False low salt reading (IC-40) - Flow sensor changed twice.

[LanceC]

Hi Everyone,

My predicament: IC-40 only about 3 years old. It is big for my pool, so duty cycle is low. Only runs at 45-50% in summer. Started getting low salt reading. Cell is clean and had very low deposit. Salt is fine by mine and pool store verification. Salt is about 3800. Cell is reporting 1300, depending on water temp. Current water temp is 81. Changed flow switch with amazon cheapo (4-wire). My cell is 3 wire. Worked for a day or two before reporting low salt again. Replaced with Pentair flow switch (3-wire), and no go. Low salt from the install.

Verified thermistor in flow switch seems good...holding the MORE button on the cell, then pressing more once flashing, shows 80% which equates to 76-85 F which is correct.

Have done the basics like turned everything off, reset breakers, reset EasyTouch panel. Voltage from SWG transformer is 240v into relay. Have unplugged cell, restarted system, turned off, plugged back in, restart.

I understand the flow switch is the most common culprit in this scenario. Does not seem to be my problem.

Where is the microcontroller that makes the calculation for the salinity? On the SWG mini-PCB?

Any other thoughts?

General Info
Phoenix area
11k gallons
EasyTouch
IC-40 (originally was IC-20)
-part# 520555 07/28/2021

Thank you,
Lance

 

[TinFoilHat]

Have you pulled the cell to look for calcium buildup on the plates? Here in the Phx metro area where you will run it 9 months of the year or more, based on water temp, you have probably reached the end of it's life. They are generally rated for 10000 hours of usage and you could have easily gotten there in three years.

 

[Jimrahbe]

Lance,

I assume the cell is clean..

The thermistor, in the flow switch, is just there to compensate for the water temperature.. The cell use the water temperature when it tries to calculate the salinity.

If the water temp is correct, then the problem has to be inside the cell.

I suggest that you disconnect the thermistor from the cell, by cutting or disconnecting the White wire from the Flow Switch Assembly.

This will force the cell to use a fixed resistor inside the cell. If the salinity is still way off, then the cell is bad.

Thanks,

Jim R.

 

[LanceC]

Have you pulled the cell to look for calcium buildup on the plates? Here in the Phx metro area where you will run it 9 months of the year or more, based on water temp, you have probably reached the end of it's life. They are generally rated for 10000 hours of usage and you could have easily gotten there in three years.

Hi,

Yes, it is clean and I cleaned it a few months ago. It has not accumulated much buildup over the 3 years(I check it about quarterly but do not always clean it due to low buildup). Obviously does not run at all during our winter few months when water temp is very low 50's and as it is oversized, it only runs about 20% duty cycle outside the 4 major summer months, and only runs at 40-50% duty cycle during summer.

You may be correct, it is possible, but it would surprise me due to the very low duty cycle this unit runs.

Thank you,
Lance

 

[TinFoilHat]

If you clean it with acid and it's been done a few times that will also deplete the plates. The best way to clean is with a non-sharp mechanical means and then diluted vinegar which is easier on the cell but still depletes them a bit.

 

[LanceC]

Lance,

I assume the cell is clean..

The thermistor, in the flow switch, is just there to compensate for the water temperature.. The cell use the water temperature when it tries to calculate the salinity.

If the water temp is correct, then the problem has to be inside the cell.

I suggest that you disconnect the thermistor from the cell, by cutting or disconnecting the White wire from the Flow Switch Assembly.

This will force the cell to use a fixed resistor inside the cell. If the salinity is still way off, then the cell is bad.

Thanks,

Jim R.

Hi Jim,

Yep, cell is clean. Since it is oversized, it gets much less buildup compared the IC-20 it replaced. I rarely need to clean it due to buildup.

Can you confirm the "cut the white" is correct for the post 2018 3 wire IC-40? Most notes I have found seem to be discussing the pre-2018 4-wire IC-40.

Thank you,
Lance

 

[Jimrahbe]

Lance,

The Red and Black wires go to the Flow Switch.. That just leaves the White wire, which also uses the Black wire.. Unless you have different colors???
Coming from the cell, you should have three wires.. Red, Black and White.. What do you have??

You don't have to cut it, you can just disconnect it and see what happens.. If you disconnect the White wire, and the Flow Switch still works, then you will know for sure that the White is going to the thermistor.

Thanks,

Jim R.

 

[LanceC]

Lance,

The Red and Black wires go to the Flow Switch.. That just leaves the White wire, which also uses the Black wire.. Unless you have different colors???
Coming from the cell, you should have three wires.. Red, Black and White.. What do you have??

You don't have to cut it, you can just disconnect it and see what happens.. If you disconnect the White wire, and the Flow Switch still works, then you will know for sure that the White is going to the thermistor.

Thanks,

Jim R.

Jim,

Correct. B/R/W wires only. I have disconnected the white, restarted pump, cell cycles through its startup and lands on..... Low Salt.

So, whether thermistor is hooked up (and reading temp correctly) or disconnected, the salt level is still not calculating correctly.

Thanks,
Lance

 

[LanceC]

Have you pulled the cell to look for calcium buildup on the plates? Here in the Phx metro area where you will run it 9 months of the year or more, based on water temp, you have probably reached the end of it's life. They are generally rated for 10000 hours of usage and you could have easily gotten there in three years.

Internal diagnostic reports 2,000 hours....

 

[Jimrahbe]

Lance,

In my mind the hours used (or left) is pretty useless info... It only looks at how many hours the cell was producing chlorine.. It can't tell anything about the other 2,000 possible failures that can happen...

Sorry for your loss,

I guess you could test the DC voltage leaving the Surge Card.. Test between the large Red and Black wires, with the cell connected and see if you get about 35 to 40 volts DC.. I think it can go as low as 28 VDC.. I would assume if this voltage was so low that it would effect the salt readings, the cell would not light up at all, but worth testing before buying a new cell.

Thanks,

Jim R.

 

[LanceC]

Just confirming that I have 40VDC coming off of the surge card. Time to replace that salt cell. Thanks everyone for your guidance.