I can't see the line. I can tell you an idea. Your current situation is that the switch wire has passed through the insulation switch. It should be that the switch wire is directly connected to the heating pipe, and there is no insulation switch. In general, the heat preservation is not controlled by the switch. That is to say, after the switch is turned off, the power supply can continue to supply power to the heating pipe through the insulation switch, and it will automatically turn off only when it reaches a certain temperature. FYI