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Heat Exchangers: You are hot!

Updated: Mar 19

It is an odd topic to focus on because it is highly underestimated and overly ignored.

I do not profess to be super mechanical. I rate myself proficient, self-sufficient, and likely borderline dangerous with specific tools and jobs.

I am very good at spotting when maintenance needs to be done. So, my maintenance list continues to grow, and my progress sheet remains unscathed. Procrastination about what and when rules my day, but I know that if items remain unattended, bad things happen.

So you are hot! What am I talking about?

Heat Exchangers.

Yes, that's riveting. This is what I had lured you into discussing and reveling in some rather known facts that are consistently ignored with this catchy title.

A heat exchanger service was the first thing (I got someone else to do) when I purchased my new (new-to-me) vessel. It is a regular annual occurrence within the charter company I attend. It should be something you all should think about and would appear in one of my reports as a standard recommendation unless you can tell me differently.

It is not that the engine or generator is getting hot or that the water flow looks a little restricted. Knowing the item's history and when the last service was done will extend all components' life spans for a fraction of the breakdown cost and avoid unnecessary heat-related issues.

Why the fuss?

Firstly, things grow. Yes indeed. Or constricts, to be more precise, as the saltwater calcifies into the heating tubes.

Secondly, impellers are liars.

They may seem innocent, but no, they will shed an ear to spite you and hide it somewhere.

Perhaps not the current you (owner), but the previous you (owner) and the previous you (owner) knew how to change an impeller, but that is as far as it went.

Or they did not have the time or inclination to strip down the heat exchanger to find the missing bit(s). Whichever version of you it is, left unattended, it will compound issues.

In this photograph of a YANMAR heat exchanger, we see a bit of both: a collection of bits impaled into the heating tubes plus a build-up to the convection tubes themselves, where the rubber has restricted the water flow. The aluminum casing of the heat exchanger can also break down over time but can be rebuilt by welding. Ragged edges will cause leaks.

With a simple soak in two types of solution (sublime being one item ) to clean the heat exchanger of all growth and then a flush through, you are 80% on the way to being on the better side of the engine. Finally, a new impeller and reinstallation the following year will be second nature and half the time with great peace of mind.

Experience has proven that when you find 14 ears of impellers inside the casing, someone is excellent at changing them. Each new impeller faced the same fate, as the restriction caused by the previous missing bits increased the quick demise of the next. You might be amazed at what you find.

So now - you are not so hot but amply cool, as all engines should be.

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