What's up with my calorifier?...UPDATE

[boatmike]

My calorifier works fine at sea, run the engine for 30 mins, nice hot water...No problem there

In my berth I run the engine under load (i.e. in gear) an 30 mins later the chill had been taken off the not "hot" water

An hour later, and the water can't even be described as tepid

But go out on the water and it's fine

Anyone have the faintest what's going on????

What is going on is very simple. You are putting the engine under load at sea, but not when not (if you see what I mean). The throttle opening will tell you a lot. Just putting in in gear and running at small throttle openings won't get the engine hot. Doing so will only cause high wear, a lot of noise, and annoy the neighbours.

 

[snooks]

If I was a boat near to you in the marina I would suggest that you fitted an immersion heater in the calorifier and switched the engine off. Or put the kettle on.

Hang on a sec I'm not running my engine at obscure times of the day and night for hot water, I'm just running for 30-40 mins at the weekend, because I believe it does the engine good to get it up to temperature and have the oil/water pumped around it every now and again.

If you were near me, and did suggest I "fitted an immersion heater in the calorifier and switched the engine off" I'd politely tell where to go I'm not being antisocial, I'm just looking after my boat. I don't mind that others run their engines, because I know they do it for the same reasons I do. In fact on Sunday two boats in the same line were doing the same thing.

How about if I use a jigsaw in the cockpit? Would you suggest I cut the wood by hand?

Marinas really aren't the place for piece and quiet, that's why I go sailing

You're more than welcome to see if you can fit the immersion heater I have, but as Vyv has said, the nut on the top is seized and will not budge, and if I did use it I'd have to remove the cushion.

But as I've already said, this isn't about me running my engine for hot water...it's about why I can't get hot water when I run the engine in the berth

 

[beneteau_305_553]

It could be the engine thermostat is faulty and the engine is just not getting up to temperature unless at high revs. The water hoses should be hand hot after just a few minutes.
I run mine for just 20 mins on slow speed to charge batteries and water is hot. ( I don't engage gear as the modern diesels dont mind running at low load.)

 

[Bosun Higgs]

When we're on the boat and not going anywhere (maintenance weekends as we call them) we run the engine to keep it in tip top condition, I don't like the thought of the engine sitting there over winter, so run it as often as we can.

Not a good idea Snooks. Not only wont your water be getting warm but its likely that you oil wont either, in which case it will accumulate water and combustion by products and do no good to the engine. Most engine wear occurs on start up anyway.

Best thing to do with the engine of a laid up boat, after changing oil etc, is to leave it to sit until the next season.

My comments about the thermostats were based on a Volvo 2003 raw water cooled where definitely the water going through the calorifier is the bleed off from the thermostat. If the Bukh definitely is different, then the likely culprit the lack of real load and possibly the pump..

 

[ianj99]

Skipper_stu has the answer in his reply. Not enough of a load means not enough waste heat.

Same reason why your diesel car will reach operating temp when driven from cold compared to sat idling in your drive.

I

 

[capsco]

Skipper_stu has the answer in his reply. Not enough of a load means not enough waste heat.

Same reason why your diesel car will reach operating temp when driven from cold compared to sat idling in your drive.

I

This is a good explanation of the problem.

 

[MoodySabre]

this isn't about me running my engine for hot water...it's about why I can't get hot water when I run the engine in the berth

My immersion heater doesn't work either so we only have hot water when the engine has been running. I wouldn't think of running the engine just for hot water - if it needs a run then I'm out of our generally quiet marina having a toodle before or after a sail. Anyway, I did digress from your question for which I apologise.

 

[snooks]

My engine gets hot, my oil gets hot, the pipe to the calorifier gets hot. The only thing that doesn't get hot is the water in the calorifier.

 

[Cliveshep]

My engine gets hot, my oil gets hot, the pipe to the calorifier gets hot. The only thing that doesn't get hot is the water in the calorifier.

Back to what I said to you before then, check pipework and if you have an electric circulating pump as some suggest check that as well. Frankly, even if you had the pipes back to front, once water flows around the internal coil it will pass that heat through the conduction of the copper coil into the water surrounding it. The fact that it does not circulate by inference suggest either a pipe blockage or defective pump. I think you've set the scene thoroughly enough to leave few alternatives. An engine at tick-over will produce enough heat to heat water as an inevitable by-product of combustion heat, that's a given. Yours gets hot, water in pipe out of calorifier does not - ergo blockage, air lock or pump m'dear!

 

[snooks]

Yours gets hot, water in pipe out of calorifier does not - ergo blockage, air lock or pump m'dear!

When I'm on the boat next I'll check

What I don't understand it why it's blocked, got and air lock or has a defective pump when she's on her berth, and doesn't at sea.

Is it possible that the motion of the boat (on and through the water) will move the air around through the system?

If so, I think everyone you've found the root of my problem

If not.....

 

[snooks]

I wouldn't think of running the engine just for hot water - if it needs a run then I'm out of our generally quiet marina having a toodle before or after a sail. Anyway, I did digress from your question for which I apologise.

No worries

Thank you for your apology. If I didn't have work to do on the boat, I'd quite happily motor around the harbour...But the job list on the boat grows with every day I work on it

 

[steve6367]

Very interesting thread - my setup Yanmar 3YM21 does exactly the same. If I motor under load the water gets hot within 20 mins. If I run when stationary it does not - I had always assumed not being brave enough to run the engine at 2500rpm in gear stationary there simply was not enough waste heat. Much like you though the pipes to and from the calorifier get hot even at tick over.

One area I may focus on is the thermostat as the engine cooling water enters the calorifier – this is according to the instruction to stop the flow once the water in the calorifier is hot and so stop if getting too hot………do you have one of these snooks?

As people seem to be saying this is not normal I will have an investigate and report back

 

[snooks]

One area I may focus on is the thermostat as the engine cooling water enters the calorifier – this is according to the instruction to stop the flow once the water in the calorifier is hot and so stop if getting too hot………do you have one of these snooks?

Oh goodie!

It could be something else, and no doubt expensive

I love boats!

 

[Ubergeekian]

If I had a rev counter I could tell you Sadly I don't, I have it in forward, but powering forward at probably around 3 knots if the ropes weren't stopping us, not the 4-5 knots I usually motor at

I know that the water (or the pipe at least) going to the calorifier from the engine, gets hot to the touch...but the caloifier doesn't get warm to the touch

I think this is a definite case for Occam's razor - keep it simple. And the simple solution is ... your system is working just fine. You know it works when you are motoring at sea, so all the pumps, thermostats, hoses, pipes and so on can do their stuff.

So why don't they? Because you are not running the engine under nearly a high enough load. The drag on a boat is pretty closely proportional to the square of the water speed, and the power is drag times speed, so proportional to the cube of speed.

If you are running the engine fast enough to give 1/2 your normal cruising speed then you're running it at about 1/8 of normal cruising power, which means 1/8 of the waste heat to dispose of. The pipe to the calorifier may get warm, but the flow rate along it is probably tiny compared to motoring at sea. Practically no heat input => practically no hot water.

Note the cubic sensitivity, by the way. If your speed would be 2/5 (2kt vs 5kt) of normal cruising then you are at 6.5% of normal cruising power.

Relax. It's all working fine!

 

[Bosun Higgs]

One area I may focus on is the thermostat as the engine cooling water enters the calorifier – this is according to the instruction to stop the flow once the water in the calorifier is hot and so stop if getting too hot………do you have one of these snooks?

This is what I suggested but I was wrong - the system on the Bukh works the other way round ie the water flow to the calorifier gets hot at the same speed as the engine and before the thermostat opens. Unlike my old Volvo and by the sound of it, the Yanmar too.

I suppose its just possible that the thermostat is jammed open so the cooling water doesnt get hot enough.

So it's simple really - you dont have enough of a flow of really hot water through the calorifier when the boat is on the pontoon but you do when it is being used for real. That can be a combination of things all of which need checking. Pump becoming inefficient / pipes part blocked / engine not hot enough.

 

[steve6367]

This is what I suggested but I was wrong - the system on the Bukh works the other way round ie the water flow to the calorifier gets hot at the same speed as the engine and before the thermostat opens. Unlike my old Volvo and by the sound of it, the Yanmar too.

I suppose its just possible that the thermostat is jammed open so the cooling water doesnt get hot enough.

So it's simple really - you dont have enough of a flow of really hot water through the calorifier when the boat is on the pontoon but you do when it is being used for real. That can be a combination of things all of which need checking. Pump becoming inefficient / pipes part blocked / engine not hot enough.

Wrong thermostat - engine is fine and on Yanmar the calorifer is not effected by engine stat. My calorifer has a seperate stat on the engine water inlet to control the temperature of the domestic water.

Steve

 

[Vara]

Another factor is at this time of year the water you are heating is much cooler than in the summer, as is the inlet cooling water, so the whole system will take longer to heat up.

 

[snooks]

Right, all the other more pressing jobs are done, and it's time to revisit this chestnut. I've run the engine at faster/cruising revs, and still no joy on the mooring. Motored back from port solent yesterday, and had hot water, motored on her berth, nothing so here are some pics

ok the pipe forward on the engine is cool, the one further away, aft, is the hot pipe

Sorry about the fuzzy photo iPhone... The top black pipe is hot, the bottom one just visible is cold (and is attached to the front of the block on the engine.

So what now? Any ideas?

Many thanks

G

 

[RAI]

I wonder if there is air in the system that gets disturbed into motion by a seaway but stays put in the berth.

 

[snooks]

I wonder if there is air in the system that gets disturbed into motion by a seaway but stays put in the berth.

An airlock has been mentioned, but I've no idea which pipe to remove and top up, at a guess the cold one, but I don't know.

Ok just taken off the cool pipe, no air lock, topped up and replaced....next?