On 14 Aug 2018 00:54:22 GMT, trader_4 wrote:

The pressure sensor is the pressure control switch that you
previously called a relay. It has a water pipe connection on it.

I see the water pipe that someone mentioned, where it's also a relay based
on all those contacts visible on top.

I guess it surprises me that the front of the pump where the impeller must
be is "pressurized" since that's where the metal tube is coming out of.

The pump must have an EXCELLENT seal to hold that much pressure for so long
without leaking past 75PSI at any time I've ever looked.

Those two nuts adjust the cut-in and cut-out pressures.

That's good to know as I didn't know what exactly they adjusted.

Now that you described the whole setup, I see why you're calling
it a booster pump.

The pump appears to have only one purpose, which is to boost the water
pressure of the bladder from ambient pressure to about 75 psi.

I've seen these bladders everywhere where I live, so, they're pretty common
(every single home has one).

It's odd that someone said the "water tank" is pressurized, as that would
be astoundingly crazy to pressurize a 10,000 gallon set of tanks when all
you need to do is pressurize these little 4-foot tall bladder tanks.