Phillips screwdriver (Cordless drill is even better).
Crescent Wrench or Channel-locks
1” square piece of sandpaper. (Fine grit is best).
Turn off power at the GFCI.
Remove the access panel.
Your Flow Sensor installation looks like one of these photos.
Before you get started, note that you can see about 2-3 threads. At installation, if it’s screwed all the way down, the sensor will not operate properly.
Also note the correct orientation of the “flapper”. The water flows from left to right, pushing the flapper towards the post. If it’s not lined up as shown, the sensor will not work.
Use the metal plate covering the PC Board to protect the pump below the flow switch. Water will flow as you begin the next step.
Using a Crescent wrench or Channel-lock, unscrew the sensor from its housing.
Remove it from the sensor housing. Quickly install the new sensor. (You’ll lose a little water, but the plate will protect the pump below.) Turn the sensor until there are 2-3 threads showing, and then adjust it to the correct orientation. (See steps 4 & 5).
Look on the wiring diagram to locate the flow sensor connector. The location varies from model to model. The connector only fits 1-way, so take note of its wire orientation before unplugging. Remove the flow sensor connector from the circuit board.
Using a small strip of your sandpaper, sand the 2 pins on the circuit board. Nothing fancy, just a few swipes on each side of each pin to improve the connection. Plug the new connector back onto the circuit board.
Turn power to the spa on at the GFCI. Within 1 minute, the “Flo” message should be gone and the spa should start heating.
If the “Flow” message is still showing, turn the power off again at the GFCI. Confirm the flapper orientation is correct, and the connector is properly mounted onto the circuit board. Turn power on again at the GFCI.
If the “Flow” message is still showing, call us for help.