On Sat, 5 Jun 2021 20:50:47 -0700, Bob F wrote:
The pump could be running all the time if it cannot get up to the cutoff
pressure. This could cause it to overheat because water FLOW is the only
thing cooling it much, and can certainly soften plastic pipe parts. If
it can't pump, the motor energy heats the water in the pump.

This is probably what made the plastic plug pop out without stripping.

The pump could be wearing out, and just can't get to cutoff pressure
anymore.

I think it's not getting to cutoff pressure because I measured it more
closely and it took less than five minutes to go from 20psi to 52psi
but the pump wouldn't shut off.

Once off, the pressure remains for hours (overnight is no problem but half a
day with water use it what it took so it was only two manual pressure cycles
for the whole day today, with showers and washing dishes included).


The black metal plug will rust. Galvanized less so, and brass not at all.


Is this pump one of those that turns off based on low flow, not
pressure. The flow sensor goes out on these, which will result in
continuous running. I recently pick up a slightly used grundfos MQ3-45B,
and discovered this while researching the use of it.

I think I found the source of the hissing which seems to be an air flow on
the pipe that connects to the bottom of the pressure switch. That pipe I
thought might contain water since it comes off the top of the pump but it
likely contains air. It seems to be the pressure that the switch senses.

It's way down at the floor level only an inch off the concrete so it's hard
to tell but I can put my hand there and feel a slight flow of air even as I
can't pinpoint the hissing due to the pump noise (it doesn't hiss with the
pump off).

What I might do tomorrow is buy a new pressure switch and see how that pipe
connects to it. Or, I may just tighten up the pipe fittings. I don't know
how these fail so I don't know what is the most likely to be successful.

I can post pictures but I have to sign up for imagur first I think.