Calorifier conundrum

[Leighb]

A bit of a saga.
New to us Storebro 31 Biscay
Twin VP TMD40A engines
We knew some work needed as found on survey by VP of this parish.
All work down, mainly on Port engine, and all seems OK.
However as part of the refurb we had a new calorifier fitted, old one probably original, looked a bit iffy corrosion wise, and had no immersion element.
No hot water circulation from the engine through the calorifier.
Engineers have bled all air out. Still no joy, yesterday they stripped it down again and checked that coolant could flow all the way through the calorifier and back to engine, so no blockage anywhere, but still no flow when engine running.

Thermostats have been checked and operate normally, engine gets up to normal temp and stays there, altho' we have so far only used her in the river at lowish speed.

The engineer is very puzzled, wonders if the water pump may be at fault, but surely if the pump was not working the engine would overheat?

Are there known causes of some internal blockage that might cause this? Sludge or whatever perhaps?

Hoping someone may have a useful suggestion.

 

[jimmy_the_builder]

Non return valves on the calorifier coil? Have you plumbed it the wrong way round perhaps?

 

[Leighb]

Engineer checked, definitely no valves. Can't see how there could be a wrong way as both calorifier connections are at the same level?
Incidentally the unit was yard installed not DIY.

 

[jimmy_the_builder]

My point was - if the calorifier had nr valves on the coil, and you'd plumbed it the wrong way round (trying to pump against the nr valves) you'd get no flow. Do you know what model of calorifier it is?

 

[jimmy_the_builder]

Also - did the old calorfier warm up?

 

[Leighb]

Never had a chance to fins out if the old one worked, I don't recall that it was checked at the time of survey, should have done, but overlooked.
The manual is on the boat will check what model tomorrow when I go back.

 

[Seastoke]

Never had a chance to fins out if the old one worked, I don't recall that it was checked at the time of survey, should have done, but overlooked.
The manual is on the boat will check what model tomorrow when I go back.

I disconnected pipes from engine then put a long loop of clear hose on to see the flow of water worth a try

 

[Leighb]

Have now had a look at the manual. It is a Sigma Marine Boiler Termoinox BO 30 UT.

The connections are S for Cold water in, N for Hot water out, and E & W for the engine connections. There is no indication that it matters which engine connection is the input and which the output.

There can be no valves involved therefore. The obstruction has to be within the engine, either at the supply or return. Could this be due to sludge in the waterways?

Any suggestions as to how to proceed further will be gratefully received.

 

[jimmy_the_builder]

Sigmar, not Sigma, but you're right, this model doesn't have nr valves. Seastoke's suggestion is worth a go, otherwise it sounds like an engine issue as you suggest.

 

[QBhoy]

Hi
What I would look at...if it helps...
Firstly I'd take the two hoses off at the engine and blow through them, proving there is no blockage.
Secondly (or perhaps firstly, on reflection) I would be checking the hoses are installed on a positive pressure point of the cooling system...presumably they would be, if it had one fitted previously.
Thirdly, are we certain there are no N/R valves there and the hoses are the wrong way ? Easy to check, I'd imagine.
Also, presumably the engine isn't loosing coolant through into the domestic system ?
All the best.

 

[QBhoy]

Or....depending on the set up and plumbing...the thermostat isn't opening and getting coolant through the calorifier ?

 

[longjohnsilver]

I disconnected pipes from engine then put a long loop of clear hose on to see the flow of water worth a try

That's an excellent idea. And I'd get a fresh water hose and connect it to the calorifier and check that water flows through in both directions. On my engine ath the outlet there is a tap. Worth checking whether you have one, and if you do, that it's open.

Let us know once you've discovered what the problem is.

 

[Leighb]

Hi
What I would look at...if it helps...
Firstly I'd take the two hoses off at the engine and blow through them, proving there is no blockage.
Secondly (or perhaps firstly, on reflection) I would be checking the hoses are installed on a positive pressure point of the cooling system...presumably they would be, if it had one fitted previously.
Thirdly, are we certain there are no N/R valves there and the hoses are the wrong way ? Easy to check, I'd imagine.
Also, presumably the engine isn't loosing coolant through into the domestic system ?
All the best.

Thanks for your suggestions
1) already done by engineers
2) The hoses are on the original connection points - in fact they are the original hoses, so I must assume they are the correct connection points.
3) Quite certain there are no N/R valves
4) No, new calorifier, certainly no green stuff coming out of galley tap.

Sea stoke, I will see if we can try that, however because there are no stop valves on the engine connections, every time the hoses are disconnected the engine has to be drained of coolant, all 20+ litres of it, and then refilled again, which is a pain.

Long john silver, I wish there were taps would save a lot of bother!! Coolant definitely flows right through the calorifier heating circuit when both ends are disconnected from the engine, but no flow at all when engine is running.
Re Thermostats - there are 2 on the TMD40 - they have both been checked and operate correctly..

 

[Plum]

Thanks for your suggestions
1) already done by engineers
2) The hoses are on the original connection points - in fact they are the original hoses, so I must assume they are the correct connection points.
3) Quite certain there are no N/R valves
4) No, new calorifier, certainly no green stuff coming out of galley tap.

Sea stoke, I will see if we can try that, however because there are no stop valves on the engine connections, every time the hoses are disconnected the engine has to be drained of coolant, all 20+ litres of it, and then refilled again, which is a pain.

Long john silver, I wish there were taps would save a lot of bother!! Coolant definitely flows right through the calorifier heating circuit when both ends are disconnected from the engine, but no flow at all when engine is running.
Re Thermostats - there are 2 on the TMD40 - they have both been checked and operate correctly..

Aha, you have Volvo Pentas. Suggest you check all along the hoses from the engine to the calorifier. Look for an in-line cylindrical gizmo, copper colour, about the size of a tin of peas. If you find it, that may be the problem. It is a thermostat, a VP optional extra to be used in the calorifier circuit. It severely restricts water flow to the calorifier then opens fully once the water water from the engine is hot. It is designed to ensure the engine gets to full operating temperature before it starts losing heat to the calorifier. I have one and it does work but you have to wait until the engjne is fully hot before you can detect any significant flow. VP discontinued this thermostat a number of years ago. You could just get rid of it. If you do not have one, sorry have no other ideas.

Www.solocoastalsailing.co.uk

 

[longjohnsilver]

Aha, you have Volvo Pentas. Suggest you check all along the hoses from the engine to the calorifier. Look for an in-line cylindrical gizmo, copper colour, about the size of a tin of peas. If you find it, that may be the problem. It is a thermostat, a VP optional extra to be used in the calorifier circuit. It severely restricts water flow to the calorifier then opens fully once the water water from the engine is hot. It is designed to ensure the engine gets to full operating temperature before it starts losing heat to the calorifier. I have one and it does work but you have to wait until the engjne is fully hot before you can detect any significant flow. VP discontinued this thermostat a number of years ago. You could just get rid of it. If you do not have one, sorry have no other ideas.

Www.solocoastalsailing.co.uk

That's about the only a thing that makes sense of what's happening.

 

[Seastoke]

Also if you have to take off hoses fit two in line valves then you won't lose coolant again good luck ps if there is a thermostat in the pipe ,get a new engineer ?

 

[Leighb]

Plum, thanks that's interesting, will make sure we look, LongJohn, I agree, if present he should have found it, we will see!!

 

[vas]

2) The hoses are on the original connection points - in fact they are the original hoses, so I must assume they are the correct connection points.

if everything else fails and you've not got an inline thermostat, maybe worth checking with the workshop manual that these ARE the correct connection points! Maybe they were wrong and the system never performed properly... I know sounds silly but could happen!

good luck

cheers

V.

 

[Leighb]

Further update,

All above suggestions checked. No taps, no inline thermostats etc.

Coolant flows out of calorifier connections when hose removed so no internal blockage.

Today calorifier hose connection at pump removed and an 18" section of clear pipe substituted. Coolant flows into pipe up to level in header tank. However when engine started and run up there is no change in the coolant level in the pipe, so no pressure generated to create flow in the calorifier. This was tried at both connections with the same result.

Conclusion, could the coolant pump be faulty and not pumping? There is no evidence of any play in the pump bearings, nor coolant leakage from the front of the pump. Only possible cause of failure would be the impeller being detached from the shaft? In that case I would expect that the engine would overheat even at low speeds after an hour or two?

Any suggestions to solve the mystery very welcome.

 

[Trundlebug]

My experience with a horizontal calorifier is that you have to force the air out of the coil using mains pressure or a strong pump, before you connect to the cooling circuit.
The critical part is when you swap over the two, not to get any air in that could cause an air lock.

The engine water pump isn't a high pressure item, and will circulate water only if all the air has been bled out. I know you said the yard had done this, but until and unless you've witnessed it you can't be sure. Get a hose connected either to your domestic tap or a mains water tap, disconnect both ends from the calorifier and blast water through to force the air out.

I'm speaking from personal experience having had the same problem (albeit with a different engine).