When such a failure occurs, the following 4 parts should be checked:
1) Improper adjustment of hot and cold-water valves. Re-adjust.
2) Check whether the connector end of the heating tube has poor contact or broken line. Remove the bad contact or broken line point.
3) Inspect the heating tube for damage. Replace the heating tube.
4) The thermostat contacts are in poor contact or the thermostat is damaged. Repair or replace the thermostat.
[Tips]
The heating pipe is good or bad judgment: use a multimeter to measure the resistance to infinity (normal tens of euros), indicating that it has been damaged and needs to be replaced.