mick54321
New Member
Can i connect the raw water outlet to a calorifier or do i need to convert engine to fresh water cooled and use a heat exchanger?
raw water through calorifier or not?
- Thread starter mick54321
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rogerdog
Well-Known Member
simple answer is yes - need to convert as the temperature of the raw water output will probably be too low for effective operation not to mention corrosion /sludge etc problems
alan_d
Well-Known Member
You certainly can use a calorifier on raw-water cooled engines but you are likely to have to include an electric pump in the circuit. I have just such an arrangement with my Bukh DV 20.
People will be able to give potentially more helpful responses if you provide more details. Which engine are you thinking about?
People will be able to give potentially more helpful responses if you provide more details. Which engine are you thinking about?
PembrokeshirePromise
Well-Known Member
I used to have this on an MD11C raw water cooled for years - no real problems - no pump - very simple
The water didin't get as hot as it does now with a fresh water cooled system - but 50-60 C was hot enough to do washing up with !
The water didin't get as hot as it does now with a fresh water cooled system - but 50-60 C was hot enough to do washing up with !
mick54321
New Member
the engine is a yanmar 2gm
VicS
Well-Known Member
Just some general thoughts as I don't know what would be involved with that engine.
As already said the water temperature would be lower than with a fresh water cooled engine.
I don't see any problems with corrosion or sludge that would not apply to the heat exchanger in an indirectly cooled installation anyway In exactly the same way the calorifier would have to be suitable for sea water and probably have a sacrificial anode.
It would be necessary to circulate the hot water from the engine with a pump as with the Bukh engines or you would have to separate the water leaving the engine itself from the water flowing through the bypass, routing the former through the calorifier before combing the two flows again.
If you convert to indirect cooling you will have to find room for the heat exchanger and the calorifier. Conversion to indirect cooling will also entail the fitting of a fresh water pump to the engine, as well as changes to the cooling system layout.
As already said the water temperature would be lower than with a fresh water cooled engine.
I don't see any problems with corrosion or sludge that would not apply to the heat exchanger in an indirectly cooled installation anyway In exactly the same way the calorifier would have to be suitable for sea water and probably have a sacrificial anode.
It would be necessary to circulate the hot water from the engine with a pump as with the Bukh engines or you would have to separate the water leaving the engine itself from the water flowing through the bypass, routing the former through the calorifier before combing the two flows again.
If you convert to indirect cooling you will have to find room for the heat exchanger and the calorifier. Conversion to indirect cooling will also entail the fitting of a fresh water pump to the engine, as well as changes to the cooling system layout.
mick54321
New Member
i thought about diverting the raw water outlet that goes down the exhaust, to the calorifier and then back down the exhaust outlet. i was concerned about corrosion. Does anyone have any idea about the exhaust outlet temp of the raw water?
VicS
Well-Known Member
[ QUOTE ]
thought about diverting the raw water outlet that goes down the exhaust, to the calorifier
[/ QUOTE ] That is going to be the hot water, at say 70 something C, from the engine itself mixed with cold water coming via the bypass I suspect. It will probably be to cool to make it any good as the fed to the calorifier unless you only want luke warm water. Hence the reason I suggested the two flows have to be separated. The Burk takes hot water from the engine circulates it through the calorifier before returning it to the engine. At least that's my understanding.
thought about diverting the raw water outlet that goes down the exhaust, to the calorifier
[/ QUOTE ] That is going to be the hot water, at say 70 something C, from the engine itself mixed with cold water coming via the bypass I suspect. It will probably be to cool to make it any good as the fed to the calorifier unless you only want luke warm water. Hence the reason I suggested the two flows have to be separated. The Burk takes hot water from the engine circulates it through the calorifier before returning it to the engine. At least that's my understanding.
Slipstream 34
Well-Known Member
I have a Bukh 24 DME and had the same reservations and queries as yourself.
To combat the corrosion issues I fitted a Quick stainless steel calorifier which has a stainless steel heating coil - so shouldn't corrode.
I had a long chat with the Bukh people and discussed using the raw water outlet that goes down to the exhaust but there is very little pressure/flow rate to give an effective heat source.
The only real option is to fit an electric circulation pump as already mentioned (wired into the ignition circuit).
We get piping hot water ie you can't hold your hand under the hot tap, after about 15 mins at cruising speed.
To combat the corrosion issues I fitted a Quick stainless steel calorifier which has a stainless steel heating coil - so shouldn't corrode.
I had a long chat with the Bukh people and discussed using the raw water outlet that goes down to the exhaust but there is very little pressure/flow rate to give an effective heat source.
The only real option is to fit an electric circulation pump as already mentioned (wired into the ignition circuit).
We get piping hot water ie you can't hold your hand under the hot tap, after about 15 mins at cruising speed.
FAITIRA
Well-Known Member
Depends if the calorifier is made of compatible materials, mine is (ISOTHERM) and can be used with salt water, as it says in the 'destructions'.
johnphilip
Well-Known Member
Why not consider fitting the both the heat exchanger and calorifier? Yes as suggested above you may get sludge build up in the heat exchanger, but isn't that better than building up blockages inn the engine block. The system on our old Bukh was an electric pump taking nice fresh water around the engine, calorifier and heat exchanger and the salt went from the engine pump through the heat exchanger and back to the exhaust. This was a retro fitted system installed by the previous owner and worked well. We did have to strip the heat exchanger every 3 or 4 years but the 22 year old engine was still running sweetly when we sold the boat. The only thing to watch is that the heat exchanger has to be chosen with care as the flow from the pump for seawater cooled engine is rather less than is normal for an indirect system. I think it was EC Smith put us right on this one.
moodymadness
Member
The bukh pump assisted system works just fine with piping hot water via raw water through calorifier. Stainless steel heating coil and tank was recommended as the best option. All relatively cheap in boating terms!
Pete
Pete
paulwitney
Active Member
I have a Volvo 2002 raw water cooled engine that takes the the water from the thermostat outlet to the calorifier - (hot water tank) and then back to the exhaust elbow. Absolutly no problem! 20 - 30 minutes of engine time gives plenty of water for two hot showers and some left over for washing up! The calorifier is all stainless, is over 24 years old and still going strong. There is NO metalic connection between tank and anything else. All connecting hoses are rubber.
pvb
Well-Known Member
I'm not even sure that it's necessary to have an all-stainless calorifier, especially as a lot of the cooling pipes on Volvo engines are copper.
paulwitney
Active Member
I'm sure copper would do fine but these days whatever is the cheapest and is going to last would do me. The cost in labour of having the tank made is probably the biggest factor! Raw water will give you a hot shower though!!!
mick54321
New Member
Thanks for the advice
Modulation
Well-Known Member
I considered doing this with a raw water cooled 2gm 3 years ago and posted here to see what the cognoscenti felt. My replies were similar to yours but Snowleopard ( I think it was he) recommended a way of doing it with the "exhaust" water being used before it was mixed with the by-passing cold raw water. He even sent me a diagram - and it made a lot of sense to me. I talked it through with Barrus at one of the boat shows and they puffed a bit and said they couldn't recommend it - but when pressed could give no sound and logical reason why. An inability to think outside the box, maybe?
In the event the calorifier I fitted had a small immersion heater - c 1.25kw - and I've since relied on that. This is small enough not to trip the supply in French marinas - an issue for me. It's less elegant than the engine heated approach but beats running the engine just to get DHW. This year I may get around to using Snowleopard's approach!
Try PMing him and see if he still has that sketch. If he has can you forward it to me.
Best of luck /forums/images/graemlins/smirk.gif
In the event the calorifier I fitted had a small immersion heater - c 1.25kw - and I've since relied on that. This is small enough not to trip the supply in French marinas - an issue for me. It's less elegant than the engine heated approach but beats running the engine just to get DHW. This year I may get around to using Snowleopard's approach!
Try PMing him and see if he still has that sketch. If he has can you forward it to me.
Best of luck /forums/images/graemlins/smirk.gif
vyv_cox
Well-Known Member
Copper heating coil in the calorifier is no problem at all. My all-copper calorifier, used with a raw-water cooled system, was perfectly OK when I removed it. I chopped it open to see if there was any corrosion - none evident. The only reason I removed it was that I couldn't remove the blanking plate for an immersion heater - it had corroded in place on the fresh-water side.
wotayottie
Well-Known Member
The thermostat opening temp on your raw water cooled engine will be in the 50 to 60 deg range, but since this is also the recommended setting for the thermostat on your domestic hot water, yopu can see there should be no temp problem. Sure it will heat up slower than if powered by the 90 deg cooling circuit of an indirect cooled engone but it will still get there.
On my 2003, the feed to the calorifier is the bleed off that is opened by the engine thermostat when it gets up to temp. Inevitably this is a pretty small flow - so small in my case that it doesnt work without a pump. If the calorifier is bearer to the engine than mine is (15 ft run) or if the engine is overheating, then you might well get away without a pump.
There is no electric pump designed for this use - at least none that I can find. The one usually recommended by dealers says not for salt water use on its blurb.
On my 2003, the feed to the calorifier is the bleed off that is opened by the engine thermostat when it gets up to temp. Inevitably this is a pretty small flow - so small in my case that it doesnt work without a pump. If the calorifier is bearer to the engine than mine is (15 ft run) or if the engine is overheating, then you might well get away without a pump.
There is no electric pump designed for this use - at least none that I can find. The one usually recommended by dealers says not for salt water use on its blurb.
Slipstream 34
Well-Known Member
"There is no electric pump designed for this use - at least none that I can find. The one usually recommended by dealers says not for salt water use on its blurb. "
The one recommended and supplied by Bukh is a pump with a ceramic impellor with a magnet attached, driven by another magnet outside the pump housing. This is for use with salt water and has given trouble free service. Only trouble is it is so quiet you need to feel for vibration when its running.
Not cheap it was about £80.
The one recommended and supplied by Bukh is a pump with a ceramic impellor with a magnet attached, driven by another magnet outside the pump housing. This is for use with salt water and has given trouble free service. Only trouble is it is so quiet you need to feel for vibration when its running.
Not cheap it was about £80.