Pentair 42001-0053S Electrical Systems Thermistor Replacement Pool and Spa Heater

My original sensor shot craps and after looking at videos, I decided to try this OEM unit as it was much less expensive. So far, so good.

My spa heat wasn't working because it thought it was hotter than it actually was. This fixed that problem and fit perfectly!

Works as expected

Funciona bien

After troubleshooting with the owner's manual, this appeared to be the problem - heater wasn't firing because it thought the pool temperature was already over the set point temperature. Quick delivery, relatively inexpensive, and a perfect fit solved my heater issue.

Worked great. Solved my problem with my pool heater.

Worked as advertised. Heater works as it should.

3-4 yr old Pentair unit. I did a bit of YouTube research to determine the cause of my spa not heating up the pool. In my case, there were no error codes being displayed on the Pentair heater unit but the water temp never went up. After a few guesses, I suspected the thermistor unit. While others on YouTube showed their used thermistor in pretty bad shape, mine looked a bit worn with what looks like calcium deposits.After removing the side panel (with the water inlet/outlet are), noticed the new thermistor was exactly the same size as old one (read about others having diff sizes when replacing). I suggest using a small flathead screwdriver to help wriggle the connectors out from the old unit.Used an adjustable wrench to remove the old unit and replaced it with new one. Tighten it up to the depth of the pre-installed tape on threads. Then reinsert the connectors. Total time: 15 minutes (going slow).Fired up the heater and got a nice hot spa!

it did the job and saved me from having to buy a new heater

Temperature was a reading wrong as in way too high on my Pentair 4000HD. This fixed it by replacing the sensor

ok

excellent delivery and it worked just fine