Salt Cell Failed? Low Salt and High Temperature Readings

[gkw4815]

Well, I've been pretty happy with my Pureline SWG until this week...it has just started shutting down on Low Salt (after running for a few minutes once switched on and presumably generating chlorine, based on the appearance of bubbles at the pool jets prior to shutdown).

I checked salt levels with the TFLPool Kits salt kit and with the AquaChek strips that came with the SWG - both were in agreement at ~2900-3000ppm.

I added 120 lbs of pool salt and ran the pump overnight, now I'm getting ~4000ppm with the AquaChek strips. But the SWG behavior is unchanged - still shuts down on Low Salt after a few minutes. Cycling through the menu, I see it's reading 2000ppm instantaneous salt and a very high water temperature of around 120 degrees (vs actual of 80 degrees per Aqualink). In the past, the cell temperature readings were in line with the Aqualink readings. Amps and volts are normal. I checked resistance across the temperature sensor pins and got 3750 ohms (in line with 120 degrees).

The cell only has 1000-1500 hours on it ("check cell" light flashes every 500 hours and has only flashed twice). I've never observed any scale or build-up on the plates, and have never cleaned them with muriatic acid or vinegar. I tried scraping them off with zip ties this morning but nothing came off. My calcium hardness has always tested in the 250-300ppm range.

I'll be calling InyoPools today to see what they suggest, but thought I'd check with the TFP community as well. Unfortunately the system is about 1 month out of warranty, but if my cell has failed prematurely I hope they'd at least offer a discount on a replacement.

 

[mas985]

The cell internal temperature sensor has probably failed. If the sensor reads too high and the current remains the same, the unit will report a salt level that is too low.

Check with Inyo first to see if they will honor the warranty.

But if not, you can replace the sensor with a 10k resistor and see if that fixes the problem. I did this with one of my cells but I am not sure you can get to the temperature sensor leads in the back of the Purline cell like you can with the Hayward.

 

[gkw4815]

Finally an update...

The high temperature readings got higher and higher until they were reading 143 degrees F and the salt cell shut down on a "Hot" error message.

InyoPools was useless with getting this resolved. They suggested I buy a whole new cell, even though they no longer offer one on their website, and didn't offer any sort of discount as a goodwill gesture. I won't be doing business with them again.

I ended up doing as mas985 suggested and popping the cover off the cell to expose the wires leading to the failed temp sensor. Spliced in a 10k ohm resistor and cell is working again, will read 77 degrees F until the day it dies.

I don't regret buying a saltwater generator but I do regret buying a Pureline unit. Go with the Circupool RJ60 with the long warranty...

 

[Mdragger88]

I have a pureline T15 replacement cell - coupled with a very old aquarite. On a 26/27k gal pool
@mas985 this is good info as I aim to keep my hodgepodge undersized system functioning as long as possible. My cell is a little over a year old & I calculate about 1400 hours into its life. It has a 2 year warranty.
It has already paid for itself in fc production compared to bleach so I have no complaints thus far. I had hoped they would go ahead & warranty it in a case such as yours though with low hours & right on the edge of the warranty window. So that’s a little disappointing.

 

[mas985]

Here is another way to extend the life of a T-15 cell:

Failing T-15 SWG Cell Experiment

I am currently on my 3rd T-15 SWG cell for an 18 year old pool. The 1st cell lasted about 9 years and the 2nd about 4 years and just passed year 4 on the 3rd cell. I thought it might be useful to document this cell's behavior as it is going through the last stages of useful life. As time goes...

www.troublefreepool.com

 

[gkw4815]

Much to my own surprise, I have one more update to share...

Over two months after I asked InyoPools about a discounted cell replacement, they replied back to me with instructions on how to force the salt system to accept inputs from an alternate thermistor. The instructions were in broken English, making me think they were sent directly from the Chinese manufacturer, but they were easy to follow:

1) Replace standard flow switch with a combination flow switch + temperature probe (which InyoPools sent me at no charge).
2) Open Pureline control box and locate K1 and K4 sets of three pins on the circuit board. For both of these, the right two pins are connected via a jumper.
3) Move both K1 and K4 jumpers to the left, so they connect the left and center pins.

This alternate jumper configuration instructs the control box to accept temperature readings from the combination flow switch + temperature probe and ignore the thermistor that is integrated into the salt cell. All is working well now.

Not sure how common salt cell thermistor failures are, but this experience has me wondering why most salt systems integrate the thermistor in a non-replaceable fashion into the expensive salt cell, rather than into the cheap flow switch, by default...