Cooling my engine too much?

Tim Good

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I want to add a long stainless radiator in my saloon either linked into the engine cooling circuit that goes through the hot water calorifier or add an auxillary pump to my webasto hot water heating system so that it circulates through the hot water tank and heats the cabins via seperate heat exchangers / radiators.

Both methods would allow heat whilst the engine is running via the fresh water circuit.

Could this be bad news and could i cool the engine too much?

In this case it is a Perkins 80HP M90.
 

SHUG

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Your engine generates about 60Kw and if it is 30% efficient then you may have about 40kw in waste heat. Now a lot of that is radiated from the engine block so lets guess that 20kw is available for water heating. That should be enough to heat water and run a radiator with the engine running but is that what you want to do.?
In my experience on a Seastream 43 , there was enough heat coming through the floor above the engine to keep the cabin snug when the engine was running.
If you run a radiator from the hot water tank when the engine is not running then it will cool down quite quickly.
 

NormanS

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I make use of some of the waste heat from my engine, by passing hot water through a heater matrix (from a Ford Transit), with the use of some ducting and an in-line fan, in exactly the same fashion as every car heater. The engine temperature is still determined by the thermostat, but it may very slightly reduce the domestic water temperature, because the matrix in connected into the line to the calorifier. Might be worth considering instead of a radiator.
 

Tim Good

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I make use of some of the waste heat from my engine, by passing hot water through a heater matrix (from a Ford Transit), with the use of some ducting and an in-line fan, in exactly the same fashion as every car heater. The engine temperature is still determined by the thermostat, but it may very slightly reduce the domestic water temperature, because the matrix in connected into the line to the calorifier. Might be worth considering instead of a radiator.

Yeah I have a few options but the 4 heater matrix units i have in the webasto system ar basically like car systems. The water is pumped around the boat and through the matrix units. If I put a spare in line pump I can turn it on and it will cirulated the water around the system even if the webasto is turned off. I'd then turn the fans on (controllable via each cabin) and it would basically mean heat whilst the engine is running, using the hot water tank as a head exchanger.

The other option is just to plumb in a radiator directly to the circuit from the engine going to the hot tank which has the benefit of not needed a pump or fans but it would only heat that space as opposed to all cabins if I did the above solution.

Anyway I could potentially do both as its pretty easy.

With reference to hot enough on a seastream 43 then i agree but sailing through winter and in Norway next year.. nope. I would like to get the cabin super toasty so that when we drop hook and stop the engine we've made use of the engine heat as much as possible and the Webasto will have to do less work.
 
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On my perking m30 there are two plugs on I think the fresh water pump for just this option, which I do consider at this time of year, but do nothing about it.
 

lw395

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I tried this, or something very similar.
I found there was very little useful heat when idling on the mooring, or motorsailing under light loads.
The engine only gives out much heat when it's working reasonably hard.
As I try to only motor off the mooring and through the harbour entrance, it was not a success, so I bought an Eber.
Normal motoring off and on the mooring was just enough to heat the calorifier and get the engine up to full temp.

If you use your boat differently, it might be fine.
 
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