Does anyone have experience replacing or even repairing a heat exchanger. I was told ours on our generator (FP)may be leaking freshwater. Any suggestions or direction would be helpful. Jeffrey J. Schwartz
heat exchanger
- Thread starter Mystiko
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Radiator Shop Is One Option
Dear Mystico: Recently a local radiator shop in my area that also did work with marine heat exchangers was able to repair my diesel engine's heat exchanger. All the tubes inside the exchanger were still in good condition, but the areas around the copper welds had corroded through, allowing comingling of coolant and sea water. The shop was able to repair with solder. In my case it was easy for me to remove the exchanger myself and bring it to the shop. I don't know about generator heat exchangers, but a radiator shop might also be an option for you to consider. Local marine mechanics should be able to refer you to shops that are good at heat exchangers. In my case, the repair was a lot less $ than a new unit. And the lead time for a new unit was several week vs. two days for the repair. If repaired, verify that the shop before giving it back to you has performed a pressure test. regards,
Dear Mystico: Recently a local radiator shop in my area that also did work with marine heat exchangers was able to repair my diesel engine's heat exchanger. All the tubes inside the exchanger were still in good condition, but the areas around the copper welds had corroded through, allowing comingling of coolant and sea water. The shop was able to repair with solder. In my case it was easy for me to remove the exchanger myself and bring it to the shop. I don't know about generator heat exchangers, but a radiator shop might also be an option for you to consider. Local marine mechanics should be able to refer you to shops that are good at heat exchangers. In my case, the repair was a lot less $ than a new unit. And the lead time for a new unit was several week vs. two days for the repair. If repaired, verify that the shop before giving it back to you has performed a pressure test. regards,
Go to a boiler shop ... or a heat exchanger shop..
Depending on the tubing arrangement configuration most heat exchangers are usually an easy repair (seal welding, re-rolling the tubes, etc.) ... including simply blocking/plugging the errant tube. Strongly suggest that you only take an expensive heat exchanger to a radiator shop or local 'welder', etc. ..... as a last resort.
Depending on the tubing arrangement configuration most heat exchangers are usually an easy repair (seal welding, re-rolling the tubes, etc.) ... including simply blocking/plugging the errant tube. Strongly suggest that you only take an expensive heat exchanger to a radiator shop or local 'welder', etc. ..... as a last resort.
I would guess that just like any other industry
I would guess that just like any other industry you can find both good and bad radiator shops. We had a relationship with a good one and they did excellent work for use. A radiator shop may be easier to find and if you ask the right questions you will do just fine with such a shop. All the best, Robert Gainer
I would guess that just like any other industry you can find both good and bad radiator shops. We had a relationship with a good one and they did excellent work for use. A radiator shop may be easier to find and if you ask the right questions you will do just fine with such a shop. All the best, Robert Gainer
Expertise is what Im getting to .....
If a cheapy heat exchanger as would be found in most marine engine applications is assembled by '*rolling* the tubes into the tubsheet' and that mechanical seal of the tube to tubsheet is now suspect, a boiler shop can re-roll that interface as they would have the rolling equipment commonly available. A radiator shop (serving an industry that nowadays is mostly using non-repairable and 'disposable' cores) probably wont have this expertise and will only have the recourse to silversolder, etc. "Good" radiator shops are now getting to be as rare as many many other 'craftsmen' that have been displaced by cheap 'disposables' and 'imports', etc. If the heat exchanger is corroded past is 'normal' allowance tolerances, a boiler shop may be in the position to at least offer an economical alternative that will be a direct 'function' replacement ... and can correctly calculate all the parameters: approach temps., LMTD, surface area, etc. based on the specific thermal coefficients of transfer of the 'new' offering, etc. versus the output heat characterists of your engine. I dont think that even a 'good / old-fashioned' radiator shop would be able to give this 'value added' service (but you never know until you get there). ;-)
If a cheapy heat exchanger as would be found in most marine engine applications is assembled by '*rolling* the tubes into the tubsheet' and that mechanical seal of the tube to tubsheet is now suspect, a boiler shop can re-roll that interface as they would have the rolling equipment commonly available. A radiator shop (serving an industry that nowadays is mostly using non-repairable and 'disposable' cores) probably wont have this expertise and will only have the recourse to silversolder, etc. "Good" radiator shops are now getting to be as rare as many many other 'craftsmen' that have been displaced by cheap 'disposables' and 'imports', etc. If the heat exchanger is corroded past is 'normal' allowance tolerances, a boiler shop may be in the position to at least offer an economical alternative that will be a direct 'function' replacement ... and can correctly calculate all the parameters: approach temps., LMTD, surface area, etc. based on the specific thermal coefficients of transfer of the 'new' offering, etc. versus the output heat characterists of your engine. I dont think that even a 'good / old-fashioned' radiator shop would be able to give this 'value added' service (but you never know until you get there). ;-)
All very true RichH but what I was going after is
All very true RichH but what I was going after is the economics of the thing. I would think that if you needed extensive work it would be more cost effective to replace the heat exchanger. But yes you are right and a radiator shop does not have the same equipment and skill set as a boiler shop so in a restoration or some other circumstance where parts are not available and you need to build something a boiler shop would be a better bet. All the best, Robert Gainer
All very true RichH but what I was going after is the economics of the thing. I would think that if you needed extensive work it would be more cost effective to replace the heat exchanger. But yes you are right and a radiator shop does not have the same equipment and skill set as a boiler shop so in a restoration or some other circumstance where parts are not available and you need to build something a boiler shop would be a better bet. All the best, Robert Gainer
Does it make a difference to the answers to this
if you note he was asking about his "generator?" It could be that different answers would apply than talking about engine HXs.
if you note he was asking about his "generator?" It could be that different answers would apply than talking about engine HXs.
All depends on the original construction of the
exchanger. Most typical small exchangers are simple "u" tube bundles with a single tube sheet ... all made of light weight/gage materials. LIght gage/walled components have no 'corrosion allowance' and thus are not that readily 'repairable'. Rarely are such exchangers ever welded or soldered together as 'hand work' makes such expensive. The typical assembly is by 'rolling' the tubes into the tubesheet .... simply expanding the tube diameter so it fits tight into the tubesheet --- all the 'joints' are mechanical. If one or two tubes is leaking the simple practice is to simply PLUG the offending tube and thus operate on a slightlly less thermal efficiency - all depends on what % of the tubes need to be plugged. Even if this particular exchanger is 'shot' the intense competition within this industry should allow one to obtain a relatively cheap 'functional' replacement. For example Indigo Electronics and Moyer Marine offer domestic heat exchangers for 30-50 hp engines that are made of simple piping and will be in the price range of hundreds instead of those OEM exchangers made from 'castings' @ '$ thousands'. At the present time the US dollar is so weak vs. other currencies and since most OEM replacement exchangers are made overseas, their prices just due to the currency exchange can be prohibitive. So, one might be able to spend a relatively small amount for a domestic made exchanger ... but will probably have to mount it in a remote location (such as on an adjacent bulkhead, etc.) ... better than getting ripped due to currency imbalances. Radiator shops are quickly being relegated to obsolescence .... totaly disposable light-weight cores, plastic heads, etc. ..... ie. all 'cheap and dirty' structure and components that are simply too 'thin' to repair. And as these 'craftsmen' dissapear ... no one is replacing them ('cept accountants).
exchanger. Most typical small exchangers are simple "u" tube bundles with a single tube sheet ... all made of light weight/gage materials. LIght gage/walled components have no 'corrosion allowance' and thus are not that readily 'repairable'. Rarely are such exchangers ever welded or soldered together as 'hand work' makes such expensive. The typical assembly is by 'rolling' the tubes into the tubesheet .... simply expanding the tube diameter so it fits tight into the tubesheet --- all the 'joints' are mechanical. If one or two tubes is leaking the simple practice is to simply PLUG the offending tube and thus operate on a slightlly less thermal efficiency - all depends on what % of the tubes need to be plugged. Even if this particular exchanger is 'shot' the intense competition within this industry should allow one to obtain a relatively cheap 'functional' replacement. For example Indigo Electronics and Moyer Marine offer domestic heat exchangers for 30-50 hp engines that are made of simple piping and will be in the price range of hundreds instead of those OEM exchangers made from 'castings' @ '$ thousands'. At the present time the US dollar is so weak vs. other currencies and since most OEM replacement exchangers are made overseas, their prices just due to the currency exchange can be prohibitive. So, one might be able to spend a relatively small amount for a domestic made exchanger ... but will probably have to mount it in a remote location (such as on an adjacent bulkhead, etc.) ... better than getting ripped due to currency imbalances. Radiator shops are quickly being relegated to obsolescence .... totaly disposable light-weight cores, plastic heads, etc. ..... ie. all 'cheap and dirty' structure and components that are simply too 'thin' to repair. And as these 'craftsmen' dissapear ... no one is replacing them ('cept accountants).
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