When the PID probe fails, there is no heat at all or there is an error on the LCC (hidden PID parameters were changed). If there is an overheat situation, the LCC will show the correct temp, but the PID sensor (usually in the steam boiler) developed oxidation, limescale, or a film on the sensor. In other words, the sensor may be reading of 125 d C, but the actual temperature is much higher where the gauge is reading over 3 bar and steam is spewing from the internal safety valve into the small spout on the lower front wall above the drip tray.
Remove the water softener from the reservoir or disconnect from the water line, and reconnect the water reservoir without a water softener. Place descaling solution or white vinegar into the reservoir and run about 20 ounces through the grouphead. Let it sit for 2 or more hours depending upon solution. Rinse reservoir and fill with cold water. Run about 40 ounces of water through the grouphead and test. If the overheat problem continues, repeat descaling and rinse.
Even a the slightest film build up can cause an overheat. A buildup caused by limescale (magnesium and calcium which results from hard water) or oxidation (caused by distilled, purified, or reverse osmosis water considered as acidic) can cause havoc on the PID sensors. It happens more on the steam boiler than the coffee boiler because the steam boiler runs at higher temperatures than the coffee boiler – so build up is faster. How does this water reach up to these sensors when the level is lower? Very easy! The water boils creating bubbling and steam vapor up the side walls to the top.
Descaling the PID sensor can NOT be accomplished with a descaling of the steam boiler as the descaling solution will never reach the top of the boiler where the PID sensor is housed. After the Bianca has been unplugged from the electrical outlet and the unit is completely cold, the water reservoir will need to be removed from the body, the top cover will need to be removed, and the wraparound body will need to be removed (remove rear feet first to avoid scratching of feet).
The customer will need to remove the PID sensor without bending, nor twisting the red dual thin wires as bending or twisting these wires will get damaged. If either or both dual red wires get twisted or bent, the steam boiler will NOT heat. In most cases, the probe wires need to be disconnected from the brain – make note of the position and take pictures. Please note that there can be another/second PID sensor probe with 2 red wires that are NOT connected to the brain. This was done on purpose, and newer units will not have this extra probe along the right wall of the steam boiler.
Once removed, the internal portion of the PID sensor will need to be wire brushed and/or descaled (metal portion inside boiler only). Reassemble with a little plumbers tape on the threads. Hand tighten and then 1/4 turn with wrench for final seal.
Water Level Probe
The water level probe (similar one) may need to be cleaned as well. The probe (metal rod) should never be lifted up from within the 2 nuts. The wire should be removed from the metal rod probe. The assembly should be removed from the steam boiler by turning the lower larger nut in a counterclockwise motion. Wire brush the metal portion of the probe. Use plumber’s tape on threads to seal.
Many times when either of the above two parts are corroded, the vacuum breaker/bleeder valve will also get build up and cause a slight leak through the spout on the front wall of the Bianca. This part should be removed from the bottom but, then once off the machine, it should be disassembled and descaled as three separate parts. If it still leaks after testing, it will need to be replaced.
In very bad cases, the safety valve can be corroded with limescale or oxidation. In this case, it should be replaced as descaling can impact the effectiveness of this part.
The water being used in the Bianca will need to be reviewed with the customer to prevent limescale, oxidation or a biofilm. The water softener needs replacement every 6 months. The water softener, if less than 6 months old, should be recharged minimum once every 2 weeks with a cold salt water bath for 20 minutes and rinsed for 5 minutes.