Low cost pool heat exchangers

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R_p_ryan

Senior Member
Joined
Dec 11, 2014
Messages
171
Location
USA
Vessel Name
Shellbourne
Vessel Make
1978 Mainship 34 Perkins T6.354
Is there any reason why a low cost titanium shell and tube heat exchanger should not be used to cool a marine diesel? These units are primarily for salt water pools with chlorine but they state they can be used for marine cooling, including oil and salt water. https://www.brazetek.com/bt-stx-85-2-titanium-heat-exchanger
At $380 and considering its titanium it seems like an ideal substitute. But there's little info online of any marine experience with them, except an old study by the navy on titanium fouling with growth at low temperatures.

My air charge cooler is an old Bowman unit with a cast iron sleeve that is raw water cooled and was very badly corroded on the inside. I could imagine the engine vibrations could be a factor with a lightweight cooler like the one above.


Thanks,
Robert.
 
If you're handy at fabrication it wouldnt be a problem. It really doesnt need to be bolted to the engine, it could be on a stand or bulkhead, so vibration wouldnt be an issue. It does need to be big enough and able to flow enough raw and fresh water to get the job done. Heat rejection calculations are available to check that. Most folks think diesel engines and associated systems, very much especially marine diesels, are akin to rocket science. It just aint so :)
 
SCOTTEDAVIS said:
Not for use in:
● Salt water pools.
● Marine applications.
● Liquids containing hydrochloric acid, sulphuric acid and other chemicals known to corrode 316L stainless steel.

http://www.brazetek.com/docs/pdf/st-quick-sizing.pdf
Click to expand...

They offer stainless and titanium. I think those specs are for the SS versions. For the ti version they have:
Applications:
Hot Tub/Spa/Swimming Pool Heating
Marine (Salt Water) Applications
 
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Sized appropriately it should work fine. As Kulas said this stuff ain't rocket science, especially heat exchangers.
 
R_p_ryan said:
They offer stainless and titanium. I think those specs are for the SS versions. For the ti version they have:
Applications:
Hot Tub/Spa/Swimming Pool Heating
Marine (Salt Water) Applications
Click to expand...


I don't know enough about Ti, I wonder how such a noble metal plays with other metals in in our engines. I like the prices and the idea of using non boat stuff. Looking for information from others.
 
The Bowman stuff is available here in the USA, they have "stockists" here. A little pricey tho. I made my own replacement housing some years ago out of PVC pipe and bronze nipples (my aluminum end caps were fine) It holds the regular 4" x 10" core and fits right where it belongs.
I has worked fine for years since w/o worries about rusted off hose stubs sinking your boat. Just a few bucks of materials makes a better than original housing. I think I posted a couple of pictures / drawings a while ago.
 
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Brooksie said:
The Bowman stuff is available here in the USA, they have "stockists" here. A little pricey tho. I made my own replacement housing some years ago out of PVC pipe and bronze nipples (my aluminum end caps were fine) It holds the regular 4" x 10" core and fits right where it belongs.
I has worked fine for years since w/o worries about rusted off hose stubs sinking your boat. Just a few bucks of materials makes a better than original housing. I think I posted a couple of pictures / drawings a while ago.
Click to expand...

Fantastic - I just cleaned mine out and contemplated something similar. I'm glad to hear it's working well' because cast iron seems like a poor material and pvc seems more logical.
 
I use a brazetek exchanger for my cabin bus heater loop off the engine coolant.

Seems made well enough and no visible corrosion after 2.5 years living in the bilge...and that is their generic cheaper model. Not sure what it is made out of.
 
I dunno, in their comprehensive list of applications they make no mention of engine cooling.

https://www.brazetek.com/applications

I'd certainly call them first, and you'd have to know exactly what is needed to cool your particular engine (you can look up your RW pump on Depco's site and see how many GPM it puts out at different RPM as a starting point), and even then I'd be very wary about taking such a huge gamble. Can't get my head around how this would tie into the coolant tank and overflow tank.
 
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caltexflanc said:
Can't get my head around how this would tie into the coolant tank and overflow tank.
Click to expand...

I think Robert's intent was as an air charge cooler (between the turbo and the intake to the engine). If it flowed enough air (and that would be my question...The air side does not look very big) I don't see why the concept wouldn't work with a cooler designed for this type of work. Lots of Turbo cars use aftermarket Air to water intercoolers to do the same thing. Some are factory fitted (New M3 BMW for instance). They need to be sized appropriately though for both cooling and air flow..

img_387916_0_dac87eee4170ca728fdcad4f653cafcc.jpg


flow2.jpg
 
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I'm also contemplating options for converting my exhaust manifold from raw water cooled to fresh water cooled. Where the raw water goes through the manifold I'd replumb it to go through the titanium exchanger, and then in to the wet elbow. Then add the exchanger to the fresh water loop. Others have added the manifold into the FW circuit without adding extra cooling, but I would rather have excess raw water cooling capacity and let the thermostat in the fresh water loop keep the engine at the correct operating temp.
 
Heron said:
I think Robert's intent was as an air charge cooler (between the turbo and the intake to the engine). If it flowed enough air (and that would be my question...The air side does not look very big) I don't see why the concept wouldn't work with a cooler designed for this type of work. Lots of Turbo cars use aftermarket Air to water intercoolers to do the same thing. Some are factory fitted (New M3 BMW for instance). They need to be sized appropriately though for both cooling and air flow..

img_388187_0_dac87eee4170ca728fdcad4f653cafcc.jpg


flow2.jpg
Click to expand...

Passing seawater through the shell side means chemical cleaning or disassembly is the only way to clean it. Not good. You would have to run the antifreeze coolant through those small connectors.
 
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High Wire said:
Passing seawater through the shell side means chemical cleaning or disassembly is the only way to clean it. Not good. You would have to run the antifreeze coolant through those small connectors.
Click to expand...

Actually on this type of air to water cooler, it's the air that passes through the shell side and over an internal radiator assembly that carries the cooling fluid. The picture above does not make that very clear, sorry!

You are right on the cleaning though...It would be virtually impossible to clean the radiator side easily. Chemicals would be necessary.

This brings up another caveat.....While the shell may be titanium, I seriously doubt the internal heat exchanger is (at that price). Most of those are aluminum and would likely fail in short order in a salt water environment..(hence the Manufacturers warning). Water intrusion into your engine intake could then result in catastrophic engine failure..
 
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The OP has a Perkins T6.354, and Googling around I find that the NA001545 heat exchanger for that engine is $500 to $600, compared to the $380 for the pool one.

Really? Is there a world in which potentially saving $120 is a smart trade-off between installing something that was engineered for the particular application versus something that has no equivalent engineering, history, or installation support; where the cost of catastrophic failure is potentially the entire loss of the vessel (with potential loss of life); where survey results and/or resale value would not matter? I don't live in that world, but maybe it's inhabitants have a noticeable mark or flag that would allow me to give them a very wide berth.

Edit: Oh wait, yes they do - these are the Darwin award recipients. Still would like that early warning system though.
 
refugio said:
The OP has a Perkins T6.354, and Googling around I find that the NA001545 heat exchanger...
... these are the Darwin award recipients. Still would like that early warning system though.
Click to expand...

Oh come on, let's not start quoting darwin awards. To be clear - the post is a question about whether or not a titanium pool heat exchanger can used to cool a marine diesel.

The titanium exchanger I was looking at is interesting. I was hoping to hear positively either success or failure in its use on boats. Ridicule for contemplating a cost efficient alternative, or in my case upgrade, was the last thing I was expecting.

My Mainship has a stock domestic water that has the coolant loop running through it. If that failed it could drain my entire fresh water coolant loop due to the higher pressure in it. The chain is only as strong as its weakest link. Theory isn't good enough, it needs to have years of experience to dictate if it will work - with the dimensions of thermal stress, corrosion, fouling, vibration, resistance to chemicals in its vicinity. This is why I'm asking the question. Let's say several people replied saying they work brilliantly and are superior to the stock ones that came with my 1977 engine. I'd want to know. Or let's say a single person replied saying "I tried it but it failed after a season due to bad weld joints" I'd be just as delighted with either answer.

I traverse a treacherous bar regularly that has claimed lots of lives. I also worked search and rescue for five years and pulled people, dogs, and bodies out of the water. When it comes to boating I'm a safety freak. Which is why I don't like my raw water cooled exhaust manifold. Or the cast iron sleeved intercooler. Because these can corrode and fail when under it's greatest stress, like trying to maneuver around a sneaker wave like the one I videod two days ago (see http://www.trawlerforum.com/forums/s36/san-francisco-potato-patch-23307.html

The part number you quoted, from Mr. Cool says:
"Please note that this part is not intended for salt water. If you're using this part in salt water, please purchase the copper nickel version of the part"

These are the details I look for, and I'll continue to think about creative improvements and ask people for feedback.
 
R_p_ryan said:
Oh come on, let's not start quoting darwin awards. To be clear - the post is a question about whether or not a titanium pool heat exchanger can used to cool a marine diesel.

The titanium exchanger I was looking at is interesting. I was hoping to hear positively either success or failure in its use on boats. Ridicule for contemplating a cost efficient alternative, or in my case upgrade, was the last thing I was expecting.

My Mainship has a stock domestic water that has the coolant loop running through it. If that failed it could drain my entire fresh water coolant loop due to the higher pressure in it. The chain is only as strong as its weakest link. Theory isn't good enough, it needs to have years of experience to dictate if it will work - with the dimensions of thermal stress, corrosion, fouling, vibration, resistance to chemicals in its vicinity. This is why I'm asking the question. Let's say several people replied saying they work brilliantly and are superior to the stock ones that came with my 1977 engine. I'd want to know. Or let's say a single person replied saying "I tried it but it failed after a season due to bad weld joints" I'd be just as delighted with either answer.

I traverse a treacherous bar regularly that has claimed lots of lives. I also worked search and rescue for five years and pulled people, dogs, and bodies out of the water. When it comes to boating I'm a safety freak. Which is why I don't like my raw water cooled exhaust manifold. Or the cast iron sleeved intercooler. Because these can corrode and fail when under it's greatest stress, like trying to maneuver around a sneaker wave like the one I videod two days ago (see http://www.trawlerforum.com/forums/s36/san-francisco-potato-patch-23307.html

The part number you quoted, from Mr. Cool says:
"Please note that this part is not intended for salt water. If you're using this part in salt water, please purchase the copper nickel version of the part"

These are the details I look for, and I'll continue to think about creative improvements and ask people for feedback.
Click to expand...

Absolutely....looking for smart alternatives in a forum like this is what it is all about for me.

Some are here fo primarilyr entertainment, some of social needs.....me I am looking for better, cheaper ways to boat.

If I wanted a part number I would ask for it, asking whether something non-standard will work or not demands thinking outside the box....

All to often those that choose not to or can't come back with the personal attacks on the sanity of those exploring alternatives.

Thus why I started the bad boys club here...for those that refuse to conform in totality.

I have seen dozens of non standard, non manufactured variations of keel coolers which are just simplified heat exchangers. The concept is simple but the devil is in the details. If you know how much heat needs to be carried away...then you can calculate or estimate what in the way of a heat exchanger you need.

Bottom line...OEM isn't the only solution..nor are only aftermarket lookalikes.

Several here have recently or further back switched to electric pumps instead of on engine salt water pumps for their genset with good results. Out of the box solutions and no one was slinging the mud at them.
 
My Mainship has a stock domestic water that has the coolant loop running through it. If that failed it could drain my entire fresh water coolant loop due to the higher pressure in it. The chain is only as strong as its weakest link
Click to expand...
A little thread drift....
As an FYI I used low pressure steam hose (rated at 150 psi) for my long run to the water tank on my Mainship. That was one part of the puzzle I never worried about.
 
Having gone through 17 charge air coolers in a new installation (long story for too many beers to tell) You must make sure that the air side can take the boiling of the charge air gasses, and the corrosion on the water side that will be boiling also (whatever coolant you use) is 'safe' to use for that metal While its boiling. Charge air coolers have to dissipate a boat load of heat fast. The thermal expansion and coolant get very aggressive inside the cooler.

When I cut one of my failed charge air coolers apart the panels looked like Swiss cheese. Hundred of tiny small holes all over the place. Turned out we were using the wrong coolant, which was eating up the new fangled coolers. MTU wasn't happy. Neither was the company. But we learned to use 'MTU approved' coolant after that! (Much to the Port Engineers embarrassment)

As Refugio inferred: The coolers have specific cooling capacities as far as amount of BTUs they can slough off, how much water flow (there can actually be too much flow!). And how much delta can be achieved.

I think since you are running a dinosaur Perkins you have MUCH more leeway for error. But this IS trial and error.

Can you find out what the BTU exchange capacity of the old cooler is? If the new cooler meets the same capacity then it should work. Then you have to ensure the coolant doesn't eat the cooler out also.
 
RPR

Why not just bite the bullet and buy a new unit suited for the engine? The current setup has lasted nearly 40 years if I read your posts correctly. Sure sounds like it worked very well.

As discussed, you can make it better by plumbing the manifold for coolant. And you can install a fresh water flush for the cooler. These are sensible upgrades and would be appreciated by the next owner.

But the other stuff you are contemplating are out of the norm and a step backwards IMHO.
 
R_p_ryan said:
The part number you quoted, from Mr. Cool says:
"Please note that this part is not intended for salt water. If you're using this part in salt water, please purchase the copper nickel version of the part"
Click to expand...
Ok, that's the NA001545CN - another $100.

But you are completely missing the point, which is that a saltwater pool is not the same as the ocean.

"But remember, saltwater swimming pools ARE NOT chlorine-free pools. A salt water system simply means adding pool salt to make pool chlorine by installing a pool chlorine salt water generator."​

As with any pool or spa, you need to use acid and Sodium Bicarbonate to keep the pH and total alkalinity in balance within a rather narrow range. Or it will rapidly eat holes in the thin metal.

The pool - saltwater or chlorine - has an aggressive program to kill any growth. It also has a massive filter to keep everything out of the exchanger.

The exchanger you proposing is not serviceable. Heck, it isn't even inspectable. It lacks a drain fitting (though that can be dealt with). It lacks a pencil zinc (maybe there's a place to cut a hole and weld on a nut for a zinc, but what size?).

Hey, but maybe you're on to something. And hundreds of engine manufacturers and tens of millions of boats have completely missed out on shaving a few bucks with this awesome cooling idea. Have at it. After all, you've done your "research" - you asked some random folks on an Internet forum. What could go wrong?

Oh, wait - maybe you want to use your vessel in cold water?

"There is a rough rule of thumb that says a simple fixed tube sheet configuration can only be used for cases where the inlet temperatures of the two streams do not differ by more than 100 'F. Obviously, there must be many qualifications made to such a flat statement, recognizing the differences in materials and their properties, temperature level of operation, start-up and cycling operational procedures, etc."​

The Darwin committee has your award on temporary hold pending the outcome of your "upgrade". The good news is, you don't have to be present to win!
 
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Since when does ASKING questions, THINKING out of the box or the failure of one engine component line someone up for the Darwin Award? Even jokingly, enough with a quick, first reference to it.

Lots of disgreement from others with the premise without insulting the OP.

I applaud him for bringing up the idea even if proven not likely to succeed.

A few more good points and he may abandon the idea....if after pages of disagreement like some on here will do despite numerous good links to reality... then I will be the first to vote yes for some kind of similar award.. :thumb:
 
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psneeld said:
Since when does ASKING questions, THINKING out of the box or the failure of one engine component line someone up for the Darwin Award? Even jokingly, enough with a quick, first reference to it.

Lots of disgreement from others with the premise without insulting the OP.

I applaud him for bringing up the idea even if proven not likely to succeed.

A few more good points and he may abandon the idea....if after pages of disagreement like some on here will do despite numerous good links to reality... then I will be the first to vote yes for some kind of similar award.. :thumb:
Click to expand...
I'm all for thinking outside the box, but there simply has to be a point where - when it may (will?) cause loss of life - members will step up and say "No". And I feel this is that point, if not for the OP then for anyone else who ends up in this thread after Googling "pool heat exchanger boat".

In my opinion, the raw water side of complex engine plumbing is not a place to look for "innovation". Patio furniture and carpeting on deck? Sure. Household or camping appliances in the galley? Sure. Using a sex object as a toilet paper holder? Um, ok. But replacing an engineered solution for keeping water out of the boat while removing excess heat from an engine just to potentially save some a couple hundred dollars? "Hell No".
 
Thinking death in this thread is a stretch.

Advise not condemn. At least that is what I have been reminded of. And some souls tossed for being so direct.

Most boaters will die of many reasons...probably not the direct result of a heat exchanger.
 
psneeld said:
Thinking death in this thread is a stretch.

Advise not condemn. At least that is what I have been reminded of. And some souls tossed for being so direct.

Most boaters will die of many reasons...probably not the direct result of a heat exchanger.
Click to expand...
A stretch? Maybe, but isn't life safety really the #1 consideration?

Sure, there may not have been many deaths as a direct result of heat exchanger failures. But I would assert that's because marine heat exchangers have evolved over...what, 100 years? They have been designed so that if they fail, the results won't be catastrophic. Think of the alarms boats have. Engine overtemp, coolant overtemp, exhaust overtemp, coolant flow, bilge water level. What is the equivalent in a pool? Microswitches that instantly turn power / heating / circulation off. And that's where the cost of failure is a leakdown, not a boat sinking. And you know that most sinkings are at the dock - this use case seems most likely to happen away from the dock and operating at higher loads.

I think this is one of the most dangerous ideas ever floated on a boating forum and it deserves to be called out as such. But I can understand and accept that you don't agree.
 
sunchaser said:
RPR

Why not just bite the bullet and buy a new unit suited for the engine? The current setup has lasted nearly 40 years if I read your posts correctly. Sure sounds like it worked very well.

As discussed, you can make it better by plumbing the manifold for coolant. And you can install a fresh water flush for the cooler. These are sensible upgrades and would be appreciated by the next owner.

But the other stuff you are contemplating are out of the norm and a step backwards IMHO.
Click to expand...

My concern is adding too much heat to the raw water system by just adding the manifold into the freshwater circuit. If there was a larger sized OEM heat exchanger designed for the extra heat added from the manifold then it would be a simple and appropriate solution. I haven't seen this, so I'm considering alternative ways to increase the cooling capacity, seeing a cheap titanium heat exchanger sounded interesting. (to refugio it sounds so stupid it's worthy of ridicule, but I am actually a reasonably accomplished engineer and I've faced similar criticism for both - ideas that have worked and ideas that have not. So I've learned to notice yet ignore such ridicule).

I have heard of two situations where the manifold was just added, in one case it was perfectly fine, in the other there were issues which led the owner to repower. I think if the cooling circuit is in pristine shape then there is enough cooling capacity, however if there are any issues - from a worn water pump cam to fouling in the air charge cooler, my guess is the system overheats.

As Cappy points notes it about the BTU of the existing system, the addition of the manifold and the capacity of any added exchanger. I don't know those numbers. I haven't seen a "generic" marine-purpose heat exchanger with BTU ratings.

Thanks,
Robert
 
On several different occasions I was involved with designing heat exchangers for industrial use and engine cooling. As one would expect, the playing field is wide open but some basics apply. Two key elements are what are you trying to cool/heat with what medium whether air or solution.

Land based diesel and gas air cooler applications on the incoming side have only to deal with air and at what elevation and temperature. Marine diesels have it a lot tougher as not only is the incoming air a variable but the cooling medium can be fresh, salt or coolant liquid with associated thermal and corrosive issues.

The sizing for the cooler (a radiator if you will) can be easily defined for the un fouled state once air flow, pressure and cooling medium are defined. This is the purpose of proper marinization.

A test for the marine engine builder in this day is the dyno. Not only for emissions compliance but in this case to insure the various coolers and heat exchangers perform at rated fuel burn and expected air and water temperatures.

I do know that the same engine and associated coolers on my vessel were designed for use in the Red Sea, warmer waters than the PNW for sure.

So with all this blather, what is my point? The same as I mentioned in another related thread. Think outside the box and bypass the air cooler completely and see how things behave. Then you have a go forward point of reference for non engineered hit and miss air cooler pursuits. Maybe then some new knowledge can be gained and verified.

On a different note, I do know that a jacket water cooler is a very different unit than a raw water cooler. Using coolant in the same cooler as designed for raw water will effectively de-rate the engine, not necessarily a bad thing. But kind of like bypassing the cooler entirely.
 
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