Adding a Calorifier / Hot water cylinder

SolentSnowgoose

SolentSnowgoose

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I have a Mitsubishi K4D engine which I understand is similar to the 4cylinder Vetus and the Thornycroft units. However mine was marinised by a defunct company called Herald with heat exchanger parts from Polar Marine.

I am now looking to fit a calorifier and would appreciate any input from owners of similar engines ( or Vetus/Thornycroft) about where to connect into the engine cooling system.

I had considered diverting the thermostat bypass via the calorifier but wonder if this will actually provide enough hot water to heat up the cylinder ina reasonable time.

Based on the connections on the calorifier I am considering using high pressure rated 15mm bore rubber steam hose for the connections to the engine (about 4m round trip length) but again I am concerned that the pressure drop may be too high and will restrict the flow. If so I wonder if an electric pump to help circulation would be sensible ??

Any advice appreciated
 
Firstly, lets start with the last point first [an electric pump to help circulation]?

This electric pump would have to stand up to the temperature of the hot water and have a bore/flow rate suitable to the 4 metre 15mm steam pipe. This pump would need to be absolutely 100% reliable. If it failed, what might be the conesquences to you and your boat if at sea under power near the shore and with a gale setting in and a fast falling barometer?

Secomdly - restricting the water flow through a 15mm pipe?

This would almost certainly have a detrimental effect on the direct cooling of the Mitsubishi K4D engine as only a reduced amount of water (due to the 15mm restriction) would then flow through the engine block to cool the engine, it will suffer local hot spots.

A classic case of this occured in the Mini 'A'-series engine (1959 - 1887) where number three exhaust valve burnt out due to local hot-spots and poor circulation.

Thirdly [I am considering using high pressure rated 15mm bore rubber steam hose for the connections to the engine about 4m round trip length]

This is a very great length of small bore pipe and the very high Reynolds number that this length of pipe/bore ratio will cause extreme turbulance inside the rubber pipe. You need a large bore pipe over this sort of distance so that the laminar flow is not interupted. Normal water cooling pipes from engines whether marine or road transport are usually 1½ - 2" internal diameter.

One final point, just try physically blowing down a 4 metre long empty length of 15mm rubber pipe and see how your cheeks will bulge during the effort. Water would have a far harder time being forced through this pipe.
/forums/images/graemlins/confused.gif
 
I can't comment on your particular engine type but the basics are the same.

The piping will depend on whether your system is raw water cooled or fresh water cooled.

Your engine will probably run at 80 degs C or near as damit. What you have to do is put your calorifier on the same circuit as the engine. So you need to divert your engine hot water before it exhausts to the exhaust pipe through the clarifier and then send that hot water to the exhaust.

You shouldn't need any additional pumps - what you need to do is pump the hot water from the engine - re-direct it to your calorifier circuit - and then send it back to the exhaust pipe.

To put it in a nutshell, where the hot water from the engine exhuasts into the exhaust pipe, re-divert into your calorifier then connect that pipe into your existing exhaust pipe.

Peter.
 
Lets come back to the real world....
Fresh water cooled engines do not normally require a booster pump. Tap off the inlet water from the head near the thermostat with the return flow going back to the inlet for the circulation pump.

Car heater hose is adequate for the job - no need for "steam" rated "high pressure" piping - what sort of pressure do you expect your coolant to reach? - the pressure cap will blow at somewhere arounf 15PSI or less!

Length? the hoses on my setup (5/8" ø) are 12' total (6' each way plus the calorifier coil) and no problem.

If you need a booster pump (usually only needed on raw water cooled engines) these are available from Johnson pumps and are rated for hot salt water use. As I have a raw water cooled donk-donk, the pump runs whenever the engine is on and has never let me down. If the pump should fail the only problem would be lack of hot water for SHMO to do the dishes. No damage to the engine as once the stat opens I have cooling again.

Think of a car engine and the heater - turn the heater down or off and you close a valve to stop hot water getting to the heater matrix - does the engine over heat? NO.

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"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
 
The Thorneycroft T80D uses a Mitsubishi K4 engine aned many have been fitted ito Moody yachts (mine included).
The normal installation for an M376 is to have a calorifier so there is certainly a standard fitting for this purpose. Either contact Thorneycroft or ASAP supplies as they both stock extensive spares for these engines.

Cheers
 
Absolutely right. With a raw water cooled engine, circulate water from the top of the jacket via a small electric pump through the calorifier and back to the bottom of the jacket. The standard arrangement in a Bukh powered Sadler 34 is exactly like this, with about 4 metres total of standard auto radiator hose. My pump, although only rated for fresh water, ran for 15 years whenever the engine was running. I bought a replacement from T.Norris, cost about £100.

DO NOT run the discharge water from engine to exhaust through the calorifier. This water is quite cool as it consists of water that ran through the engine and also bypass water that is at suction temperature. It will warm up eventually, like about an hour, whereas you can expect hot water at your tap in about 15 minutes using the method described above.
 
What you are suggesting is exactly what I did with my Vetus 4cyl engine except I used car heater hose. Has worked perfectly for two years.
 
[ QUOTE ]
Fresh water cooled engines do not normally require a booster pump.

[/ QUOTE ]

Maybe not a booster pump, but in the case of (my) VP2003 fresh water cooled engine, there is a belt driven freshwater circulation pump, and a engine driven saltwater pump.

My calorifier is fed via the freshwater circ pump.
 
[ QUOTE ]
[ QUOTE ]
Fresh water cooled engines do not normally require a booster pump.

[/ QUOTE ]Maybe not a booster pump, but in the case of (my) VP2003 fresh water cooled engine, there is a belt driven freshwater circulation pump, and a engine driven saltwater pump.
My calorifier is fed via the freshwater circ pump.

[/ QUOTE ]And your point is? That is the normal setup i.e using the pressure differential created by the circulation pump to circulate the coolant around the calorifier piping.
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sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
 
Re: All indirect cooled engines

There sould be no need for a booster pump on an indirect cooled engine provided one takes the calorifier feed off the block / head between the circulation pump and the thermostat and taps the return line back in between the outlet from the stat and the inlet side of the circulation pump.

Do you need a booster pump on the feed to your car heater to get it to work?.

I have run several indirect cooled engines fitted with calorifiers and never had a booster pump. I do however need one on my present raw water cooled engine as there is no circulation pump, just the raw water feed pump.
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The trouble with

fixed circulation through the calorifier, by inserting the calorifier between the thermostat and heat-exchanger of an indirect-cooled engine, is the length of time it takes for the engine water-jacket to heat up.

Many systems have an additional thermostat, allowing the engine waterjacket to heat first, then the calorifier, before finally opening onto the heat exchanger.
The plumbing is more complex though.
 
Re: The trouble with

Yes, a nice refinement but more complicated and something else to go wrong. the second stat should really open at a lower temperature then the main stat. - How many car engines are fitted with secondary stats for the heater?....... /forums/images/graemlins/confused.gif

Then again , on a boat installation you really should fit another stat in the return line or a by-pass to isolate the calorifier, to stop the calorifier overheating the fresh water - some engines can run a little hot - over 100°C - nice to boil the water in the calorifier. /forums/images/graemlins/grin.gif
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"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
 
Re: The trouble with

Even so, in 20 minutes the hot water in my galley is too hot for my hand to endure. Doesn't need to be flat out motoring, either. Just hanging about waiting for the Hellevoetsluis bridge to open is enough. Yanmar GM30F with a new calorifier about 20 litres.
 
Re: The trouble with

[ QUOTE ]
Even so, in 20 minutes the hot water in my galley is too hot for my hand to endure.

[/ QUOTE ]No, No, don't you mean "too hot for swmbo's / totty's hand to endure" /forums/images/graemlins/grin.gif I do agree with the 20 mins time scale though (or even 15) - Bukh DV 24 - raw water cooled 20litre "ish" calorifier.
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Re: The trouble with

Perhaps anybody's hand, although I agree it's more likely to be hers than mine /forums/images/graemlins/smile.gif The time for my Bukh 20 raw water cooled was probably a little faster than for the Yanmar but the ultimate temperature is higher with the Yanmar, so when we changed calorifiers after changing engines we went for one a little smaller.
 
Re: All indirect cooled engines

My Sadler has a Martek heat exchange unit.

This has a Johnson electric pump that pumps fresh water around the engine and calorifier.

The original pump was so old that the electrical connectors virtually fell apart.

When this happened, the engine overheated in minutes. Had to be towed back to the berth twice before I bit the bullet and chucked the old pump away and replaced it with another Johnson pump

The second pump had better placed electrical connectors which should last as long as the first pump (circa 26 years). ((If that was the original one))

The system heats water very quickly from the Bukh 20, but as already said, is a liability if the pump fails at a critical moment.

Not sure how to get around it, as the heat exchanger needs the water flow to work. Not really like a car at all, as that "heat exchange" unit relies on a fan or forward motion to cool the radiator.
 
Re: All indirect cooled engines

OK guys thanks for all the advice ... to summarise...

I have an indirect cooled engine and based on comments above it seems that taking the feed to the calorifier from the thermostat bypass via a 5/8 (15mm) line should work ok and will not put the engine at risk of overgeating beacuse the 'stat will open and bypass the calorifier if the engine gets too hot. also given the comments above i dont think I will use a "booster" pump to circulate the water in the engine / calorifier loop.

Anyone disagree??
 
Re: All indirect cooled engines

Interesting, but there would appear to be something amiss with your engine cooling system if when the electrical pump fails the engine overheats (assuming you have a raw water cooled engine) Not everyone has a calorifier fitted - do those engines overheat?, When the calorifier reaches max temp it no longer draws heat from the coolant therefore the coolant returns to the engine at basically the same temperature as it left - ie no real cooling effect / heat transfer. If you are relying on an electrical circulation pump to pump the coolant (fresh water) through a raw water cooled heat exchanger to provide engine cooling then I would expect failure of that pump to lead to overheating but who in their right mind would rely on an electrical circulation pump for primary engine cooling? seems very risky to me. The circulation / booster pumps I refer to are the ones used on raw water cooled engines to circulate water through the calorifier and not for engine cooling. Failure of these pumps will not cause any problem except no hot water for SMHO / Totty to do the dishes.

The analogy to a car heater is accurate as there are two exchangers - one being the radiator for engine cooling and one being the heater matrix for heating the passenger compartment, this matrix being analogous to the calorifier in a boat.
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"Artificial intelligence is no match for natural stupidity"
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Re: All indirect cooled engines

[ QUOTE ]
OK guys thanks for all the advice ... to summarise...

I have an indirect cooled engine and based on comments above it seems that taking the feed to the calorifier from the thermostat bypass via a 5/8 (15mm) line should work ok and will not put the engine at risk of overgeating beacuse the 'stat will open and bypass the calorifier if the engine gets too hot. also given the comments above i dont think I will use a "booster" pump to circulate the water in the engine / calorifier loop.

Anyone disagree??

[/ QUOTE ]Seems a fair summation for a basic workable installation /forums/images/graemlins/grin.gif
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