Manufactured by Marsh Marine...Tank Cleaning Professionals
“Our experience is your protection since 1966”
Deck Fill Protection Device
T
oday’s
larger
pleasure
craft
typically
all
have
marine
air
conditioners.
We
tend
to
take
these
creature
comfort
devices
for
granted…until
they
break!
In
this
article
we’ll
examine
a
particular
AC
problem
nearly
every
owner
will
encounter:
stopped
up
raw
water
intake
lines.
We
will
discuss
an
amazing
product
that
can
keep
your
cool
air
pumping
and
an
often
unknown
health
hazard.
Let’s
begin
with
a
simple
review
of
how
marine
air
conditioners
work.
T
here
are
basically
three
major
components
to
any
AC
system:
The
raw
water
pump,
the
compressor,
and
the
condenser
(sometimes
called
the
air
handler).
The
last
two
are
often
combined
into
what
appears
as
a
single
unit,
generally
tucked
away
beneath
a
berth
or
some
other,
usually
inaccessible,
space.
Raw
cooling
water
comes
into
the
boat
via
a
standard
through-hull
fitting
and
sea
cock.
A
small
electric
pump
then
circulates
the
water
through
hoses
to
and
through
the
air
conditioning
unit.
From
there
it
goes
overboard
through
a
second
through-hull
fitting
located above the waterline.
T
he
raw
water
circulates
through
a
simple
heat
exchanger
usually
attached
behind
the
condenser
and
resembles
a
coil
of
pipe.
The
heat
exchanger
is
actually
two
tubes,
one
inside
the
other.
The
two
are
closed
off
from
one
another.
One
tube
carries
the
raw
water;
the
other
the
compressor’s
refrigerant
gas.
As
the
cool
raw
water
circulates in the coil, it absorbs the refrigerant’s heat through the neighboring tube wall.
This
heat
exchanger
design
combined
with
the
laws
of
gas
physics
allows
the
unit
to
perform
an
interesting
dual
function.
In
hot
weather,
heat
is
taken
from
the
air
inside
the
boat
and
dissipated
into
the
cooling
water.
In
spring
or
fall
when
the
air
is
cool,
the
air
conditioner
takes
heat
out
of
the
water
and
dissipates
it
into
the
boat
to
provide
warmth. This switch from cooling to heating is known as reverse cycle operation.
R
everse
cycle
heating
works
well
until
the
sea
water
temperature
reaches
approximately
38
degrees.
Below
that
temperature
there
isn't
enough
heat
in
the
water
for
the
unit
to
work
efficiently.
Still,
reverse
cycle
heating
can
help
extend the cruising season during cool spring and fall months.
A
s
you
might
have
guessed,
or
experienced,
the
weak
link
is
this
raw
water
flowing
through
the
AC
system.
If
it
is
restricted
or
worse
stops,
the
condenser
cannot
release
its
accumulated
heat.
The
air
conditioner
begins
to
work
harder
to
maintain
the
selected
temperature
and
eventually
gives
the
fateful
error
message,
High
Head
Pressure
,
and ceases to function. Pushing the reset button will restart the unit, but only until the heat limit is again reached.
I
f
you
are
experiencing
cut
off
problems,
there
is
one
simple
means
to
trouble
shoot
the
cause.
It
isn’t
very
scientific,
but
it
works.
Place
your
hand
on
the
heat
exchanger
coil.
If
it
is
too
hot
to
hold,
you
are
not
getting
enough
water
flow
through
the
system.
Once
this
is
determined
look
for
the
cause.
The
best
place
to
start
is
the
over-the-side
through-hull,
if
your
boat
has
this.
Some
of
the
newer
boats
discharge
into
the
engine
exhaust
tube
or
beneath
the
swim
platform.
If
you
can,
check
the
water
discharge
flow.
Is
the
stream
discharging
with
its
usual
volume, simply dribbling, or perhaps stopped altogether?