Question: I need to replace the external sensor on a Magna, can I repair it and how do I replace it?

Answer: If the sensor (P/N 97471249) is malfunctioning, it is most likely due to being contaminated and not defective. If it was defective, it would not work as soon as the pump was installed. The good news is that cleaning them is not that difficult.

After the pump has been isolated, remove the stainless steel ground screw and slide back the support clamp that is fitted in the grooved rails.

Sensor Dirty

Next gently pull out the sensor and be sure to remove the rubber boot that covers the sensor that often stays stuck in the hole. Next open up the supply valve and blast fresh water through to clear out any last debris. Clean both the sensor and rubber boot and verify that there are no dirt particles or magnetite in the two sensor eyes or built up inside the boot.

Do not under any circumstances use any metal cleaning tools because it will damage the glass inside and damage the sensor eye. Once completed, reinstall with the “bump” side on the sensor boot facing away from the volute. You will know if you installed it backwards because the pump head screen will not light up.

After the ground screw and clamp is securely fastened, slowly open up the supply to check for leaks. Now you are done.

If the problem re-appears, then it is a usually a system water quality issue. A Spirotherm VDT air/dirt eliminator unit will clean up the system. Once it is in place, run the pump at maximum setting periodically to allow the debris to come out of suspension and use the purge valve to keep blowing it down in a clean white bucket until the water looks clear.

The replacement sensor kit that includes the sensor wire cable, mounting bracket and screw as P/N 98471249.  

Good luck!