek

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Hi all
Seriously looking at purchasing a boat with a Bukh DV20 engine of 2007 vintage and it does not have a calorifier fitted. I have been told that Bukh used to make a kit for this but they are no longer available and apparently it is a difficult and expensive proposition without one.
So my question is does anyone have experience of this, have a kit kicking around that I could buy( long shot) or any other suggestions to get hot water for a shower without standing under a bucket with holes in?
I have been looking at a gas option But would welcome advice please.
 
Not sure what you mean by kit? The boats I've had simply gave a standard domestic calorifier wired in series to the fresh water cooling circuit. Maybe that's where I'm getting confused and the engine you have is raw water cooled?
 
Raw water cooled engines are perfectly capable of providing hot water but the method is a little more complicated than it is with an indirectly cooled engine. At one time there was a clever little device available specifically for Bukh engines that avoided an additional pump, but otherwise an additional electric pump will allow any RWC engine to add a calorifier. There is a page on the subject on my website.

Jaguar and Mercedes cars have such a pump that enables hot engine coolant to be circulated when the engine is not running. These often come up on Ebay. I paid £25 for mine but for some reason this one had a resistor across the + and - terminals. It works fine with this cut off.
 
vyv_cox said:
.............................................. I paid £25 for mine but for some reason this one had a resistor across the + and - terminals. It works fine with this cut off.
Click to expand...

I guess the resistor is quite a high value (some k Ohms). In that case it serves to limit sparking across the brushes of the motor or induction voltage spikes damaging other sensitive circuitry in the vehicle. Removing it will not show any immediate adverse effects but it may reduce life span of the motor or some other components.
Also, it may be for reducing interference with radio communication and without it the device may not be compliant with some rules or laws.
 
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jiris said:
I guess the resistor is quite a high value (some k Ohms). In that case it serves to limit sparking across the brushes of the motor or induction voltage spikes damaging other sensitive circuitry in the vehicle. Removing it will not show any immediate adverse effects but it may reduce life span of the motor or some other components.
Also, it may be for reducing interference with radio communication and without it the device may not be compliant with some rules or laws.
Click to expand...

When I initially connected the pump the resistor glowed red hot! I removed it immediately. That was about five years ago and it has run perfectly since.
 
Hi thanks for the replies.
The engine is raw water cooled and thanks viv I will take a look at your web site.
What would I need to search for on eBay for this pump?
I have been looking at small diesel heaters too and although quite expensive I do like the sound of them and I like the idea of not having to run the engine. The boat does have a solar panel for battery charging but I suppose you would still need to run the engine to give the batteries a top up?
Thanks again.
 
jiris said:
I guess the resistor is quite a high value (some k Ohms). In that case it serves to limit sparking across the brushes of the motor or induction voltage spikes damaging other sensitive circuitry in the vehicle. Removing it will not show any immediate adverse effects but it may reduce life span of the motor or some other components.
Also, it may be for reducing interference with radio communication and without it the device may not be compliant with some rules or laws.
Click to expand...

I'm sorry, but none of that makes any sense at all.
 
Resistance across feed terminals is used to provide a dynamic brake on the motor. If the motor has the ability to run on after power is removed it is desirable to stop the motor soonest thus limiting the generation of back emf. Also, provides a "handbrake" if the motor has a chance of being driven by other means. (water circulation?)

Think shorting terminals of your wind generator.
 
So I have decided to make an offer on the boat and work out the hot water issue later. Looks like we should be able to sort something out. Thanks for the replies
I don’t know much about electronics and so I will resist any comments about resistors ( pun intended) although it all seems very interesting.
There are quite a few mods I will need to make on the boat to make it ours if our offer is accepted so I am sure there will be more questions coming your way..
 
Denek said:
So I have decided to make an offer on the boat and work out the hot water issue later. Looks like we should be able to sort something out. Thanks for the replies
I don’t know much about electronics and so I will resist any comments about resistors ( pun intended) although it all seems very interesting.
There are quite a few mods I will need to make on the boat to make it ours if our offer is accepted so I am sure there will be more questions coming your way..
Click to expand...

The resistor discussion is very much a dead end. There are loads of different types of these pumps on Ebay and no doubt the majority don't have a resistor. Or you can even buy a new one as specified on my website.
 
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