On Thu, 26 Jan 2006 12:22:02 +1100, "David Flew"
wrote:


Not a bad idea to have a 'basket' over the pumps and float switch.
Also two pumps running off one float switch gives some redundancy.

IMHO the best way to go is a float switch and two small pumps, then
higher up above normal bilge water levels another float switch and
much larger pump. Ideally run each off different batteries.

cheers,
Pete.

I agree about the basket, if you have enough space. I don't, and mesh which
is small enough to protect the pump from debris soon blocks up with gunge.

A strainer over the pump and switch made of 5mm sq stainless mesh
should do (I have a bird feeder made from the stuff)

The Johnson float switch has an in-build strainer, so it's OK, and I just
have to regularly flush the bilges and be careful about housekeeping when
I'm doing carpentry on board ...

I've doubts that having two pumps off the one float switch makes things more
reliable. If either jambs, it would blow the fuse .... If you have
separate fuses for the two pumps, you still need a larger common fuse to
protect the switch and wiring.

I'd have two fused lines each feeding one pump +ve, then the -ves from
the pumps connected together and going to the float switch and back to
battery -ve. The on/auto switch would just go in parallel with the
float switch.

Also it seems the 1000 gph pumps seem to use the same casing as a
500gph pump, but cost almost twice as much. So for the price of some
extra hose and an extra outlet you can have 2 500gph pumps instead of
a single 1000gph one.

IME the pumps themselves fail in other ways rather than just jamming,
on my previous one the shaft snapped. So in that case 2 pumps would be
much better than one. Even if one gets partially blocked, the other
will work and lessen the rate the battery is flattened.

Maybe a straw poll of bilge pump/float switch failures would be
useful, can anyone else comment?

cheers,
Pete.

David