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Hot water from generator


fudd

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Morning. I have a 6 Kva 2 cylinder diesel generator. At the moment the coolant goes directly to its own skin tank. The pipes are 28mm. Could I divert it to my calorifier without restricting the cooling effect?  The pipes that go to the calorifier from my main engine are only 15mm. 

Thanks in advance. 

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You could, particularly if you tee the new circuit off your current 28mm circuit and fit a bypass valve between the two feed and return Tee pieces.  That way you can throttle the valve to force flow though your new but smaller bore calorifier lines whilst still being able to ensure enough flow overall.

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2 hours ago, fudd said:

Could I divert it to my calorifier without restricting the cooling effect?

 

No. 

 

The cooling power* of your skin tank will be much larger than the cooling power of the coil in a calorifier.

 

The surface area exposed to cold water of the calorifier tube will be 1 to 2 square feet probably. The surface area of your skin tank probably about 6. In addition, as the calorifier heats up the temperature gradient reduces, further reducing the cooling power of the coil in it. 

 

 

*Cooling power is a term I made up. I'm sure you know what it means!

 

 

 

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3 minutes ago, Mike the Boilerman said:

 

No. 

 

The cooling power* of your skin tank will be much larger than the cooling power of the coil in a calorifier.

 

The surface area exposed to cold water of the calorifier tube will be 1 to 2 square feet probably. The surface area of your skin tank probably about 6. In addition, as the calorifier heats up the temperature gradient reduces, further reducing the cooling power of the coil in it. 

 

 

*Cooling power is a term I made up. I'm sure you know what it means!

 

 

 

I read "as well as the skin tank" into his question as opposed to "instead of the skin tank" as you have.  That's because I don't expect anyone to be that daft, however, my second assumption only works some of the time! :D

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As MtB says the calorifier is not adequate as the only cooling for the generator. But there is no reason why you can't take some of the heat from the generator to heat the calorifier with the existing skin tank providing the bulk of the cooling. If your generator has a thermostat, then plumb the calorifier in in the same way as for your main propulsion engine.

Edited by David Mack
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4 minutes ago, David Mack said:

As MtB says the calorifier is not adequate as the only cooling for the generator. 

 

I didn't say that at all.

 

I answered the exact question the OP asked, the question I quoted!

 

The calorifier probably won't be big enough alone, but I cannot know that for a fact, other than to say once the calorifier has risen to the same temperature as the generator engine, it's cooling power will have fallen to zero. 

Edited by Mike the Boilerman
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Just fit a standard calorifier connection kit to the engine. If its still an LPWS2 the plumbing will be changed to have the flow to the skin tank from the top of the thermostat housing, and the flow to the calirifier from the top of the water cooled exhaust manifold. There is a small pipe fitted from below the thermostat to the water cooled exhaust manifold. This is how Lister plumb their marine engines, and can be applied to other engines as well. The return side simply has the return from the calorifier connected to the return from the skin tank.

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2 hours ago, Eeyore said:

Just fit a standard calorifier connection kit to the engine. If its still an LPWS2 the plumbing will be changed to have the flow to the skin tank from the top of the thermostat housing, and the flow to the calirifier from the top of the water cooled exhaust manifold. There is a small pipe fitted from below the thermostat to the water cooled exhaust manifold. This is how Lister plumb their marine engines, and can be applied to other engines as well. The return side simply has the return from the calorifier connected to the return from the skin tank.

LPWS2 is that a 6Kva generator, which the OP has?. Maybe he could simulate a marinisation kit by fitting a thermostat in the cooling pipe and teeing off from the input to go via the calorifier, with the after thermostat loop via the skin tank. Is there a spare coil in the calorifier or would some way of joining into the engine cooling circuit be needed, if so then a plate heat exchanger would be one way although this will also pass some heat to the engine block, probably not a problem.

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9 minutes ago, Detling said:

LPWS2 is that a 6Kva generator, which the OP has?. Maybe he could simulate a marinisation kit by fitting a thermostat in the cooling pipe and teeing off from the input to go via the calorifier, with the after thermostat loop via the skin tank. Is there a spare coil in the calorifier or would some way of joining into the engine cooling circuit be needed, if so then a plate heat exchanger would be one way although this will also pass some heat to the engine block, probably not a problem.

I’m assuming its still the one I had built for a previous owner; this is a mod they would have had if they kept the boat. The flow and return to the calorifier would have been through a duplex “L” ported changeover valve. This would allow a choice of flow from either main engine or generator to the calorifier coil. There would be a small amout of transfer from one cooling circuit to the other when the valve is operated, but would not affect the levels. A dual coil calorifier would of course make things a lot simpler.

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Why make this so complex? The genny already has skin tank cooling circuit with, presumably,  a thermostat to allow the engine to get up to and maintain an appropriate working temperature.  As required,  hot water from the genny is heading for the skin tank to be cooled.  Whether some of this goes through a calorifier or not on the way to the skin tank makes little difference to getting it cool enough for the return to the engine.  If the bore of the new pipework and calorifier is big enough not to restrict the flow it can go directly in series before the skin tank; if the bore of the additional circuit is restrictive, fit a 28mm bypass valve in parallel with it to share the flow.  I'd go with the latter in either case, also with stop valves on the calorifier take offs to give complete control and allow isolation. 

 

Actually, I've done something very similar to add a towel radiator in the return line of my main engine calorifier circuit.  It works perfectly, the calorifier getting the hot engine coolant first and the subsequent waste heat running back in the return line warms our towels and/or shower room when we're cruising. Any excess heat is then scrubbed through the skin tank as required.  The thermostat ensures the engine heats up as quickly as ever and maintains the same running temperature as before.

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55 minutes ago, Sea Dog said:

Why make this so complex? The genny already has skin tank cooling circuit with, presumably,  a thermostat to allow the engine to get up to and maintain an appropriate working temperature.  As required,  hot water from the genny is heading for the skin tank to be cooled.  Whether some of this goes through a calorifier or not on the way to the skin tank makes little difference to getting it cool enough for the return to the engine.  If the bore of the new pipework and calorifier is big enough not to restrict the flow it can go directly in series before the skin tank; if the bore of the additional circuit is restrictive, fit a 28mm bypass valve in parallel with it to share the flow.  I'd go with the latter in either case, also with stop valves on the calorifier take offs to give complete control and allow isolation. 

 

Actually, I've done something very similar to add a towel radiator in the return line of my main engine calorifier circuit.  It works perfectly, the calorifier getting the hot engine coolant first and the subsequent waste heat running back in the return line warms our towels and/or shower room when we're cruising. Any excess heat is then scrubbed through the skin tank as required.  The thermostat ensures the engine heats up as quickly as ever and maintains the same running temperature as before.

Isolation valves at the engine are of course concidered as “best practice”, with some manufacturers fitting them as standard from new. Absolutely no issue with your appoach, in fact I may well favour it had I not been familiar with the OPs layout. A single (valve) lever to move in order to select between two conventionally plumbed engines isn’t that complicated is it?

Edited by Eeyore
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4 hours ago, Eeyore said:

...had I not been familiar with the OPs layout. A single (valve) lever to move in order to select between two conventionally plumbed engines isn’t that complicated is it?

Fair enough. ;)

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9 hours ago, Mike the Boilerman said:

 

More like it!

I rather like "Cooling Power", but I suppose it could be misused and cause a kind of arms race with fridges.  A, A+, A++, A+++ is getting a bit silly, where's "the new 3kW Icy Blast versus the 2.5kW Arctic Tundra with turbo chill" would be a far more attractive proposition for most "What Fridge" readers.  That's probably why "Cooling Power" hasn't been allowed to catch on.

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21 hours ago, Eeyore said:

Just fit a standard calorifier connection kit to the engine. If its still an LPWS2 the plumbing will be changed to have the flow to the skin tank from the top of the thermostat housing, and the flow to the calirifier from the top of the water cooled exhaust manifold. There is a small pipe fitted from below the thermostat to the water cooled exhaust manifold. This is how Lister plumb their marine engines, and can be applied to other engines as well. The return side simply has the return from the calorifier connected to the return from the skin tank.

 

19 hours ago, Eeyore said:

I’m assuming its still the one I had built for a previous owner; this is a mod they would have had if they kept the boat. The flow and return to the calorifier would have been through a duplex “L” ported changeover valve. This would allow a choice of flow from either main engine or generator to the calorifier coil. There would be a small amout of transfer from one cooling circuit to the other when the valve is operated, but would not affect the levels. A dual coil calorifier would of course make things a lot simpler.

I’ve just checked the antifreeze in the genny and can’t tell if it’s green or blue, so I’m not sure if it’s compatible with the main engine. I think I’ll just run the immersion when the genny is running. Shame to waste the heat. 

Thanks to everyone for their advice. How you got that genny in that space in the first place beats me Steve. 

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1 hour ago, fudd said:

 

I’ve just checked the antifreeze in the genny and can’t tell if it’s green or blue, so I’m not sure if it’s compatible with the main engine. I think I’ll just run the immersion when the genny is running. Shame to waste the heat. 

Thanks to everyone for their advice. How you got that genny in that space in the first place beats me Steve. 

The HRW and LPWS engines can, as far as I know, use the same antifreeze. The corrosion inhibitors in the antifreeze dictate how often it should be changed, I think the longest interval is about 5 years? Maybe change antifreeze on both at the same time and concider the plumbing mod then. 

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Why bother?

With a 6kva genset unless you have electric heating, cooking and washing machine running at the same time you could just use an immersion heater in the tank. Much simpler.

Edited by Loddon
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