To answer your question, please refer to my blog on how to change flow sensor:
https://gr8place2go.blogspot.com/2023/04/di...-hot-water.html

Another case on Rubine IA991D DC Pump Instant Water Heater, just take out the flow sensor, clean it and realign it.
https://gr8place2go.blogspot.com/2023/09/di...ine-ia991d.html

My initial suspect is flow sensor (magnet) or Reed Switch spoilt.
Rubine flow sensor (magnet) might be slightly pricey compared to Joven.

Hope this is helpful to you.

This post has been edited by gosleo: Feb 6 2024, 12:33 PM

Alpha EVO-i have ON/OFF Pump Switch and also a separate knob to adjust MIN to MAX.



30: Pump Control Knob (Min to Max)
32: Pump ON/OFF Button