Pump stops mid pump then restarts, pressure SW OK

[Cool Javelin]

I have a weird issue, I thought I had a bad pressure switch, but after replacing and checking the pressure, I found the pump would cycle once or twice OK, then it would stop before the pressure was reached, then after some minutes, it would restart and continue till the pressure cut off.

It is a 3 wire system with control box in garage, pump some 150' away, but only about 25' deep.

I have searched the web and cannot find any good 'theory of operation' for the control box. All I get is "here is how to hook it up." If someone can point me to a good place that has a schematic of the control box, and a good explanation of how the system works I like that. I do have experience with electrical wiring and engineering, but never thought about well pump systems.

Here is the symptom in more detail:

Pressure sw is a 40-60 (new.)
Open hose bib to lower pressure, at 40 the switch clicks, and the pump starts (as expected.)
During normal operation, I can hear the vibration of the pump throughout the house as a low hum (not unusual.)
Sometimes, before the pressure reaches 60, the pump will stop. There is no noise that I can tell.
After some time (maybe 1 - 2 minures) the pump will just start up again and continue till it reaches 60psi.

It seems the pump is louder then last week but that may be my imagination. That may be a clue.

The only diagnostic tools I have are 2 volt meters. I do not have a current probe.

After research for a bit, My thoughts are as follows (please help me to test these theories and suggest some I may have missed.)

Theory #1. The pump has a thermal protection in it, and it is over heating although I can't imagine it getting too hot when it is submerged in 50 degree water.

Theory #2. it has thermal protection, and the protection is failing.

Theory #3. the run capacitor is going bad. How would I test this? Is the run cap and start cap the same size? can I swap them to test them?

Theory #4: I see there is a relay in the control box that I assume switches from start mode to run mode. Maybe that relay is not switching and the pump is staying in start mode. Would the pump overheat in that case? How can I diagnose that? I have 2 volt meters

Thanks in advance for any help you might offer.

Mark.

 

[Reach4]

Check to see if the B to Y terminals out of the control box maintain 230 volts as the pressure is rising and goes to its early-stop time.

#1 and 2 make sense.

#3, run and start caps are not interchangeable. If you have a bad start cap, the motor won't start. Bad run cap, I think the pump runs anyway.

#4, I think the B to Y voltage would be affected.


I am not a pro. The Franklin AIM manual has good info including box schematics starting on page 53.

 

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[Cool Javelin]

Thanks Reach4: The lead to the Franklin AIM did help me understand what is happening.

Update:

I did not have the proper tools to really test the issue, but found my neighbor has one of those clamp-on current probes. (Man, I need to get me one of those.)

Checking the current on the red wire (the start winding,) I see the current come up right away, then drop to zero after 1/2 sec or so. This seems to be normal.

The current on the main winding is about 10.5A, and slowly drops to 9A. I know as motors heat up, they draw less current.

After about 3-4 minutes, the pump just stops, everything is quiet, no current draw, but voltages are all on the wires leading to the pump. I guess this would be expected if the thermal overload switch in the pump opened.

So, I guess I need a new pump. It is at least 14 years old. I have no idea when the previous owner replaced it before I bought the house.

I will get a new control box too.

Mark.

 

[Reach4]

The current on the main winding is about 10.5A, and slowly drops to 9A. I know as motors heat up, they draw less current.

The current also drops if the water level drops significantly (lower flow due to higher head) and drops even more if you run out of water. There are devices that take advantage of that to detect that you are out of water, and to shut down your pump for a while. While the pump runs without much water, an temperature sensor in the pump could shut you down for a while.

 

[Valveman]

Heat doesn't make the motor draw lower amps. Like Reach says the water level dropping and/or the pressure increasing is what lowers the amp draw. If the start cap and/or start relay was out, the overload would trip on start up. The fact that the pump is already up and running when the overload trips means the motor is bad. They only have so many start/stop cycles built in. The windings swell and grab the rotor when the motor heats up, which trips the overload. It doesn't matter how cool the water is, the overload heats up from high amperage. 14 years is double the average life, so your pump probably cycles half the average number of times. Eliminate the cycling and the pump will last much longer.

 

[Cool Javelin]

I have a good well saver, so start/stop cycles are minimized.

OK, I have this hair brained idea. I see I can get 2 wire 0.5HP pumps for about 2/3 or 3/4 the cost of a 3 wire setup. I guess it is because they don't have the added external control box.

Since I have 3 wires leading down the rabbit hole, I thought I might put two 115V 2-wire pumps down there. (My well casing is about 2 feet in diameter.) Put a Tee and check valves below the pitless and use one leg of the 220V for one pump, and the other leg for the other pump.

Then, only use one of the pumps. After 10 years or so, simply switch to the other leg and use the other pump when the first fails. (Actually, I would put in a switch and alternate between them once or twice a month or so to keep them alive.)

I have always been an overkill kind of personality, is this too much?

Thanks, Mark.

 

[Reach4]

I have searched the web and cannot find any good 'theory of operation' for the control box.

Theory of operation... there is a run winding, which sees the full AC. The start winding current is a little ahead of the power line voltage during start due to the start capacitor in series during the start. The phase difference creates the rotating field that gets the pump started.

Once the pump has started, a relay opens the path through the start cap. In a simple box, that is it. In some boxes there is a smaller non-electrolytic cap that maintains a smaller rotating field during run. Power efficiency is a bit better that way.

) Put a Tee and check valves below the pitless and use one leg of the 220V for one pump, and the other leg for the other pump.

You would either rely on the check valves built into the pumps, or put an additional check valve right above each pump and before the tee. No other check valves if using a precharged pressure tank.

I think you could do the same thing with 230 volt pumps.

 

[Valveman]

2 wire motors are fine. And as long as it is the same horsepower, you still only need one. Usually a 3 wire pump with a control box is the same price as a 2 wire pump that doesn't need a control box. But if you find a 2 wire for that much less I would go for it. The "well saver" doesn't minimize cycling, or your pump would have lasted longer. The "well saver" may shut the pump down if it rapid cycles, but won't stop it from cycling on/off while using water. Over time, even so called "normal cycling" will wear out the motor. No deeper than it is, save your money for the spare pump and get you a new one when the time comes. No sense in aging a spare if you don't have to.

In such a shallow well those 1HP, 33 GPM Hallmark pumps will work, and they are only like 150 bucks.