> When you start restricting the output of the pump with a valve, Doesn't
> this make the pump motor work harder thereby shortening it's life and
> possibley increasing electrical usage.
Actually just the opposite Happens, David. I wish there was a simple way
to demonstrate this with a pond
pump and easily available items... but I
can't think of any. If you have a hair dryer, try turning it on in the
"air only" mode, and then completely block the air discharge with your
hand. You'll hear the moter speed increase, indicating that it is doing
LESS work. If you had a way to measure the input current, it would
decrease under the blocked condition. From physics, you might recall
that work is the result of moving a weight through a distance. When the
pump outlet is restricted, less weight moves through the same distance.
> Also if you have a 1/2 horse pump that is pumping 1200 gph and you only
> need 600<>800 gph. Seem to me that monthly elecrical bill wise it would
> be cheaper to buy (dirty word) a 1/4 <> 1/3 hp pump that draws less
This MAY be true, but depends on lots of efficiency-related factors in
the pump motor and centrifugal pump design. The bottom line is "how much
current does this pump draw when it is pumping water at this rate". If
you hold "this rate" constant, only then can you campare the current
drawn by pump A vs pump B.
Geez I wish spring would come... :)
"Is it true that the hours you spend on rec.ponds
don't count against your lifespan?"
Kellie Sisson Snider