IC40 always reads low salt

[Rszimm]

I've got an IC40 on my 17k gallon pool (I know, a bit oversized). This season it seems to read low on the salt. I first noticed it about a month ago when the red LOW SALT light came on. The cell was reading about 2400. I tested with a Taylor liquid salt test kit and got 3400. I pulled the cell and acid cleaned it and put it back in. For a few days it read around 3200, then started drifting down and is now reading around 2600 and the red light is on again. Again I tested with the Taylor kit, and on the 17th drop again got the brick red color (3400 salt level).

It's less than 2 years old. Here's a video of what happens when I press the diagnostic button (

). Notice that NO lights come on indicating how many hours the cell has run. What does that mean?

Is it possible my test kit is faulty? I know my CYA is a bit high (around 60) and my calcium is also high (around 650, but it's pretty impossible to keep this low in Tucson as the water comes out of the tap at like 300).

I'd like to diagnose this relatively quickly if you think the cell might be at fault as the warranty on the cell is 2 years, and I'm approaching that (I think July will be 2 year mark)

 

[mknauss]

Try this to diagnose a flow switch thermister failure.

Pressing and holding the “More” button launches the System Status Mode. When the lights finish scrolling, the percent lights indicate hours of usage in 1,000s. For example, if the 40% light lights, that indicates 4,000 hours.

Version 3.1 on adds the ability to determine system temperature. Pressing the “More” button after the display shows 1,000s of hours of usage, will show temperature as follows:

Lights…………….....………Temperature
No LEDs………….…..………Below 30F
40%..........................36 to 45F
40% and 60%............46 to 55F
60%..........................56 to 65F
60% and 80%............66 to 75F
80%.........................76 to 85F
80 and 100%............86 to 95F
100%.......................96 to 99F
100% blinking……..….over 99F
All LEDs blinking……...Sensor bad

Hold down the MORE button on cell for 6sec and watch the Cold Water/PWR light if it goes RED that tells you the temp sensor is bad and you need to swap out the flow switch/temp sensor (520736). If it doesn’t turn RED it could still be bad but it just hasn’t failed completely and then you need to make sure salt level in the pool is 3500 or above if it is swap flow switch/temp sensor (520736)

 

[Jimrahbe]

R,

Since youe cell is under warranty it makes no sense to me for you to do anything but call your pool builder, or Pentair, and have them come fix it... I too suspect that the thermister in your flow switch is bad... It is a very common failure and if it happens after your warranty is over, it is a very easy DIY fix..

Thanks,

Jim R.

 

[Rszimm]

So if NO lights show up for the hours of usage that means I've got less than 2000 hours on the cell?

Here's a video of doing the temp sensor check. Seems to read 86 to 95, which is a tad high (it's about 83 by the controller temp), but pretty close.

To do the temp check I pressed MORE for 3 seconds to get into the hour meter, then pressed it again and it showed me the temp. (is that correct). I tried pressing it for 6 solid seconds (also shown in the video), but it didn't seem to do anything special.

 

[Rszimm]

Thanks for your help guys. I'll give Pentair a call. Would a thermister cause a low salt reading even though the cell seems to think the temp is correct (well, a couple of degrees high)?

 

[JamesW]

Based on the test, the cell is reading the temperature incorrectly (possibly as high as 95 degrees). That will cause the salinity to read lower than actual.

The thermistor is known to be unreliable.

Once it begins to fail, the temperature reading can become erratic and fluctuate over time.

If it's warranty, just let them fix it.

If it's out of warranty, I would just install an external temperature sensor and use that instead of the one in the switch.

You would just disconnect the thermistor in the switch and connect to the external thermistor.

Pentair 520272

 

[Yorker]

Hey Rszimm ... any update from Pentair yet?

 

[Rszimm]

A guy came by from Pentair this morning and swapped out the flow switch. Reading 3200 currently (close to actual reading of 3400). Interesting that they didn’t just swap the cell, but whatever gets me up and running!

 

[Yorker]

Glad it's up and running. Our local Pentair warranty repair guy is coming on Wednesday. Our cell has been all over the place for about 4 months, sometinge 5500 salt readings when our Taylor drop tests at 3600, or low salt readings a couple of times. It registered Too Cold until the water was 70° at the end of March. Then just yesterday the water temp was 74 and it registered too cold again. It will be interesting what they say, our system is just over 1 year old. ... Fingers are crossed.