Chiller Flow Sensor Replacement

Applies to: MIRA and NOVA machines with an internal chiller

This guide shows how to replace the chiller flow sensor. Replace it if the sensor fails.

What you need

• Phillips head screwdriver
• Wire strippers
• Wire cutters, or an equivalent cutting tool
• Heat gun
• Replacement flow sensor
• Solder seals
• Zip ties
• Paper towels
• Water container

Remove the old sensor

1. Make sure the machine is off and unplugged.

2. Drain and remove the chiller. Follow the chiller removal guide for your machine in the maintenance guides.

   

3. Use a Phillips head screwdriver to remove the mounting bolts of the rear cover plate, on the top and around the rear of the chiller. Do not touch any screws on the face of the chiller.

   

   

4. Take off the cover plate and set it aside.

   

5. Find the flow sensor and note the direction of its arrow. Take a photo for reference. The replacement sensor must be installed facing the same direction.

   

6. Cut the zip ties that bind the flow sensor wires, taking care not to damage any wiring.

   

7. Slide the foam cover back and cut the ties that hold the silicone tubing to the flow sensor. Take care not to damage the tubing. If you do damage it, contact support.

   

8. Cut the two red wires from the old sensor, leaving enough slack for soldering. Cut close to the old sensor.

   

9. Pull the tubes off the old sensor and set the sensor aside. Some water is likely still in the sensor and tubing, so have paper towels ready.

Fit the new sensor

1. Fit the silicone tubes to the new sensor, with the arrow facing the same direction as before. Secure the tubes to the sensor with zip ties.

2. Strip about 1/2” of sheathing from the wire ends on the new sensor, and from the wire ends left in the chiller where the old sensor was attached.

   

3. Twist the end of each stripped wire into a tight coil.

   

4. Slip a solder seal onto each wire from the new sensor (2 seals in total).

   

5. Bend the end of each twisted wire into a small hook.

   

6. Hook one wire from the new sensor, which carries a solder seal, to one of the wires left in the chiller. Pinch the hooks together to secure the connection.

   

7. Slide the solder seal over the connection. The gray or silver bead in the center of the seal must sit directly over the wire connection, with the red spots at each end over the sheathing on each side.

   

8. Connect the remaining two wires the same way.

9. Activate both solder seals with a heat gun, one at a time. Apply the heat in a steady, broad sweep from end to end of the seal, rotating gently so all sides are heated. The seal is activated when the gray center bead melts to a metallic silver, the plastic shrinks to fit the wire, and the red spots at each end melt and release. The red spots are the glue that secures the seal.

   

10. Let both solder seals cool fully. They turn a smoky white when cool. Do not pull on the wires while the solder is hot, or the connection can come undone and will need to be stripped and soldered again.

    

11. Once the seals are fully cool, give each connection a light tug to check that it is secure.