On 13 Aug 2018 18:08:55 GMT, trader_4 wrote:

IDK why you call it a pressure booster pump instead of just a pump.

Thanks for your helpful advice.

I agree with you. It's a pump. Specifically, it's a 1HP 3450RPM pump.
http://www.bild.me/bild.php?file=9787347pressure01.jpg

The job, AFAIK, is to boost the pressure coming out of the filled water
tanks, because, the tanks are comopletely full so the well pump (which is
500 feet deep) is working just fine.

Without the pressure pump, there is no water pressure inside the house.
http://www.bild.me/bild.php?file=9113867pressure02.jpg

The label, on the outside, says it's a "Jet Pump", whatever that means.
If I need to replace it, I am guessing I just need to match the bolts.

It sounds like it's a jet pump and the only one. Jet pumps differ from
a piston pump in that they can bring up water from depths that are lower
than the max lift of a piston pump, which I think is like ~28 ft?

In this case, the well has its own pump that is 500 feet deep.
There's nothing wrong with the well pump as the water tanks are full.

There's plenty of water in those tanks.
There's just no pressure when the pressure pump fails to turn on.

They use two pipes, one pushes water down the well to the other part
of the pump where a jet action picks up water and it comes back on
the other line.

I am sure this is a two-pump system.
1. There is a pump inside the well (deep down), and,
2. There is a pump outside the tanks (on the surface).

The pump deep down is working just fine as the water tanks are full.
There's plenty of water.

There's just no pressure.
The pressure comes from this pump.

Frame size, voltage, speed, hp and maybe if it's suited for a wet location,
etc if it's exposed.

It's in a shed. Nice and (reasonably) dry. Here is the label.
http://www.bild.me/bild.php?file=6757739pressure04.jpg
General Electric AC Motor Thermally Protected Jet Pump Motor
Mod: 5KC39QN1157AX HP: 1 HZ: 60 V: 115/230 PH: 1 RPM: 3450 CODE: L

I agree with you that I think the only spec that matters is:
http://www.bild.me/bild.php?file=2105511pressure05.jpg
a. The frame size - *where is the frame size listed?*
b. The voltage - this is running off of 110 it seems
c. The speed - this is 3450 rpm
d. The HP - this is 1 HP

The thing you're calling the relay is the pressure switch.

Ah. I didn't realize that relay was actually a pressure switch.
How on earth does it *measure* the pressure?

How can it sense the pressure from OUTSIDE the water supply?
This is a key question because the reason the pump isn't going on could
either be the pump is going bad - or - the pressure sensor is going bad.