Pentair INTELLICHLOR Flow Switch Replacement

[JoyfulNoise]

So I thought I would share some pictures of what I did here so that there’s a reference to look at. Others have done this in the past, so there’s nothing new here.

Backstory

So at the beginning of the season I noticed that my IC salinity readout from my EasyTouch panel was quite a bit lower than the actual value from my K-1766 kit.



I removed the cell and looked at it but found no scale. I did a quick acid wash (I typically only use diluted MA, 5:1 with distilled water) and noted no bubbling so I did not let it soak. I replaced the cell and ran it but the salinity was still much lower than actual (by more than 800ppm). So I then ran the diagnostic mode to look at cell life and internal thermistor temperature (many thanks to JamesW for posting the diagnostic procedure info). Here is the procedure -

IntelliChlor Diagnostic Procedure

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

My cell life was only at 4,000 hours BUT my thermistor was showing an LED light at 100% which is a lot higher than the actual water temp. So clearly the thermistor was starting to go bad. However, because it was the beginning of the season, I knew the water was going to get warmer and the cell would function. I also had a busy summer and couldn’t devote the time to messing around with the pool. Over the last few weeks, my local weather has gotten chilly and my water temperature has gotten to the low 70’s. Because of this, the apparent salinity reading of the SWG moved into the VERY LOW SALT error range and my SWG stopped producing chlorine. Also, the diagnostic procedure showed a blinking 100% LED (FAILED thermistor) and all blinking LEDs. So the thermistor was shot at this point. I’m not ready to start jug dumping bleach, so I decided it was a time to fix the thermistor problem.

There are two options when the thermistor starts to go - (1) replace the flow switch assembly (Pentair P/N 520736) OR (2) install an external 10k thermistor and hook it up to the existing SWG wiring. Option #1 is the more expensive route as the Pentair replacement part is fairly expensive for what it actually is (a flow switch and thermistor). I found ther p/n online (Amazon) and paid around $100 for it but I did call around to local shops and ALL of them wanted over $200 for the part. So there’s a lot of markup to a part that probably costs a few dollars to make and is sold by the crate-full from the manufacturer to Pentair. Finding a simple in-pipe 10k thermistor is a lot cheaper (the Pentair air temperature thermistor will work) but it does require you to drill a hole in your plumbing and then “hack” that wiring into the SWG flow switch wiring. It’s not a lot of work but most people probably don’t want to do that. I have an extra air temperature thermistor that I can use if this flow switch replacement part fails prematurely (they have a habit of doing that).

So, here’s the part -



The flow switch assembly is fairly easy to replace and the instructions are written well enough. The kit comes with some 3M wire connectors that don’t require you to splice the end of the wire. Just simply insert similar colors into the connector and use a pair of needle-nose pliers to push the connector closed.

Here’s what the SWG looks like with the flow switch cover removed -



Just cut the wire (nearest the flow switch) and then unscrew the flow switch nut. It only takes a 1/4 turn of wrench to loosen the nut and then it can be backed out by hand the rest of the way. Here are the old and new parts side-by-side -



The old flow switch got a little mangled coming out because ther magnet got hung up but the new assembly went in fine. One can see a little bit of corrosion on the metal stem of the flow switch magnet and it’s not uncommon to have those stems fail and the magnet fall off thus causing a flow error. Honestly I think this part (flow switch and thermistor) can be much better engineered but I’m sure Pentair is just going with the lowest cost, commercial-off-the-shelf item they can find. Here’s the new flow switch assembly installed -







The nut on the new flow switch is about twice as thick as the old one which makes grabbing it with a wrench a lot easier. After putting everything back together, crimping the proper wires together and turning the system back on, I re-ran the diagnostic. This time I got the 60% and 80% LEDs to light up meaning the internal thermistor was reading a temperature between 66F and 75F. The water temp was 71F so that is correct. My salinity finally read closer to actual (actual salinity is 3400ppm) -



With the repair complete, my SWG is now running correctly and I’m free to be lazy and not jug-dump for another two months.....

Future Work - take the old thermistor and measure it’s output resistance at different temps to see how badly failed it is. If this repair only lasts a year or so (many report that these flow switch replacements fail sooner than the OEM part), then I’ll use my spare in-pipe thermistor as others have done.

 

[JamesW]

Good job. Thanks for the post.

One argument for the 10 k thermistor method is that you have to cut and splice the wires anyway. You would just cut the white and green wires and leave the red and black wires intact, which is actually trickier to do than cutting and splicing all 4. But, you could cut and splice all 4, but just reconnect the red and black back together.

So, the only extra work is to drill a hole in the plumbing and attach the thermistor with the clamp, which is about the same amount of work as removing and reinstalling the flow switch.

The 10k thermistor is cheaper and more reliable than the flow switch. If the flow switch ever failed due to the flow switch part, you could replace it with a cheap flow only switch.

The argument against the thermistor method is mostly that it's not a Pentair approved method and would probably violate the warranty. It might also affect the UL safety rating of the cell. So, I can't recommend it even though I think that it would probably perform better in the long term.

 

[JoyfulNoise]

I agree that the in-pipe thermistor is probably the better long term solution. The Pentair air and water sensors (same part) are rock solid in terms of longevity - my air sensor sits just below my panel and gets blasted with afternoon sun. It routinely reads +130F during the day. It also reads below freezing in the winters.

One more plus for the replacement flow switch route - when you have an equipment pad layout like mine where it’s highly suggested that you’re a practiced contortionist, cutting and splicing in the new switch is just easier the trying to drill into a pipe while executing the “downward facing dog” pose....

- - - Updated - - -

Quick Update -

Dead thermistor is reading 9400 ohms at room temp (78F)....not as far off as I expected it to be

 

[JamesW]

Dead thermistor is reading 9400 ohms at room temp (78F)....not as far off as I expected it to be

That odd. It seems inconsistent with the test. Maybe the resistance is inconsistent under different conditions?

Maybe under the stress of the water flow, the bend in the stalk is enough to open a crack in the thermistor.

Maybe put the multimeter on the thermistor leads and slightly stress or bend the stalk to see if the resistance changes.

Maybe try warming or cooling the thermistor to see if the resistance changes smoothly or begins to become erratic.

Also, check the multimeter by connecting the two leads of the multimeter to make sure that the reading is 0 ohms.

 

[bdavis466]

The generic version seem to work just as well and are $40-50 less.

This year has been crazy for the IntelliChlors. I bet I've replaced at least 10 flow switches and gotten several calls where switch replacement was my suggestion. Perhaps pentair sent out a signal to make all the switches fail? :batman:

 

[JoyfulNoise]

The generic version seem to work just as well and are $40-50 less.

This year has been crazy for the IntelliChlors. I bet I've replaced at least 10 flow switches and gotten several calls where switch replacement was my suggestion. Perhaps pentair sent out a signal to make all the switches fail? :batman:

Yeah, I saw the generics on Amazon too. Didn’t want to take a chance that they were using the wrong pitch on the plastic threaded nut or the wrong thermistor. $95 plus shipping on Amazon from PST Pools out in your neck of the woods. Got it in 3 days even though I paid for “back of a mule” shipping. I called around locally but either no one had it in stock or they were marking it up. My one favorite shop wanted $230 for the part

If it goes again, I already have the water temp thermistor on hand and the wires are all spliced so I’ll go that route. I’m thinking I’ll use your contractor business ID and just go straight to Harwil Inc and buy a palette of them for $0.50 per piece

 

[bdavis466]

Odd that yours just gave a lower salt reading. The ones that I've seen go bad all say the salt is at 0 PPM.

I really wish Pentair would change the design of the cells

 

[Jimrahbe]

Odd that yours just gave a lower salt reading. The ones that I've seen go bad all say the salt is at 0 PPM.

I really wish Pentair would change the design of the cells

Brian,

I can't see how the flow switch can cause the zero salt problem...

Based upon the failures reported here, I know that replacing the flow switch has "fixed" some, but not all zero salt issues.. Even new cells have not fixed the problem for everyone.

Normally, when the problem is that the EasyTouch reads zero salt, the cell actually knows the salt level and it is just not being reported to the EasyTouch. It appears to me to be a timing or communications issue between the cell and the ET. Also, based upon the reports here, Pentair does not appear to have a clue as to what the actual problem is.

In my case, I have had the problem twice, and just rebooting the system made it come back to life. I suspect my components are just closer to the tolerance needed to make the system work..

Thanks,

Jim R.

 

[jimim]

My cell is an example of this. My unit was reading zero. They sent a replacement flow switch to my builder. Installed. Still zero. Sent a new cell now working.

Its so weird. Very random

 

[JoyfulNoise]

Odd that yours just gave a lower salt reading. The ones that I've seen go bad all say the salt is at 0 PPM.

I really wish Pentair would change the design of the cells

The salinity readout has been wonky all summer. JamesW’s secret diagnostic procedure (yeah Pentair, can’t tell your customers about that ??) helped me to know that the thermistor was going bonkers. And yes, Pentair really needs to up its game on the SWG design and interface. As best as I can figure out, they gear their design methodology to focus on their suppliers and installers rather than the end-user. It’s as if they really don’t want the pool owner to touch the equipment. I think they’re making a big mistake with that “design philosophy” but only time will tell.

 

[JoyfulNoise]

Brian,

I can't see how the flow switch can cause the zero salt problem...

Based upon the failures reported here, I know that replacing the flow switch has "fixed" some, but not all zero salt issues.. Even new cells have not fixed the problem for everyone.

Normally, when the problem is that the EasyTouch reads zero salt, the cell actually knows the salt level and it is just not being reported to the EasyTouch. It appears to me to be a timing or communications issue between the cell and the ET. Also, based upon the reports here, Pentair does not appear to have a clue as to what the actual problem is.

In my case, I have had the problem twice, and just rebooting the system made it come back to life. I suspect my components are just closer to the tolerance needed to make the system work..

Thanks,

Jim R.

My cell is an example of this. My unit was reading zero. They sent a replacement flow switch to my builder. Installed. Still zero. Sent a new cell now working.

Its so weird. Very random

Yep. And all I did was shutdown the system, replaced the flow switch assembly then powered it all up again and I got a zero salinity reading. I disabled, then re-enable the IntelliChlor and then power cycled the filter relay. That finally got it to send a reading to the ET panel. I’ve never put much stock in the ET panel readout because I’ve had a hunch that the 12 hours update interval for the salinity measurement only gets transferred to the ET panel from the SWG’s non-volatile memory IF the panel queries the cell while the output is on. Otherwise the panel fails to get the latest reading and just sits on the last one.

The only way to know for sure is to go and buy an IntelliWand and a laptop running Windows XP with a USB 1.0 port. Then you can actually get some diagnostic info out of the IntelliChlor and see if it matches the ET panel.

Pentair makes some nice equipment but their end-user interface and support is horrible. All of this information should be readily accessible at the panel but it’s not and they hide what information is reported. And I have doubts that their new “IntelliCenter” does any better....