IC40 reading 1,000ppm lower than test, having problems maintaining FC level

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brucehenson

brucehenson

Gold Supporter
Nov 27, 2018
124
Taylors/SC
Five years in and still feel like a rookie.

I’ve been running my IC40 at 100% for 10 hours per day. This weekend the system issued a very low salt warning. Test confirmed salt is at 3,600. FC is falling slowly And is now at 5.0. CYA has fallen from 80 to 60. IC40 is 5 years old.
 
Bruce,

Sounds like you need a new flow switch assembly. Inside the flow switch assy is a thermistor that often goes bad and causes the cell to report the wrong salt level. It is a simple DIY repair.

Make sure you get a 3-wire flow switch as it will work on old or new cells. Do not get the old 4-wire version.

Thanks,

Jim R.
 
This forum pays off again!

Testing confirms your diagnosis (both of you) thank you. Two questions:
1) Is it advisable to purchase the Pentair part or is after market as effective? 3 wire of course!
2) Should I cut the green and/or the white wire while I wait for the replacement part?
 
Cut the white wire, added I gallon of 10% chlorine, and waiting on replacement part.
Thank you both.

Jim, I could not find the 3 wire version. They are all 4 wire with instructions on how to connect to 3 wire systems. Do you know where to get a 3 wire replacement? I am using Amazon but can change sources.
 

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mknauss said:
Inyopools has the 3 wire. For $208!! Wow.

Pool Guy Supply has the 4 wire aftermarket for $39. Are we sure the 4 wire will not work?
Click to expand...
The 3 wire flow switch can be used on older 4 wire cells. The 4 wire flow switch cannot be used on the new cells manufactured after September 2018.
 

Replacing Bad Temperature Sensor in the Flow Switch with a Separate Sensor.​

Pentair has the temperature sensor integrated with the Flow Switch. If the temperature sensor fails Pentair expects the entire Flow Switch assembly to be replaced. The temperature sensor in the Flow Switch is a standard 10K thermistor temperature sensor which can be used in place of the one in the flow switch.

Install the thermistor in the plumbing near the cell using a water temperature probe, like the one that comes with an EasyTouch. Drill a hole in the pipe, stick in the probe, and use a hose clamp to hold it in place.


600px-Temp_probe_hack.jpg



Then cut the green and white wires in the flow switch. Attach the two wires from the thermistor to the green and white wires going into the cell using Scotchlok UR2 connectors so you don't have to strip the wires. Just crush the button and the wires are connected. The two green and white wires coming from the switch will be left disconnected.

Newer Cells (after 2018)have a 3 wire system. The black wire is common. Just cut the white wire, attach one wire from the thermistor to the white wire, and one to the common black wire.



3 wire external thermistor.jpg
Now the cell sees the water temp from the new probe and not the thermistor in the flow switch.
 
That’s good reading, thanks James.

Jim, all of the 4 wire units have a wiring diagram for commenting to three wires. Although different from what I have. My IC40 is 3 wire and the green and white wires from the flow sensor were connected to the IC40 white wire. Red was connected to red, and black to black.

1686587163804.jpeg1686587163804.jpeg
 
Bruce,

We have seen a couple of cases where an OP has a 3 wire cell and installed a 4-wire flow switch and it did not work.

Allen has posted this, "The 3 wire flow switch can be used on older 4 wire cells. The 4 wire flow switch cannot be used on the new cells manufactured after September 2018." but not sure where he got it.. Calling @ajw22

Thanks,

Jim R.
 
Thanks Jim. Our pool was COMPLETED in Oct. of 2018, could go either way on the 3/4 wire change. Our IC40 is 3 wire (gray jacket) and the sensor is 4 wire (black jacket). I’ll just have to install as the diagram above shows connecting the green and blue to the IC40 black and see what happens.

I’ll keep you posted.
 

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The cold water cutoff must be measured by the cell and not the control system. This means that if I leave the white wire cut the cell will not be able to protect itself from cold water this fall.

Im going to have a 4 wire cell and a 4 wire switch. Wish me luck because I'm just confused at this point.
 

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