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

[Marsupial]

a stab in the half light

Ok, so I take it that the (black) pipes you show on the engine are pointing downwards to the bilge, if that is so then the black pipe you show coming of the calorifier has an arch in it that would trap air, better if you can arrange the pipe runs so the engine as the high point in the system for both the flow and return pipes, withh no dips or rises, a gradual rise to the engine is best if that can be acheived, or horizontal if not but NOT pointing down.


There is another possibility, that the connections on the calorifier were "twisted"/"overtightened" so the coil in the calorifier "kicks up" and traps air. But before you start didturbing that I would sort out the pipe runs.

good luck

 

[ELLIS100]

I'm sorry but did you miss this?

You say you motored around the Solent and it worked fine, hot water, but stopped back in the marina, no hot water.

This explains why.

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!

 

[snooks]

I'm sorry but did you miss this?

You say you motored around the Solent and it worked fine, hot water, but stopped back in the marina, no hot water.

This explains why.

I did see it, which is why I cranked up the power in the berth.

Even motoring in the berth at what would be around 5 knots through the water the hot water doesn't live up to it's name. And this isn't a problem I've experienced with any other boat I've tried it with, which has lead me to believe there may be a problem.

A problem that may develop into something worse, so I'd rather get it sorted now when I have time and resources

 

[Marsupial]

I did see it, which is why I cranked up the power in the berth.

Even motoring in the berth at what would be around 5 knots through the water the hot water doesn't live up to it's name. And this isn't a problem I've experienced with any other boat I've tried it with, which has lead me to believe there may be a problem.

A problem that may develop into something worse, so I'd rather get it sorted now when I have time and resources

IF it works when the boat is at sea and not when its at its mooring then it must be an air lock somewhere, any other explanation defies the laws of physics. Every boat I ve had and seen before heats water happily at tickover, it just takes a little bit longer. If you cant move the pipes then cut them at their highest point and put a vent point in.

But the way this thing stops and starts is weird.

 

[BGW]

better if you can arrange the pipe runs so the engine as the high point in the system for both the flow and return pipes, withh no dips or rises, a gradual rise to the engine is best if that can be acheived, or horizontal if not but NOT pointing down.

This idea will help release any airlocks, but will create a thermo-syphon effect when the engine is not running - meaning that the hot water circuit will work 'backwards' and heat the engine.
You would need to put in non return valves if you have straight, upward runs to the engine or you will never have any hot water in the morning.

 

[vyv_cox]

I could do with some more clarification of your photos. What are the two hoses at the top in the upper photo? Are they both connected to the calorifier?

Also. Where is the circulation pump? Is it working? When my calorifier behaved in a similar way it was because the pump had seized. However, it may be that the layout is incorrect, hence my first question.

 

[Thistle]

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

Does the fact that you had to top up not indicate that there was air in the system?

Makes me wonder if fresh (ie replacement) water is getting into the hot water system from the fresh water tank(s). Where are these tanks, heightwise, in relation to the hot water tank? Does everything work as expected when the fresh water tanks are full? Does the boat have a bow-up attitude at sea which might allow water to flow to the hot tank?

 

[Strathglass]

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????

There are two things which could be giving you the problem.

Normally the problem is air in the pipes to the heating coil. The boat movement when motoring will be enough to kick-start the circulation.

You need to look at those two pipes. If any of those pipes is routed such that rised up above the engine then down again there lies the problem. You need to fit a manual bleed valve by cuting the piping at the highest point and fitting a T piece . This will enable you to remove the airblock in the heating coil path.

Also the hot outlet at the domed end of the tank should be at the top not half way down the tank. From that point upwards the tank will be trapping air. The way your tank is fitted you will be loosing some storage capacity for hot water.

It may or may not be possible for you to reposition the tank to get the outlet nearer the top. Even if you could lift the domed end higher it would help.

I normally mount calorifier tanks such that the hot water outlet is as high as possible relative to the rest of the tank. I also fit a manual bleed at the highest in the hot pipe after it leaves the tank for use during initial commisioning.

Hope those comments are of use to you.

 

[snooks]

Morning all, right, shortend both pipes, no place for an air lock to hide now except the calorifier!

still no joy

Here's a photo that shows the set up, sorry for the slanty photos last night, shot using a head torch for light and put up via my iPhone. I now have daylight!

@ vyv, no circulation pump... Could this be the problem?

So the hot water leaves the back of the block on the engine, as hot, goes to the top pipe of the calorifier, second pipe comes from the bottom of the cal and into the forward pipe at the block on top of the engine - not the engine block

tried kicking it and that hasn't worked either!

 

[vyv_cox]

@ vyv, no circulation pump... Could this be the problem?

So the hot water leaves the back of the block on the engine, as hot, goes to the top pipe of the calorifier, second pipe comes from the bottom of the cal and into the forward pipe at the block on top of the engine - not the engine block

tried kicking it and that hasn't worked either!

Yes, that's the explanation for all of your troubles. See my response on 18 January. Raw water cooled engines have no flow to drive water through the calorifier. At motoring speeds I am guessing that there is sufficient thermo-siphon action to get the water around but at lower engine speeds there isn't. You need an electric pump to circulate the water, all the details on my website.

The cold water from the calorifier would be better going to a cool place on the block. It sounds as though it currently may go to the bypass side of the thermostat, and therefore to the exhaust. Not only is this inefficient, it will cause the engine to run cold. On mine the return went to the drain plug, port aft, low on the engine. I believe that the calorifier fittings are standard parts, so worth giving the Bukh guys a call.

 

[Marsupial]

This idea will help release any airlocks, but will create a thermo-syphon effect when the engine is not running - meaning that the hot water circuit will work 'backwards' and heat the engine.
You would need to put in non return valves if you have straight, upward runs to the engine or you will never have any hot water in the morning.

Its a boat for christs sake!!!

 

[Bosun Higgs]

, second pipe comes from the bottom of the cal and into the forward pipe at the block on top of the engine - not the engine block

Dont understand this bit of the description.

Dont like to disagree with the distinguished Vyv but I reckon he is wrong. Unless your engine is really cold when running alongside the pontoon, there will be no real difference to the thermosyphon when running at sea. But with the cylinder alongside the engine, a thermosyphon is never going to work and would never be the source of your hot water when running at sea. Thermosyphons need height differences to work

What is much more likely is that you are not getting sufficient flow of nice hot water through the calorifier alongside the pontoon. In part this could be down to revs and pump speed but it will also be because the engine isnt working hard enough.

Without knowing the routing of the water flow and all alternative possibilities its not possible to say whether the situation could be corrected by changing pipe runs. But certainly I've seen lots of electric pumps used to get round this sort of problem, though I havent yet found one designed to cope with hot salt water so their life isnt usually that long.

 

[vyv_cox]

Dont understand this bit of the description.

Dont like to disagree with the distinguished Vyv but I reckon he is wrong. Unless your engine is really cold when running alongside the pontoon, there will be no real difference to the thermosyphon when running at sea. But with the cylinder alongside the engine, a thermosyphon is never going to work and would never be the source of your hot water when running at sea. Thermosyphons need height differences to work

What is much more likely is that you are not getting sufficient flow of nice hot water through the calorifier alongside the pontoon. In part this could be down to revs and pump speed but it will also be because the engine isnt working hard enough.

Without knowing the routing of the water flow and all alternative possibilities its not possible to say whether the situation could be corrected by changing pipe runs. But certainly I've seen lots of electric pumps used to get round this sort of problem, though I havent yet found one designed to cope with hot salt water so their life isnt usually that long.

My point is that it needs an electric pump. The one quoted on my website is stated to be unsuitable for salt water. Despite this Sadlers fitted them to all their raw-water cooled Bukhs as part of the calorifier installation and they lasted for years. The one originally in my boat lasted for 15 years, the replacement was about 6 years old when I changed out the engine.

I'm not sure about the thermosyphon, just trying to explain the symptoms. I suspect that the hoses are incorrectly located and that may be the real cause.

 

[RAI]

Since the difference between underway and moored is the speed of water under the boat, my guess is that the boat's speed through the water is causing an extra diferential pressure between raw water inlet and exhaust. A difference that is enough to force more hot cooling water through the calorifier when underway.

 

[snooks]

Dont understand this bit of the description.

Another pic...At home so it's a bit fancier

 

[vyv_cox]

Looks very unusual to me, the hot water supply and cooled water return both seem to go to the thermostat housing, which must be at the same pressure and therefore = no flow. Quite surprising that it works at all! Even if the additional manifold (the brass-looking one) has some sort of partition inside it it's difficult to explain, as the thermostat is above it so all is at pretty much the same temperature.

 

[snooks]

Looks very unusual to me, the hot water supply and cooled water return both seem to go to the thermostat housing, which must be at the same pressure and therefore = no flow. Quite surprising that it works at all! Even if the additional manifold (the brass-looking one) has some sort of partition inside it it's difficult to explain, as the thermostat is above it so all is at pretty much the same temperature.

It was like that when we bought it, I haven't the courage to look what's underneath the brass bit

That's why I'm trying to find out what's going on....someone must have seen something like this before...and it works when we move

 

[Bosun Higgs]

Despite this Sadlers fitted them to all their raw-water cooled Bukhs as part of the calorifier installation and they lasted for years. The one originally in my boat lasted for 15 years, the replacement was about 6 years old when I changed out the engine.

You're doing well Vyv - my pal with a Sadler 29 averages about 3 years per pump.

 

[Bosun Higgs]

Looks very unusual to me, the hot water supply and cooled water return both seem to go to the thermostat housing, which must be at the same pressure and therefore = no flow. Quite surprising that it works at all! Even if the additional manifold (the brass-looking one) has some sort of partition inside it it's difficult to explain, as the thermostat is above it so all is at pretty much the same temperature.

I suppose it depends on the internal passage ways. Could be that the flow through the calorifier only occurs as the thermostat opens and even on a steamer, as the Bukh is sometimes called, the thermostat will only open partially at light loads. The answer would be to take the thermostat housing off and look at the passageways.

But I agree with you - the easy option is a pump.

 

[Bosun Higgs]

It was like that when we bought it, I haven't the courage to look what's underneath the brass bit

That's why I'm trying to find out what's going on....someone must have seen something like this before...and it works when we move

Take it off. Have a look at it. Work out what its supposed to do. Engines are basically very simple - they have to be for the greasy fingered lad down at the local garage to be able to deal with them. And you' ll only learn by taking it to bits yourself.

Golden rules: 1/ never force anything 2/ keep a record ( digi camera) or the various stages of dissembly.

You'll soon learn to love taking things to bits!

P.S. Taking it to bits and working it out for yourself is way more reliable than reading what people type on here. How else do you end up with 250 posts of differing views on a simple "perpetual motion" machine. At a rough guess there are at least 100 of the posts which defy the laws of physics.