Pump has stopped....what now?

Defgufman

LifeTime Supporter
Mar 13, 2015
584
Savannah GA
Hi all, I have pentair sf-n1-3/4a pump that is 2 years 5 months old. Today I noticed the pressure was 0 and the motor was hot to the touch, but not pumping or even making a sound. My question is would you replace with the same or look for something different? Also can I just change out the motor and is that the best choice? Last, would you go up in HP if it were your pool? Thanks for the help.....
 

Defgufman

LifeTime Supporter
Mar 13, 2015
584
Savannah GA
Update if it helps- it seems to be a heat issue. If I wait for about an hour it will come on again but only for about 15 minutes before shutting down again. The Polaris keeps running even after the pump stops. Also, the pump stops even if Polaris isn't running.
 

kadavis

TFP Guide
In The Industry
Apr 5, 2015
1,651
tucson, arizona
That is the Pentair Superflo pump. It has a total hp of .93. Seeing that your pool is less than 14000 gal. and you have a sand dollar filter this is probably the right size pump. If you go with a larger motor you will also have to go with a larger impeller to increase the flow. When the pump comes back on is it primed and running at usual pressure?
 

JamesW

TFP Expert
Mar 2, 2011
22,038
Might be a problem with the voltage. With both pumps on, the voltage might be dropping too much.

If you're comfortable measuring voltage, check voltage with the pumps both off, then with main pump on and then with both pumps on.

You can also check amps of each pump to see if one if pulling too many amps.
 

Defgufman

LifeTime Supporter
Mar 13, 2015
584
Savannah GA
This is strange though that it would be a voltage all of the sudden. Nothing has changed for the last few years. I'll post pictures in a minute. Where I stand now is the pump seems to run fine by itself. I ran it for 5 hours last night without a problem. If I turn on the Polaris it runs for about 15 minutes then the main pump stops, but Polaris keeps going. This is especially odd since usually Polaris won't if the pump is not running.
 

JamesW

TFP Expert
Mar 2, 2011
22,038
The Polaris switch gets its power from the load side of the pool pump switch so that it can only run when the pool pump runs.

I suspect that the main pump motor is beginning to fail from bad windings or a bad capacitor. The capacitor can be replaced if necessary.

I also suspect that the wiring connections might be corroded. With corroded connections, the voltage can drop too much and cause the motor to overheat.

When wiring is not under load, the voltage at the pump will be the same as at the panel.

However, when any load is put on the wiring, the voltage will go down some.

How much the voltage drops depends on the total resistance of the wiring and the load in amps.

With only the pool pump on, the voltage is probably high enough to make the pump run.

When you turn on the Polaris pump, you double the load in amps and double the voltage drop.

Low voltage causes the motor to run at higher amps and overheat.

I suspect that the wire connections slowly corroded over time creating more and more resistance.

I would start by checking amps and voltages. Then check wire connections and switches.

Switches eventually fail. As they age, they can create excessive resistance.
 

JamesW

TFP Expert
Mar 2, 2011
22,038
I suspect that there might be at least two issues combining to cause the problem.

Since the pump works with the Polaris off, that points to a voltage issue. I suspect that when both pumps are on, the voltage goes below 220.

I think that there could also be a problem with the pump. It could be a weak capacitor. I don't think that the capacitor has completely failed because the pump still starts.

It might be the windings going bad.

You might find that a new capacitor makes the pump work. It might be that the undervoltage is tolerable with a good capacitor.

I would start with a new capacitor. Then check volts and amps of both pumps while both pumps are on.