Short life spans for 1.5hp motor/pump

[JohnnyD]

I’m getting just 4-5 years out of my residential (irrigation) well pump. I have changed out 4 of them over the years. It is used just to water my lawn from May – September (Boston area), run 2 to 3 times per week. Current situation – Pump does not run, control box overload trips after ~20 seconds. I have swapped the Control Box with a new one that I have – same results. Voltage readings are in spec. Using a DVM and a VOM the resistance readings for the primary and starting windings are within specs. Wirings-to-ground are around 40K ohms. The expansion tank air pressure was in specs at the end of the last watering season. I do not recall excessive cycling of the pump when the irrigation system was on. Well is ~420’ deep in mostly ledge. Though I hoped my problem is above ground my assumption is that my motor is toast again.

Given the depth of the well and the labor to pull it up each time, I have replaced the motors and pumps together. Each time the motor leads appear fried where they enter the motor housing. I do not believe we are in an excessive lightning area (possible reason for the motor leads frying?).

Specs - 1.5hp Gould 10GS15412CL pump with CentriPro M154120-01 Motor. 220V single phase. Well-X-Trol WX250 tank. Franklin and CentriPro Control boxes.

Current guesstimate for replacing the pump and motor in my area is $2.2K – $2.5K. I had pulled the pump once by hand (with help) but nicked a wire which prompts me to let the pros do what they do. I would like to put in a 10+ year solution. Would folks have ideas on why I am going through motors so often and what I can do to have a longer-term solution?

Thank you

 

[Valveman]

Cycling on and off is what kills most pumps. I hear people say they don't have "excessive cycling" all the time. When I ask how often it does cycle, they say "Only maybe every 5 minutes or so". While a 5 minute cycle may not seem excessive, that is 288 cycles per day, and the pump won't last long. I know adding a Cycle Stop Valve to your system will stop the cycling and has been known to make pumps like yours last 30 years so far. If cycling is the problem adding a CSV is an easy fix. Cycling usually burns up the motor, strips the spline, or breaks the shaft. Although, cycling also causes the wire to chaff, as well as check valves, pressure switches, and even tank bladders to fail.

Having said that and guaranteeing the CSV to make the pump last longer, they have had problems with the Centripro motors. I see where they even list them as Gen1 or Gen2, depending on the date. I am thinking they need a Gen3. If I were you I would try a Franklin motor. Franklin pumps are not that good but I still think they have the best motor.

BTW, any short down the well is not good and if a new control box with proper voltage doesn't make it run the motor is out again as you suspect.

I would be glad to do an autopsy on any of the old pumps if you would like? Finding out what caused the last failure is the best way to prevent it from happening again.

 

[wpns]

If it's just for the irrigation system you may not need the pressure tank and pressure switch, just use the 'motor run' output of your irrigation controller to turn the pump on during the entire cycle.

 

[Valveman]

There are pros and cons to both the pump start relay and the pressure tank/pressure switch method.

With a pump start relay your pressure is determined by the size of the zone. Matching the size of the zones to the pump is important, as small zones will have high pressure and large zones will have low pressure. If the zones are sized properly the pump start relay works fairly well. One downside includes the problem that occurs when the gophers eat the wires to the zone valve, as the pump comes on but no sprinklers. Adding a 75 PSI pressure relief valve can save your pump from melting down when/if this occurs, which I see fairly often. The pump also starts with no pressure against it, causing a hard start for the pump and water hammer to the rest of the system.

With the old pressure tank/pressure switch method, you still had to match the size of the zones to the pump to keep the pump from cycling on/off to death. But when a Cycle Stop Valve is added to the pressure tank/pressure switch system you can match the sprinkler zones to the yard and not the pump. The CSV will not let the pump cycle as long as you are using more than 1 GPM. The CSV will maintain a constant pressure on any size zone. Starting the pump against pressure and keeping the irrigation system pressurized keeps water hammer from happening on pump start and when zones open and close. The CSV also eliminates water hammer on pump stop. Plus, the pressure tank/pressure switch/CSV system allows you to continue using a hose when/if needed, and even the hose will not cause the CSV system to cycle. You have everything you need to make this happen except the CSV1A.

 

[Riickk]

I'm ignorant about well pump systems, but burnt (overheated) wires?, suspicious. How far underground is the pump?... 400+ feet?
What gauge wire is being used to supply power to the pump?

 

[wpns]

Valveman is not wrong, which is why I have a pressure tank _and_ pump start relay, plus a Raspberry Pi watching water temperature and pressure, pump housing temperature, inflow and outflow to my storage, etc. And there are still unexplained failures, but at least I can see them and call for maintenance. 8*)

 

[wpns]

I'm ignorant about well pump systems, but burnt (overheated) wires?, suspicious. How far underground is the pump?... 400+ feet?
What gauge wire is being used to supply power to the pump?

Riickk is right, there's something else going on besides number of cycles, you need a better root cause analysis (possibly in addition to reducing your pump cycles by using a CSV or Master Pump relay).

Could be lightning strikes, could be low voltage causing high current, could be insufficient slack in the motor power leads causing them to abrade on the motor housing (assuming the plastic pipe stretches as you draw the well down), could be wire size or material, could be pump rotation during start/stop cycles abrading the wire against the wall of the bore (I've had this happen myself), could be any number of things.

Don't just replace the pump again and expect a different result.

 

[JohnnyD]

Thanks all for the feedback / replies. It will be a week or two before I engage a company to further the troubleshooting. I will report back with what I find.