Heater Won't Fire

[ajw22]

One final question (at least for now): If the resistor test indicates that the new Pentair thermistor is not defective, is there anything else that might trigger the "E01" error code (& prevent the heater from firing) before I replace the circuit board?

E01 code is an open water temperature sensor. The wiring between the thermistor and the board could be at fault.

Carefully check the spade connectors that slide onto the thermistor.

 

[Kit]

Just to be safe, I replaced the spade connectors. Unfortunately the E01 code persists.

 

[ajw22]

Did you measure the resistance of the thermistor?

Since the E01 is an open sensor it says there is no continuity at the thermistor or one of the wires to it.

I would use the multimeter and check the resistance and continuity of the thermistor and the wires leading to it. Test from the connector at the board to the spade lugs and see if both wires have continuity.

 

[generessler]

E01 means the sensor is open. That can be checked easily with a meter that measures ohms. I happen to have a new extra. It's about 68F here, and it's measuring 9,200 ohms (9.2k).

The reason i have the extra is that I also got the E01 code, and it turned out to be a bit of corrosion in the connector where the thermistor wiring meets the board. Spritz a bit of CRC Contact Cleaner, disconnect and connect a few times, and it's been fine ever since (at this point a couple of heating seasons).

Not saying that your problem isn't more severe (like a bad board). But it pays to rule out the cheap stuff first.

One more thing: The troubleshooting section of the manual is actually pretty good. Worth a study...

Good luck with it. My heater is easily the crankiest bit of hardware on the equipment pad. Happy tinkering.

 

[Kit]

ajw22 & generessler: Thank you so much. Although I did replace the spade connectors at the thermistor & visually inspected the wires, your suggestion regarding checking the resistance & continuity is something that I failed to do.

I must admit that diagnosing electrical issues is my "Achilles Heel". Although I have used a multimeter on various occasions, my cursory understanding of the principles of electricity has restricted my confidence when using it.

Therefore, just to verify your suggestions......are you suggesting that I disconnect the wires at the thermistor & at the board & check their continuity? I assume there should be virtually no resistance. Then do the same across the terminals on the thermistor? Ideally, what should the resistance be across the connectors of the thermistor if the thermistor is not defective?

Thank you for walking me through this.

 

[ajw22]

Therefore, just to verify your suggestions......are you suggesting that I disconnect the wires at the thermistor & at the board & check their continuity?

Correct.

I assume there should be virtually no resistance.

You should see the difference on your multimeter display between an open circuit and 0 resistance.

Take the probes and touch them together and see what it displays with continuity.

Then look at what it displays when the probes are not touching.

Then do the same across the terminals on the thermistor?

Correct.

Ideally, what should the resistance be across the connectors of the thermistor if the thermistor is not defective?

​

Temperature Sensors - Further Reading

www.troublefreepool.com

 

[Kit]

Here are my test results: The resistance across the thermistor terminals (with air temperature at 53F) is 14.22K ohms. According to the resistance chart, the resistance is 18.4K ohms.

The continuity of the 2 wires (tested from the spade connectors to their respective connectors on the board are as follows: 97 ohms & 41 ohms. On each of the wires, the audible continuity signal on the multimeter was steady. As per your suggestion, I sprayed the connectors of the wires with contact cleaner.

Finally, I measured the resistance between spade connectors of the 2 wires when the other ends of the wires were connected to the board. The resistance was 21K ohms. I don't know if this measurement has any relevance.

Do any of these readings offer any insight as to whether the thermistor or the wiring might be the issue? As usual, thank you!!

 

[ajw22]

Nothing obvious.

Did you test the thermistor while it was screwed into the heater?

Is the heater sitting in the sun?

14.22K corresponds to an temperature of about 63F. While the air temp was 53F if the thermistor was screwed into the heater you were measuring the temp of the heater chassis which could be a big heat sink.

The thermistor is not open but it should not be off by 10 degrees.

An accurate way to test the thermistor is to remove it from the heater and submerge it in some water over the range. Put a candy thermometer in the water and connect your multimeter to it. Then see what the multimeter reads versus the thermometer as you heat the water up to 100F.

Or you can use cold water and hot water from your faucet and compare temperature readings.

 

[Kit]

Oops. I did test the thermistor wile it was installed in the heater. I will retest it using your suggestions.

No. The heater is not in the sun. 'Tis an overcast day.

Well, I'm going back out to the heater.

 

[Kit]

I removed the thermistor & checked the ohm readings at different temperatures. I must admit that the readings tended to jump around. Maybe the thermistor needed time to adjust to a change in temperature. In any event, here are the readings I got: 52F (13.28K); 71F (11.1K); 85F (8.83K); 92F (5.9K); 99F (5.16K). Although some of the readings varied from the spec chart, the ohms tended to decrease with temperature. Your thoughts?

 

[ajw22]

Is that a Pentair original themistor or a 3rd party replacement?

The thermistor sounds good but not very accurate.

 

[Kit]

It is a Pentair thermistor from Amazon. FWIW, I just reinstalled the thermistor after running the resistance tests. For some unexplainable reason, the heater actually fired & ran for about 2 minutes. It then shut down & flashed the same "E01" error code.

I mentioned earlier in my post that I had removed the thermal regulator & tested it under hot water. I did not open. Thus, I ordered a new one which should arrive early next week. Maybe reason why the heater briefly fired this time & then shut off was due to the faulty thermal regulator. I guess that I will know after I install the new one. But that still does not explain the "E01" error code. Is it cocktail hour yet?

 

[Kit]

For a test replace the thermistor with a 10K resistor.

If the heater starts and reads 76F then you have a problem with the new thermistor.

If you still get the E01 then you have a problem with the wiring to the thermistor or the board.

Are there any signs that rodents have been in the heater?

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

Temperature Sensors - Further Reading

www.troublefreepool.com

I finally got the 10K resistor (1/4W) & connected it between the 2 thermistor wires. The heater fired & ran until a water temperature of 70F was reached. At which point I turned the heater off. No more "E01" error code. Thus, I assumed that the new themistor was bad.

However, out of curiosity I disconnected the resistor & reconnected the thermistor. Surprisingly, the heater fired up immediately & ran until the pool circuit set temperature of 80F was reached. I'm puzzled!

Finally, I turned on the spa circuit which has a set temperature of 100F. Again, the heater fired immediately. The heater shut off at 98F and cycled off & on. However, I think this might be due to a faulty thermal regulator that I mentioned earlier.

So, I am not sure where the glitch is. I would like to believe that the system somehow reset itself. But I guess all I can do is see whether the problem resurfaces again.

If anyone has any logical explanation, please let me know. Thank you so much!!

 

[ajw22]

However, the display on the heater reads 45F (& not 76F as you indicated). Is this significant? Thank you.

45F indicates a resistance of around 22K.

Disconnect the connector for the thermistor wires at the board and use your multimeter and test the resistance of the two wires. Is it 22K or 10K?

Did you test the resistance of that resistor with your multimeter?

How did you connect the resistor to the wires?

 

[Kit]

ajw22: Sorry that I didn't see your response prior to my last post.

I connected the resistor to the thermistor wires as in the photo you provided. Prior to attaching the resistor to the thermistor wires, I checked the resistance of the resistor with my multimeter (9.94K ohms).

Just a thought....all of my system equipment is run through an EasyTouch control panel. As such, would the temperature reading on the heater display be reliable? I might be showing my ignorance here.

 

[ajw22]

I see you edited the post after I saw it.

Looks like it was some type of wiring problem that your various tests got fixed.

The heater display is independent of your EasyTouch system and displays what the heater thermistor measures..

 

[Kit]

I see you edited the post after I saw it.

Looks like it was some type of wiring problem that your various tests got fixed.

The heater display is independent of your EasyTouch system and displays what the heater thermistor measures..

Thanks, Allen, for you help. For now I will keep my eye on how the heater functions.

As a side note, I looked at the order I had placed with Amazon for the new thermistor. It was listed as "a Pentair Thermistor part #42001-0053S replacement". I assumed it was a Pentair product. However, I can see how the wording could suggest that it was actually an aftermarket replacement. I paid about $20 for the part. Subsequently, I came across (what I had assumed to be) a Sta-Rite Pentair thermistor for $95. If indeed I ended up with an aftermarket part, maybe it was a poor substitute for the genuine Pentair part. I don't know.

 

[ajw22]

Yup, I thought all along you did not have a genuine Pentair thermistor. The ones not from Pentair are variable quality.

 

[Kit]

Just an update.....for whatever reason, the heater has been working fine. The new thermistor (possibly an aftermarket part) has decided to work. No error code anymore. I wish that I could tell you what I did to resolve the problem. If the problem resurfaces, I will be sure to get a genuine Pentair part.

Also, the new thermal regulator solved the on/off cycling issue that occurred when the temperature approached the set limit.

So, at least for now, all is right with the world. Thank you for your assistance. Very much appreciated!