Submersible pump failure in cistern

[bkwood]

Here is a brief and concise history (hopefully) of my cistern and pumps. Cistern holds approx. 1500 gal. Water ht. in cistern- 42 in. Elevation from cistern to house approx. 100 ft. Length of 1 1/4" pipe- 1000 ft.
1st pump - Sta-rite 3/4 hp, 2 wire, mounted horizontal, pumped great from 1980 to 2010. All the household water for 3 people ( 365 days/yr) plus pumped countless thousands of gallons for cattle watering trough.
2nd pump - Myers "Rustler" 3/4 hp , 2 wire,cat. # 2NFL72-12-P4 with a Pentek motor. Failed this year after only having to pump water for the house approx. 20 days/year (house now used by daughter as 2nd home). This pump was installed vertically in cistern. A hole was created in concrete bottom of cistern with pump inlet about 4" above bottom. This was done because retailer couldn't assure me that pump was rated for horizontal application.
At this point I have not disassembled pump to try and determine the cause of failure. The last time pump ran it was making horrible screeching noise for about 20 seconds before shutting down.
I would like recommendations for a new pump as I am concerned about premature failure occurring again. The details about the vertical mounting were included because after reading many posts about submersible pumps I became aware of cooling problems. The setup I have with the motor mounted in the concrete floor shouldn't have caused a problem, correct ?? I mean temp of water and concrete probably never gets above 55.
Any thoughts would be greatly appreciated.

 

[Craigpump]

If I'm reading this correctly, the motor is in a sump of some type in the floor of the cistern, which means the water surrounding the pump is not being exchanged, it just sits there taking on more heat. You really need to have water flow across the motor or have a big enough body of water to take the heat in order to have proper cooling.

I would probably install the pump on an angle and put a flow inducer sleeve over it to ensure it gets proper cooling.

Pentair ( Berkeley, Sta Rite, Myers) has had some issues with their pumps, I don't know if they're trying new engineering or backing some of the quality out or both... I personally like Grundfos pumps, but I'm not sure you can find them online.

 

[Sponsor]

 

[Reach4]

Suppose you made a flow inducer with 4 inch pipe. Then at the bottom, have big notches like a castle nut, for the water to flow into the bottom, and up past the motor to the pump intake. That way you could keep your pump vertical, and still get the cooling flow.

 

[Valveman]

A flow inducer or shroud is very important in a cistern pump. It won't hurt anything to have it lay on its side, but you do need a shroud or flow inducer. And even though the shroud would make it draw from the bottom, you can't stand the pump up or you will not be able to access the water below the pump intake. So you won't be able to get the last couple feet of water out of the tank if needed. The pump will still lose prime when the water level is below the shroud, as they are not air tight on the top.

Edit PS

The way you have that pump installed it is not getting any cooling past the motor. A shroud will fix that. But you also need to make sure the pressure tank is not waterlogged, because the cycling will also take a pump out in a short time.

 

[bkwood]

Thanks for all replies. I believe I will go back to a horizontal install but with a flow inducer even though my first pump lasted many years without one. I did read an old post by Ballvalve which stated horizontal mounting is a bad idea, shortens life of pump. From most of your responses I gather you don't agree?

 

[Reach4]

Most 4 inch submersible pump makers say horizontal is OK. Click Inbox.

You might be able to find whether it was the motor or pump end that failed. The ends are generally interchangeable and you see the pieces sold separately. Or you might want to figure out which part failed because you are curious.

 

[Ballvalve]

Why not buy a cistern pump? They are now available - water is picked up at the bottom and flows over the motor. Sort of an upside down submersible. And I still don't see a kingsbury thrust bearing working correctly horizontally. Or build your flow sleeve - a royal PITA in my un-humble opinion.

 

[PumpMd]

I guess it's that ceramic bearing you were talking about craigpump?

I would've never changed a thing since the first pump lasted 30yrs that way but could it have lasted longer with a flow sleeve on first pump? Sounded like you needed it on the 2nd pump install


It can also be what valveman said "But you also need to make sure the pressure tank is not waterlogged, because the Rapid Cycling will also take a pump out in a short time".

 

[Valveman]

Why not buy a cistern pump? They are now available - water is picked up at the bottom and flows over the motor. Sort of an upside down submersible. And I still don't see a kingsbury thrust bearing working correctly horizontally. Or build your flow sleeve - a royal PITA in my un-humble opinion.

A Kingsbury thrust bearing doesn't know what position it is in. It only knows what direction the force from the pump is coming from. There is not enough room in there for the thrust plates to fall when the pump is off. And when the pump is running the force from the pump is always pushing the right direction on the bearing. So horizontal installation doesn't hurt the pump as long as there is some pressure for the pump to push against. The same pressure needs to be there even in a vertical installation to keep the pump from upthrusting.

If you use the thin wall 100#, 4" pipe a shroud is easy to make. Thicker and stiffer pipe not so much.

 

[Valveman]

But also make sure the pump is not cycling on and off while you are using water. I talked to a pump installer today who was working on another pump installers job. The first installer had used a 1HP, 20 GPM pump with a 20 gallon size tank (only holds 5 gallons of water). The customer has burned up three pumps in three years from all the cycling. The tank was not waterlogged. The small tank without a CSV just caused more cycling than the pump can survive.

 

[PumpMd]

Pump installer was short cycling the pump on a 1hp 20gpm pump with a 20gal tank. We only use 20gal tanks on 1/2-3/4hp 10gpm pumps.

 

[Valveman]

Pump installer was short cycling the pump on a 1hp 20gpm pump with a 20gal tank. We only use 20gal tanks on 1/2-3/4hp 10gpm pumps.

A 20 gallon size tank (5 gallon draw) is still short cycling a 10 GPM pump. A 1/2 or 3/4 pump can just survive the abuse for longer than a 1HP or larger.

 

[PumpMd]

When you got pumps lasting 30yrs on average, do you really need a WX-250 tank, to get the proper drawdown on our 1/2-3/4hp 10gpm pumps?

 

[Craigpump]

When you got pumps lasting 30yrs on average, do you really need a WX-250 tank, to get the proper drawdown on our 1/2-3/4hp 10gpm pumps?

IF they're lasting that long on a 202, think how long they would last pumping into the proper sized tank!

 

[PumpMd]

I said the same thing to Valveman when I first got on this site. We use a 33gal tank on 1hp 10gpm pumps, 15gpm uses a 44gal tank, and 20+ gets 62gal or larger but it never takes us more than one tank to get long life on Residential Pump Systems.


We will install any size tank you want and recommend larger tanks as long as the customer has the money to do so but they usually don't and the smaller tank gets installed. This is how I get my research on pump systems and why I challenged the 26gal drawdown vs a 9.7gal drawdown on my two pump systems with Normal Cycling (10gpm)&(5gpm). I know it should be the bigger tank that wins but from what I have seen, I don't think it matters on non to light water users.

 

[Valveman]

I don't think it matters on non to light water users.

There is the key to why your systems last while others do not. You can get by with a lot of things with a house that only uses 300 gallons per day. But just turn on a garden hose to fill a pool or any real water use and cycling will quickly destroy a pump, even with a so called "properly sized tank". I hear from so many people who went through "three pumps in tree years" or similar stories that it is impossible to deny how destructive cycling is for pumps.

 

[PumpMd]

No, we don't have pools in Oklahoma...look up Edmond,ok on google earth and look at those pools on well water. My uncle has a big above ground pool on his well(15,000gals).

 

[PumpMd]

This is a good example: This one had a big underground pool and they did tons of outside watering on a 2005 CP Subdrive75 All SS Myers with Franklin Motor. Thrust Bearing out in 11yrs.

 

[Valveman]

This is a good example: This one had a big underground pool and they did tons of outside watering on a 2005 CP Subdrive75 All SS Myers with Franklin Motor. Thrust Bearing out in 11yrs.

That is pretty amazing for a pump/motor to last 11 years on a Subdrive. It was either too slow of a start from the Subdrive and/or the lack of a motor shroud that caused the thrust bearing to fail. But that one doesn't really count for how much cycling a pump can withstand, because the Subdrive is similar to the CSV as it is a constant pressure control and doesn't let the pump cycle on and off when using water for filling pools and such.

 

[PumpMd]

10yrs - 15yrs is about the average on what you will see on continuous duty and I can match that or better with less than a one minute runtime the traditional way.

Today I came across another pump system that works only a sprinkler system in a neighborhood so it turns off/on few times and has the bearing failing because sometimes it runs fine and others times it will have locked rotor amps. The pump was a Goulds on a Franklin Motor dated 2004.

I was able to acquire both pumps for breaking them down.

I think this is why Franklin went with the new tri-seal so little amount of backpressure is being applied to the thrust bearing. I am interested in seeing how they hold up in the field.