On Wed, 4 Dec 2019 00:19:37 -0500, danny burstein
wrote:

(numbers very rough. I didn't have a tape measure...)

We've got a typical sump pit, more or less two feet in diameter
and three feet deep. The standard corrugated plastic deal
that kind of looks like an upside down garbage can.

There's a 3/4 or so horsepower (HP) submersible cast iron pump
sitting at the bottom with a float switch that has more or less
six inches of travel.

Earlier tonight the switch stayed "closed" (that is, "on")
despite there being no water flowing. Fortunately I heard
it before any damage to the pump.

I got to it, moved the float up and down a couple
of dozen times to free it, and things are ok for now. But it
got me thinking:

a: any suggestions for lubricant that would reduce the
chances of this happening again?
Fluid film?


b: and... that 3/4 HP is way more than needed most of
the time. Even in the worst of rains we could probably
manage with less than half that, and more typically
it's a 10 seconds on, two minutes off, kind of deal.

Install 2 small sump pumps - one 4 or 5 inches above the other. The
low pump does most of the work, but in heavy water conditions the
second pump takes the excess. This is ONE place where a check valve is
mandatory unless you use 2 outlets (which is not a bad idea - because
if the main discharge gets plugged, causing the sump to overfill, the
second pump has it's own outlet and can still work.

So... I was wondering if there's an automatic variable
output sump pump out there that anyone's heard of.

The way I envision it is that if the water is six inches
off the bottom, the pump would run at 0.1 HP. At ten
inches it would ramp up to 0.5. At 24 inches it would
switch to the full 1 HP output.

(Numbers for illustration).

So yeah, it would need multiple sensors or a funky
float arrangement or something.

I can visualize lots of ways of designing something
like this, but I was wondering if such a beast
was available off the shelf.

Thanks for any suggestions.

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