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Shopping for a new heat exchanger? You have come to
the right place. Here you can learn about the different types of
exchangers and then order one by
calling one of the many reviewed manufacturers and retailers of heat
exchangers.
Marine cooling heat exchangers
There are three methods employed for
water-cooled marine petrol and diesel engines: direct, heat exchanger
and keel cooling. Direct cooling of the cylinders and heads by sea-water
is unsatisfactory, because the engine - which was probably originally
designed for radiator cooling - will run too cold and the sea-water will
eventually ruin the cylinder block and heads.
Marine heat exchanger problems
Since heat exchangers contain no moving parts there is very little that
can go wrong with them except that they can get plugged with debris and
that they will become dirty. They can also develop leaks internal as
well as external. These problems will be covered in the next category of
troubleshooting. There is also the possibility that a heat exchanger is
insufficient in capacity and/or incorrectly manufactured. Those
problems, however, will show up immediately upon start-up and the
manufacturer should be contacted. In this discussion we are concerned
with the problems that could develop during normal usage.
Debris blocking
The most common problem is where enough debris accumulates in the inlet
chamber of the heat exchanger to prevent the raw water from passing
through the tubes and pick up the heat. Since all good heat exchangers
should have an existing de-mountable end cover at the inlet and it
should be a simple operation to remove this debris. If the problem
persists due to local water conditions install a good capacity raw water
strainer in the raw water inlet hose. Even better is a good hull mounted
strainer that will prevent debris from entering the system in the first
place. Obviously there is a different solution depending on whether the
raw water intake is through a seacock or a sterndrive.
Dirt build up
The more long-term problem with heat exchangers is the gradual slow
build-up of dirt on both the inside and outside of the small tubes that
form the heat transfer area. This will gradually build up as a layer of
insulation and is compensated for in every good heat exchanger design by
so called "fouling factor". This simply means the heat exchanger has
excess capacity when new and clean so it still performs acceptably when
old and dirty. However, this "fouling factor" can only go so far and
eventually a thorough cleaning of the heat exchanger may be necessary.
The most drastic solution is to remove the heat exchanger and bring it
to a radiator shop for a complete cleaning.
Make sure that the radiator shop has experience with marine heat
exchangers. Proper cleaning should be a two step operation. First clean
the unit with a strong alkaline solution to remove organic dirt such as
oil. Second, in order to remove scale, the unit should be cleaned in an
acid solution.
If a less thorough cleaning is desirable the heat exchanger can be left
in the system. The jacket waterside can be cleaned in the same way as an
automobile cooling system using any of the better radiator cleaning
solutions on the market. Using a small diameter long handle brush
similar to what is used for cleaning a rifle barrel can clean the small
tubes on the raw waterside. It is possible to acid clean the raw
waterside of the heat exchanger without removing it from the boat, but
it is messy and dangerous. The ports of the heat exchanger will have to
be plugged and the unit filled with an inhibited muriatic acid. Since an
operation like that necessitates special safety equipment and creates a
disposal problem we do not recommend that you try it unless you really
know what you are doing.
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