We just installed our pool in Jan with an Easy Touch system and the instructions recommended placing the water temp sensor on the pipe between the pump and filter. This gives a temp on the water returning from the pool. Look for a small (about1" in size) relatively flat black plastic object heled against the pipe with a hose clamp. There will be small gauge black wire coming from your sensor back to your Easy Touch box. A hole (roughly 1/4") is drilled into your pipe and the sensor is inserted so that it makes contact with the water. If you determine that you need to change the sensor, it is pretty easy to do. The Easy Touch installation manual diagrams it well. If you don't have that manual, you can download the pdf file from the Pentair site. Also, I'd suggest you call Pentair tech support for guidance. During installation of our system, we made multiple calls to Pentair tech support and were pleasantly surprised with the great tech support we received. Hope this helps.