Why is it not possible to...

RickMoss

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... fit a calorifier to a Bukh DV10?

I asked Bukh UK if it was possible, but was told that it was not. As my old man's boat fitted with a DV20 has a calorifier, and his engine appears to be pretty similar to my DV10 (aside from the extra cyclinder), I was wondering if anybody can tell me why?

I don't disbelieve Bukh, just curious to know why!
 

Norman_E

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Possibly the smaller engine has insufficient waste heat to make a calorifier effective, unless it was a very small one. In a very small engine a calorifier could also result in the engine coolant being kept at too low a temperature for quite a while untill the calorifier is fully heated. All engines are less efficient, and may suffer increased wear until they are at full working temperature.
 

RickMoss

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Could be I suppose, but I thought that the thermostat recycled the same water until the temperature was sufficient to open it, or does it sit on the same water until the termperature is high enough?

The boat really isn't big enough or equipped to fit a shower (Sadler 26), so I guess I may have to keep boiling the kettle for hot water.
 

David2452

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There is no reason why not, the problem arises when people just cut a loop into an existing hose. It just has to be done correctly, what is needed is a thermostatic valve controling a bypass circuit to the calorifier or a therostatic valve at the take off point

The take off should be as far back and high as possible and the return should be at the suction side of the coolant pump. This should be entirely independant of the existing cooling circuit

This ensures that the calorifier has no circulation until after the engine has reached full working temp, after this there should be more than enough waste heat from even the smallest motor provided it is "on load"

David
 

RickMoss

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Thanks David. I don't suppose you know where it might be possible to buy a kit to do the job, or is it something that I would have to cobble together myself?
 

Rich_F

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[ QUOTE ]
I thought that the thermostat recycled the same water until the temperature was sufficient to open it

[/ QUOTE ]
I used to think this too. However, on my engine (Penta 2002) the deal is that some of the water always goes through (at least part of) the engine, and out to the exhaust elbow (which is why you always have water in the exhaust). When the thermostat opens, an additional flow of water is enabled.
 

David2452

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You will need to make your own, I guess you could buy one of the kits from Eberspacher designed for use with Hydronic but that really hurts the wallet.

I noticed on ebay some small calorifiers with a thermo valve already fitted in the coolant inlet, so if you can get one of those you will just need a couple of reducing T pieces so you can make the bypass for the calorifier (the bypass should be 1/2 the size of the main circuit or more scientificaly you can use the same bore and a thermostat which CLOSES at running temp in the bypass circuit.

David
 

jerryat

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Hi,

I believe it's more difficult than David makes out. I had a Bukh 10 a few years ago, and went through the same considerations as you. At the time Bukh said it couldn't be done, and they were correct. IIRC, the main problem was either the absence of a proper 'return point' for the calorifier circuit which, on my currrent 20hp Bukh is on the side of the block, or a similar problem with the 'input' to the calorifier from the exhaust manifold which didn't exist on the '10'. It DOES on the '20'.

Some people (me included!) tried taking the flow from an 'extension' on the thermostat housing, but it caused all sorts of problems with the 'stat itself and the proper cooling of the motor.

It's a hell of a long time ago, so check if these two points ARE available (things MAY have changed!) and if so, I don't see why it won't work. That said, I have the very highest respect for Norman Griffiths and Al Pearson at Bukh, and it's unlikely they're wrong on this one - it's one of the commonest questions!!!

Cheers Jerry
 

RickMoss

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Hmmmm... that reintroduces doubt again! I think that perhaps it's best to accept that water is heated in the kettle until I buy a bigger boat or fit a different engine!
 

Phoenix of Hamble

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Or, if you use shore power, fit an insulated tank with an immersion heater, which will heat water sufficent for a day sail, and keep it hot for hours..... and then you'll only have to boil a kettle if you are not near shore power for any length of time....

This is the strategy I probably am going to employ.... although I admit that I haven't asked the question yet ref my engine (an Albin AD2)
 

David2452

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You are quite correct, my reply was of a general nature not engine specific and does say that the heating circuit sould be independant of the cooling circuit on an engine of ths size. If there is no facility (eg a blanking plug on the coolant pump suction side) to fit a return hose tail then it will not be possible to do the job correctly. And if it can't be done corretly it should not be done.

So if you want hot water the only viable solution would cost around 600.00, but would also give you a heating facility.

David
 

Colvic Watson

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What about a 1KW immersion heater running from an inverter? It would only work when the engine was on of course, but then that's true for a calorifier.
 

RickMoss

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A 1kw heater would surely pull nearly 100A from the batteries... A bit excessive for my meager resources I think. The eberspacher route is probably the only sensible way of doing it I guess.

Thanks all
 
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