I have a calorifier installed and connected between the thermostat bypass to the exhaust elbow on a Bukh DV24 raw water cooled. I get warm water after a long motor, however researched a bit more into it and it seems since the engine runs low temps, this isn't as effective as possible.
i even went to the point of putting a bypass hose instead of calorifier with a temp probe to multimeter and went for a spin, yep not hot, just warm.

Bit of research and found this

coxeng.co.uk/engine/calorifier-installation/

Appears there is other ports on block to take hot water off prior to thermostat mixing with cool bypass water.

I've searched my block/manifold and found 3 possible points, so looking for advise of which ones to use, and other watch outs.

First, 2 plugs have this sticker, 1 on underside of thermostat housing, and other on engine block at rear lower half of engine. Not sure which is hot or cold side as suggested in Cox website? And Not sure why upside down in photo ??


3rd on is under the exhaust manifold just before the elbow....no sticker I can see




Sticker and plug on block...my guess is cold side






Plug on underside of thermostat housing, and once upon a time a sticker the same as first...I really shouldn't of peeled it off.. and I guess hot side?






3rd plug at exit of exhaust manifold before elbow bolts on. I guess it has a mixture of gas and water, could it be used as return from calorifier?

Note, flash makes it look rustier than it really is!!

So the engineer in me says take off water near thermostat, it's the highest place, and should be the hottest as that's where the thermostat does it's job, and plumb to the calorifier, with a inline pump (as per cox website on the return side) back to the block, lowest point on block, but then why not back to the manifold near exhaust elbow?..

Now I guess you need to fill the calorifier with enough water that the pump creates suction, guessing the pump should be lower than the calorifier to be primed? but if there's air bubbles in there do they final purge through out exhaust? Or create a air block somewhere? Or the pump doesn't have enough suction to draw from engine? Note, not a diaphragm pump, and would a centrifuge pump could just cavitate if not 100% full of water, noting when I stop my engine, a lot of water runs out, and I would need to prime every time.? Sure not?


Lots of questions there!

Finally, on the old system, there appears to be a siphon break(U shaped tube with small pipe off top between the bypass pipe and calorifier input, and it had a small pipe running back to a through hull above waterline. Was this to remove air bubbles, or stop thermo siphoning of hot water back to engine? Can't see what damage it could do if it wasn't there...but it is there.
Do I need to add something similar in new setup? Doesn't mention it in cox website. And do I leave the thermostat bypass connected directly with exhaust elbow?

So, anyone with experience with calorifiers and Bukh engines? Many searches haven't found anything yet, Cox engineering is the best I found.

Hi Cabron,
I have a Bukh 24 and have a made my own hot water system doing a very similar thing to the Cox website. I can get my HW tank to 45 deg C with no problems, have had it at 50 deg C, however I usually have it set to 40 deg C. I use the 2 ports you have shown, under the thermostat for water out and into the block for the return, each line has a manual valve fitted to allow isolation of the HW system when system is not in use or when temperature has been achieved, just in case a leak develops. I asked Bukh at Taren Point if the port on the block was the correct place to return the water and they said "thats what its there for".

I have a 40 litre tank and it takes about 45 to 60 mins to heat up when engine is warm and I am motoring. I've found it best to start heating the water after engine is up to temp. I use the water directly from the tank, I dont mix it with cold so I'm happy with a lower temp.

My system has a plate exchanger not a calorifier as on Cox's website. I have a temperature controller monitoring the tank temp and when this makes set point it turns off the salt water circulation pump. When the HW system is heating water the engine temp drops, slightly, as it comes closer to set set point the engine temp rises above normal. Which makes sense when you consider that some of the cooling water returning to the engine could be close to 40 C temp, got to admit this makes me a little nervous but nothing bad has ever happened. In the last week or so I have replaced the salt water circulation pump, I was using a car engine cooling pump designed to handle hotter water. It failed after about 3 years, now I have a diaphragm pump, was much cheaper. So there may be a change in the systems performance, time will tell.

The system works well, it requires a bit more hands on than some of the other systems. I considered buying and fitting Bukhs system, didnt take that idea far, nothings cheap with Bukh, also thought about gas, another no, for obvious reasons.

I hope this helps, Mike

Select to expand quote

Magpiemike said..
Hi Cabron,
I have a Bukh 24 and have a made my own hot water system doing a very similar thing to the Cox website. I can get my HW tank to 45 deg C with no problems, have had it at 50 deg C, however I usually have it set to 40 deg C. I use the 2 ports you have shown, under the thermostat for water out and into the block for the return, each line has a manual valve fitted to allow isolation of the HW system when system is not in use or when temperature has been achieved, just in case a leak develops. I asked Bukh at Taren Point if the port on the block was the correct place to return the water and they said "thats what its there for".

I have a 40 litre tank and it takes about 45 to 60 mins to heat up when engine is warm and I am motoring. I've found it best to start heating the water after engine is up to temp. I use the water directly from the tank, I dont mix it with cold so I'm happy with a lower temp.

My system has a plate exchanger not a calorifier as on Cox's website. I have a temperature controller monitoring the tank temp and when this makes set point it turns off the salt water circulation pump. When the HW system is heating water the engine temp drops, slightly, as it comes closer to set set point the engine temp rises above normal. Which makes sense when you consider that some of the cooling water returning to the engine could be close to 40 C temp, got to admit this makes me a little nervous but nothing bad has ever happened. In the last week or so I have replaced the salt water circulation pump, I was using a car engine cooling pump designed to handle hotter water. It failed after about 3 years, now I have a diaphragm pump, was much cheaper. So there may be a change in the systems performance, time will tell.

The system works well, it requires a bit more hands on than some of the other systems. I considered buying and fitting Bukhs system, didnt take that idea far, nothings cheap with Bukh, also thought about gas, another no, for obvious reasons.

I hope this helps, Mike

Thanks Mike, could you PM me on the type of pump you used, the Johnson ones are a little $$, found other solar hot water circulation pumps with magnetic coupling, however salt water could take its toll and I'd prefer no little pieces floating around in block.
Cheers

Cabon,
I originally used a Davies Craig Booster pump, however as I said this pump lasted about 3 -4 years not cheap $170. I have recently fitted a cheap diaphragm pump, a bit noisier but with a DV24 rattling away in the back ground, who notices? I have also fitted a cheap garden irrigation type filter to the suction side of the salt pump as a bit of added precaution. This pump has a water temp rating of 75 deg C (from memory). I gave the system with the new diaphragm pump its first real run on Monday, after replying to you, all worked well. Tank holds 40 litres and tank temp was 23.1 deg C, it took 20 min to get it to 45 deg C. This seemed a lot quicker than with the old Davies Craig pump. So much quicker that I checked the temp of the water to make sure it was hot, seemed to be about 45 to me.
My engine temp sits around 65 normally with HW system not operating, but as the tank temp comes closer to set point the engine temp increased to about 80. I was advised by a marine diesel mechanic some time ago that the Bukh wont have any problems with this heat. But its not his engine and he gets paid to fix them.

Something I've thought about is, where the exhaust leaves the engine that pipe is bloody hot, at present its lagged, wrap some 3/8 annealed copper pipe around the exhaust manifold a few times, maybe 10 wraps or there abouts, relagg the pipework and see if this would work as a preheater for the fresh water tank, just a thought.

I have no idea how to PM you, apologies. The boats at Gunamatta Bay if that helps
Mike