Thermistor reading
- Thread starter aaron_w_o
- Start date
here's a longer and more elaborate video of the plumbing setup that was requested.
please let me know if this is more clear and easier to follow. I am not an expert but I am not crazy about the 1.5" line mixed with 2" line and the number of elbows and reducers. My plan is to change the aboveground plumbing to be almost all 2" and using sweep elbows, but that's for another day. right now I am trying to just understand the short cycling heater and the new issue with the flow light on the SWG. After pulling the castle off the thermal regualtor, it was quite obvious that part is stuck closed and not operating. hot tap water did not open it. It is corroded and stuck shut... possible culprit for sure as far as the short cycling goes. I have a part arriving thursday this week to see if that fixes the issue. I have not yet tried the test where the thermal regulator is totally removed from the unit... I also ordered the other valve/flap that is on a spring which goes inside the manifold. I hope I dont have to replace that, not keen on pulling the manifold off. at least changing the thermistor wasnt a challenge. I believe someone also asked for a photo of the inside of the thermal regualtor chamber... I will try to take that photo later today and post here. please give some feedback on the video link I posted above in this post.
please let me know if this is more clear and easier to follow. I am not an expert but I am not crazy about the 1.5" line mixed with 2" line and the number of elbows and reducers. My plan is to change the aboveground plumbing to be almost all 2" and using sweep elbows, but that's for another day. right now I am trying to just understand the short cycling heater and the new issue with the flow light on the SWG. After pulling the castle off the thermal regualtor, it was quite obvious that part is stuck closed and not operating. hot tap water did not open it. It is corroded and stuck shut... possible culprit for sure as far as the short cycling goes. I have a part arriving thursday this week to see if that fixes the issue. I have not yet tried the test where the thermal regulator is totally removed from the unit... I also ordered the other valve/flap that is on a spring which goes inside the manifold. I hope I dont have to replace that, not keen on pulling the manifold off. at least changing the thermistor wasnt a challenge. I believe someone also asked for a photo of the inside of the thermal regualtor chamber... I will try to take that photo later today and post here. please give some feedback on the video link I posted above in this post.
Have you checked the error lights on the back of the board when the heater shuts down? You'll have to remove the board and watch from the back to see what happens as the heater starts its ignition/heating cycle.
Not sure if it is the video itself, but the blower does not sound good.
Normal startup display on the heater is:
Display on and 888
Service Heater lights and goes off
Service System lights and goes off
128 r14 displays (128 is NOT the temperature but the software and revision of the board)
Normal startup of heater begins (blower, etc.)
Hopefully you're not basing your troubleshooting on that number. The LEDs on the back of the board will direct you to the best place to start. Did you try running the heater with the thermal regulator out? Did you look into the manifold and see if the internal bypass is broken?
Short cycling is almost always the result of, first poor water flow through the filter system, just enough to close the pressure switch but too little getting too hot tripping the high-limit or ags switch. Or, second poor water flow through the internal passages of the heater, most notably the internal bypass. Too much water bypasses the heat exchanger, the rest gets too hot and trips the High-Limit or Automatic Gas Shut-off switch (not sensors).
Hi, have not checked lights in back of board yet, nor running with regulator out. I plan to do that today and tomorrow. Got a lot of stuff on the go. And no I did not base my troubleshooting of the thermistor on the startup numbers, it was based on the temp showing 126 (not 128) and not coming on at all. New thermistor allows it to come on but short cycle like last year. When I pull the regulator i will take a photo of the internal
Bypass if that can be seen via the chamber. Agree blower sounds a little rickety. Can’t recall if it always sounded like that or if that’s “new”. Believe it always had that sound. More work to do here!!
so guess what... can't get it to short cycle today. no idea why. other than it knows I am trying to record it?! nothing changed other than I pulled the termal regulator and then of course re-seated it yesterday. The heater has been running steady for 10 mins now, it used to only ever stay on for about 2 when short cycling. I am going to see if I can reproduce over the next couple days, and make a video when it happens. will post here. I am still quite certain the regulator is broken, as the tap water did not open it at 125F. And now of course the flow light on the SWG is on... that hasnt gone off today. both issues are intermittent: the short cycling and the SWG flow light. I dont think they are mutually exclusive. I will leave the heater running for an hour and see if anything changes. After that, I will pull the regualtor to take a photo inside the chamber. I will also be swapping out the 90 elbows for sweep elbows and upgrading several pipes to 2"... something have been meaning to do for ages. I promise I will get video of the short cycling on the MT control panel and also the control board LED lights (backside). I also promise to get a photo of the inside of the regulator chamber. MURPHY!
Perhaps I misunderstood, but this is from your earlier post: "here's heater startup video... kinda tough to shoot alone but if you missed it, the heater comes on, the red lights both flash, it displays 128 as a temp, then R14, then the water temp... and the heater light beging to flash amber indicating the demand for heat is there."
It is possible that there were/are two issues with the heater, a bad the thermistor that can test good out of the heater (replaced?) and a bad internal bypass, which can cause short cycling.
yes you are right, that is what I wrote, but I was the one mistaken... I should have just said it says 128 , then r14... I was thinking it showed 128 where the temp is normally shown... but it came out wrong. apologies. I can swear on my pinky that when it wasnt lighting at all, the water temp (not the startup code) was reading 126... as written the new thermistor fixed that. still baffled about the old thermistor. it looks very good and gives correct readings on my meter. I also dunked it and it was still ok underwater and giving me the correct resistance to the water. my best guess is that the leads on it were brutally corroded. so I will hold onto it with my basket of pool parts and maybe use it someday if the aftermarket one fails. give it one last chance to prove itself.
I agree with you there are 2 issues with the heater. the thermistor definitely was sending a bad temp code... how and why is a mystery but the new thermistor is not doing that. The other issue remains unsolved... and so far today non-reproducible. that is the short cycling. as I said leaving it on for a solid hour to see if anything happens. is it safe to say if my regulator wouldnt open under tap water, that I may was well swap it when the new one arrives this week?
Only reason is the other old one is now working somehow? No short cycle heater been on for over an hour and pool temp up 3 degrees already. Could save the new part for when there is failure?
Other part of me says these sensors are all preventative maintenance items that should be changed over every 2-3 seasons. I still need to get photos inside the regulator chamber and video of the short cycling when it happens again.
Todays progress: got a new flow sensor in my cell and got 2” lines from heater to returns. Still waiting for thermal regulator from Amazon. What would cause a flow switch to crack like this? See the split right up the back shaft.
I also acid washed the cell. !! Quite a bit of maintenance on this gear this season!
Hello, again. my goals for this weekend are to take a photo of the thermal regulator housing inside, as requested. I will also be replacing the thermal regulator part as the new one arrived from amazon today. The cell is no longer showing no flow after the flow sensor replacement was made the other day. Curious about opinions on the crack in that cell flow sensor seen in the photo a few posts back. WIth the thermal regulator, I also ordered the bypass valve. is there anything I should know before taking the darn manifold off the heater to swap it? wish me luck
finally got a video of it short cycling. I have not changed out any parts yet. I have a thermal regulator and a flow regulator valve ready to go here.
It will repeat this loop about every 3 mins... 2.5 mins of heat(solid orange light), 30s of service heater light(solid red light), then 5s of demand(orange heating light flashing), and then 2.5 mins of heat again(heater light solid orange) ... over and over.
It will repeat this loop about every 3 mins... 2.5 mins of heat(solid orange light), 30s of service heater light(solid red light), then 5s of demand(orange heating light flashing), and then 2.5 mins of heat again(heater light solid orange) ... over and over.
The input temperature is not changing at all, so that points to a different error.
Check the stack flue temperature by pressing and holding the "Pool On" button until the SFS temp is displayed.
Check the stack flue temperature by pressing and holding the "Pool On" button until the SFS temp is displayed.
1.....PS (Pressure Switch)
2.....HLS (High Limit Switch)
3.....SFS (Stack Flue Sensor)
4.....AFS (Air Flow Switch)
5.....AGS (Automatic Gas Shutoff).
6.....Service System
7.....Thermistor
8.....Heating
9.....Pool On
10...Spa On
11...Service Heater.
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2.....HLS (High Limit Switch)
3.....SFS (Stack Flue Sensor)
4.....AFS (Air Flow Switch)
5.....AGS (Automatic Gas Shutoff).
6.....Service System
7.....Thermistor
8.....Heating
9.....Pool On
10...Spa On
11...Service Heater.
Pentair MasterTemp Heaters - Further Reading
www.troublefreepool.com
Exhaust Gas Temperature.
While running, press and hold the On button to display the exhaust temperature (Older Models).The new models use the Menu to get the SFS.
Here is what the normal exhaust temperature should be:
- Below 250 degrees...very low
- 250 to 290 ..................low
- 290 to 350.................acceptable
- 350 to 480 ..................high
- Above 480...................error/shutdown.
If the exhaust gas temperature is higher then normal then water may be bypassing the heat exchanger through a broken bypass valve.
If you hold down the "pool on" button, it stays on 80, then flashes to 40, then back to 80, then the 80/40 reading and E05 indicate that the board is not getting a reading from the sensor. It's usually a bad sensor or damaged wires.
Next step is to run it with lid upside down and observe the board LEDs when combustion stops temporarily?
To be clear: my expectation is that the heater will stay on until the set temp is reached, even if it takes hours and it will not cut in and out if all the sensors and valves are working properly. Is this correct, or would it be normal duty cycle for it to periodically cool off by stopping combustion?