[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Problems with Fluval 304 -- or The Matter with Clatter

Diana Berberich has a noise Fluval 304, replaced all the
parts in the impeller assembly and it still has a clatter. 
What's the matter?

I have had similar problems with Marineland powerheads. 
Within a the warranty period, Marineland will send you a
new rotor.  If that doesn't work, they will send, you
guessed it, another rotor.  If that doesn't work, they will
send a new powerhead.  Or so has been my experience.

These two-pole, permanent magnet rotor, AC motors are
extraordinarily simple.  In motors of this type, people
often say there is only one moving part, meaning the
magnetic rotor, which spins within a "rotating"
electromagnetic field generated by a pair of coils housed
around the rotor (usually sealed in epoxy or some other
potting material).  If the rotor is the only moving part
and it ain't rubbing, what else could possibly make the
clatter?  Well, probably the second moving part that they
all have.

The common culprit on Marineland powerheads is the
water-vane wheel, which is the small set of blades that
actually spin the water, forcing it through the powerhead
or pump.  These wheels are not fixed to the rotor shaft but
can rotate freely about 225 degrees or about 3/4 of a turn.
 If these wheels are just a tad too loose, they will cause
the pump or powerhead to clatter.

Old rotors can have wheels that have worn loose.  This is
one reason most powerhead manufacturers forbid using on/off
cycling timers (so-called wave makers) on their powerheads;
it promotes an early end of quiet life for the rotor wheel.

*But new rotors can have wheels that are too loose,*
although the rate of occurrence seems to vary by
manufacturer.  In my small experience, Marineland has a
high probability and Eheim an extremely low one.  (How many
Marinelanders say their Magnum is quiet vs how many

Other factors that can cause a clatter: worn or poorly
fitting bearings or misaligned bearing seats.  But I think
this is a rather rare reason for pump clatter.  Bearings
can be replaced if they are at fault but seat alignment can
be harder or easier to deal with.  It can be harder because
the seat alignment is generally fixed by the manufacture of
the pump housing.  But it can be easier because, with some,
a little push here, a little realignment pressure there and
you can help to quiet a noisy pump -- but only if bearing
seat alignment is the culprit in the first place.

[Just FYI: The purpose of the wheels being able to rotate
just so many degrees and then no farther is that is
prevents, most of the time, the tendency for the AC motor
rotors to lock-up when turned on rather than to rotate.  AC
motors don't care which way they turn and don't even want
to turn at all without some help at start up.  The "free"
wheel makes turning one way easier than the other.]

I suspect that, with enough rotors, you can have a quiet
Fluval.  Has your warranty expired?  :-\

Scott H.

Do you Yahoo!?
Y! Web Hosting - Let the expert host your web site