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

[Sandyman]

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

Are you running the engine at the same revs in your berth as you do at sea ??

Im looking along the lines that the stat might not be opening unless water hot enough and hence little flow through the calorifier coil.

Just a thought.

 

[snooks]

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????

 

[snooks]

Are you running the engine at the same revs in your berth as you do at sea ??

Im looking along the lines that the stat might not be opening unless water hot enough and hence little flow through the calorifier coil.

Just a thought.

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

Which thermostat are you thinking of?

Sorry, I know nothing about the workings of a calorifier

 

[Cliveshep]

If as you say the water from engine to calorifier gets hot, does the same apply to a lesser extent to the pipe from the calorifier, indicating that the water is giving up it's heat? If the return pipe is cold I'd suspect a partial blockage somewhere or a faulty engine water pump as the water is not flowing properly.

Can't think of anything else it could be.

 

[snooks]

If as you say the water from engine to calorifier gets hot, does the same apply to a lesser extent to the pipe from the calorifier, indicating that the water is giving up it's heat? If the return pipe is cold I'd suspect a partial blockage somewhere or a faulty engine water pump as the water is not flowing properly.

Can't think of anything else it could be.

Thanks for your reply

I can't understand why when we go somewhere we get hot water, and when we're just staying on the berth we don't

 

[Cliveshep]

Perhaps your engine revs are higher, and the water pump has corroded vanes so only circulates at higher revs?

Strange though, on my boat with an old Thorneycroft T.108 diesel the water gets hot as the engine reaches operating temp on the gauge and it'll do that at a fast tick-over in around 15 minutes in Summer and around 20 in Winter.

I'd look hard at how the water circulates, could it be a partial air-lock in the pipes to and from the engine?

 

[Richard10002]

I can't understand why when we go somewhere we get hot water, and when we're just staying on the berth we don't

What could possibly be happening at sea, that isnt happening on the berth, (or vice versa)?? The boat/engine doesnt know it's not moving through the water... or does it??

Have you tried running at 4-5 knots on the key for a while - you shouldnt snap your lines, even at this, (Famous last words ). At least this would confirm/eliminate the revs as an issue.

 

[snooks]

What could possibly be happening at sea, that isnt happening on the berth, (or vice versa)?? The boat/engine doesnt know it's not moving through the water... or does it??

Have you tried running at 4-5 knots on the key for a while - you shouldnt snap your lines, even at this, (Famous last words ). At least this would confirm/eliminate the revs as an issue.

With the exception of the revs (which hasn't been a problem on any previous boat I've been on) the only difference is the motion of the boat

The only thought I had was that the warmed water wasn't moving around the tank, but I've never known this problem before which is why I'm at a loss to what is happening

 

[Bosun Higgs]

Let me guess - your Sadler has a raw water cooled engine and the calorifier is fed by a pump? On that assumption:-

Your engine thermostat opens sufficient to keep the engine at the operating temperature. If the engine is only under light load as it will be alongside the pontoon, then the engine still reaches the correct temperature but the thermostat only allows a small amount of water to pass through. It is this small flow which in turn will pass through the calorifier .

To put it another way, the amount of hot water going through the calorifier will be directly related to how far open the throttle lever is.

Its also quite possible that the pump (if you have one) has gone t*ts up - they are not designed for hot salt water

 

[PCUK]

Water should feed the calorifier from below the thermostat so that it heats at the same speed as the engine water. Thermostat should have no effect on calorifier water. Have you tried reversing the pipes to the calorifier in case they have been installed the wrong way round causing a partial airlock? If the engine is raw water cooled, is the calorifier circulation pump working?
If the return pipe is cold water is not circulating through the calorifier.

 

[Heckler]

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????

Diesel engines consume fuel according to load, heat output is derived from fuel burned, so 1500 revs with no load it uses hardly any fuel, 1500 revs under load and lots of fuel burned. Ergo, load = heat output.
For info the throttle controls revs through the governor, the governor actually opens and shuts the supply of fuel. Notice if you are cruising along and you start to climb a long swell, the engine note deepens, the revs stay the same. That is the governor reacting to the load. The "throttle" is actually "opening" and "closing" without any input from you from the "throttle lever" . It is reacting to "load" and that is why when you are motoring, you put more load on the engine, and the domestic water gets hotter more quickly
Stu

 

[vyv_cox]

Graham,
Can't remember whether your boat has the raw-water cooled Bukh 20 or something later? The calorifier for the Bukh works by circulating water from the block via an inline electric pump. The flow is partly thermo-syphon, partly pumped. Absolutely nothing to do with the thermostat. I would check that the pump is still working correctly. It may be that it has seized, which they do after a few years of use. In this case the thermo-syphon is probably sufficient under a good load and temperature differential but not at lower revs.

If the engine is fresh water cooled I would first check the calorifier hoses for any kinks or obstructions. If these are OK I would check the water pump on the engine (not the sea-water pump.) For some reason your coolant is not circulating at sufficient head to reach the calorifier.

There is one other possibility. If the hoses are connected the wrong way around on the calorifier the reversed thermo-syphon can be sufficient to stop the flow from the pump, especially at lower revs. Make sure that the hot water from the engine goes to the top connection and the return comes from the lower one. I had this wrong on my Bukh engine and was amazed to find what a difference it made.
Vyv

 

[Danny]

Is the engine cooled by heat exchanger or raw water? If the former then is the calorifier above the level of the heat exchanger? If so, it's possible that there's an air space accumulating in the heating coil in the calorifier. This trapped air may need plenty of revs to overcome it's buoyancy and push it out of the coil and back to the engine header tank. Once the air is swept out everything should work OK until the engine is stopped and the air space re-forms.

(Warning: speculative mode on...)
If you think that this might be the answer check the connections from the engine to the calorifier. Maybe there's a tiny leak when the system is cold that allows air to get into the coil while the boat's not being used (the displaced coolant will 'fall' back into the engine header tank).

 

[Richard10002]

Most of the above suggest it's a load issue, even if that is to overcome a problem with pump/circulation/connections.

Given that nothing has gone wrong whilst you are at sea, I'd probably put a few more lines out, (stern lines and backsprings), and run it at enough revs to do your cruising speed, and see what happens.

Alternatively, when untethered from the quay, dont exceed the revs to do say, 2 or 3 knots, and see what happens.

Once you've done this, if it doesnt heat at sea at low revs, or it heats alongside at high revs, it's a revs/load issue, rather than an at sea/alongside issue. If the same symptoms remain, it's not the revs/load.

Hope that makes sense??

 

[snooks]

Thanks all!

It's a refurnished raw water cooled Buhk DV20, it came with the boat (1983 Sadler 32) as did the calorifier

Sound like giving her a bit more gas in the berth would be a good start, but I was hoping I might be able to get hot water while at anchor with out ploughing the seabed

Now this might sound like a silly question, but how do I know which pipes should be going in where?

 

[NormanS]

Hot water by calorifier while underway by engine makes good sense, because it is making use of waste heat generated by the engine.
It is incredibly inefficient using the engine simply to make use only of its waste heat. Far better to use either an immersion heater in the calorifier, if you have access to shore power, or if not, boil a kettle.

As others have said, your engine cooling system doesn't know that your boat is tied to the berth, so if you really must use it to reduce the present global cooling, -- give it more revs.

 

[snooks]

It is incredibly inefficient using the engine simply to make use only of its waste heat. Far better to use either an immersion heater in the calorifier, if you have access to shore power, or if not, boil a kettle.

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.

Hot water from the taps is usually a handy bi-product

We do have and immersion heater for the calorifier, the previous owner said he never got around to fitting it....when I had a look and go at fitting it myself, I realised why...It says "do not cover" and the seat board would rest on top if it was fitted

 

[vyv_cox]

Now this might sound like a silly question, but how do I know which pipes should be going in where?

Look at http://coxengineering.co.uk/calorifiers.aspx for much of the info. In some cases the circulation pump will be fitted to the return side, rather than the supply. Hot water coming out of the top of the engine goes to the upper connection on the calorifier coil. And vice-versa.

FWIW I don't believe it to be necessary to run the engine harder to make the calorifier work if everything is correct. I had exactly the same arrangement as you, same engine and quite possibly the same calorifier. I could get hot water out of it at tick-over after about 20 minutes. Check that the engine itself gets hot after this time. If so there is something wrong in the installation.

If indeed your calorifier is the same as mine you may not be able to fit the immersion heater anyway. Mine was completely corroded up. Even after replacing the calorifier and using 'destructive' methods on the old one I still couldn't get the screwed blank to come out.

 

[status]

An electric recirculation pump has been mentioned and this was my thought as well.

Just thinking out of left field, the pump has not for some strange reason been wired to something like the instrument breaker i.e. one that would usualy be on whilst out but not while alongside. Assuming the issue is repeatable.

 

[MoodySabre]

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.