Calorifier / Engine Heating Up.

[ExSurveyor]

Any thoughts please.

The calorifier is linked to the engine by flow and return pipes.

The calorifier has an immersion heater fitted.

The engine is never used to heat water as it is plugged in to shore power for most of our stay and the immersion is used.

On our last visit we did have a run out for a pump out and the engine overheated very quickly, I suspect the impeller has failed as we had a loss of water out put from the rear.

The next day I noticed the engine was quite hot and assume it is transferring from the calorifier.

Should I,

Leave it as it is as it isn't a problem, apart from wasted heat under the berth.

Reconnect the flow and return pipes to the engine to reinstate the loop.

Leave the existing set up but fit isolator valves in the flow and return to isolate the calorifier when the engine is not required to heat the water.

We will be onboard for at least two weeks a month from now on but still mostly on shore power.

Thanks.

 

 

[Vaughan]

One thing is clear :

If the engine is overheating and there is a reduced flow of raw water from the exhaust, that problem is separate from the calorifier.  Possibly a blocked weed filter or, as you say, a failed pump impellor.  In that case don't forget to clear out the bits from the old impellor, which will probably be blocking the pipe leading to the heat exchanger!

As to the engine staying hot with the immersion on, I have never heard of that one before!  I suppose it is possible, by the simple principle of convection. I assume you are only using the immersion when needed and not leaving it on for long periods?

[grendel]

my thoughts are to fix the impellor / overheating problem, and treat the engine warming from the calorifer as a bonus, if  you leave the immersion on frost guard setting, it should stop the engine freezing too.

[Cheesey69]

As above, raw water cooling separate from your hot water heating. 

The heating loop will convey heat from the hot water back to engine as it’s on the same primary circuit before the thermostat 

Your impeller dies then you really need to inspect your heat exchanger if you can’t account for any bits that are not in pump housing. 

I consider the impeller as a service item and it gets changed every year
 

[floydraser]

This is the kind of stupid thing I would be likely to do: As I hardly ever run my engine I would probably suffer brain-fade and forget to open the raw water inlet valve...... 

But that's just me.

[Cheesey69]

Been there done that. 
so I stuck a micro switch on the lever and a red led on the dash. 
But what people don’t realise is that your exhaust is made out of rubber and that too melted. 
I also bought a cheap aquarium alarm that was set for 65 as 70 was melting point for my water lock. 
But above all, I do a visual. 

[ExSurveyor]

3 hours ago, floydraser said:

This is the kind of stupid thing I would be likely to do: As I hardly ever run my engine I would probably suffer brain-fade and forget to open the raw water inlet valve...... 

But that's just me.

No it was open as we started off with flow,

It was while opening up the engine area i discovered the waste of heat.

The impeller was changed in December last year but with lockdown has not been used until just recently.

[annv]

Hi If you over heated the engine you may well have cooked the engine thermostat, they are designed to fail open this will allow water flow through the engine which would normally be blocked by closed thermostat from califoria, on my last boat i had flow from calaforia to engines when using immersion heater does no harm apart from using/wasting electric you will be able to keep engines warm and able to start engines easier/with out using heater plugs, and if thermostat is faulty when replaced will stop thermo sysfone action. John

[Vaughan]

21 minutes ago, annv said:

Hi If you over heated the engine you may well have cooked the engine thermostat, they are designed to fail open this will allow water flow through the engine which would normally be blocked by closed thermostat from califoria, on my last boat i had flow from calaforia to engines when using immersion heater does no harm apart from using/wasting electric you will be able to keep engines warm and able to start engines easier/with out using heater plugs, and if thermostat is faulty when replaced will stop thermo sysfone action. John

Sounds good to me!

[annv]

Why not get a exhaust alarm this is a little metal strip that is fitted under the rubber hose connection to exhaust just after water inlet this is then wired to alarm on dash as soon as any  reduced water flow is detected causing a rise in temperature it triggers a alarm warning you well before the engine temperature rises, a must have in my opinion on any sea water cooled engines, lots of advanced warning before any damage is caused also allows you to moter and get a mooring to clear/repair the cause, engine temperature gauge useully is noticed to late to prevent damaged. John