I do understand how the heater is operating and regardless of how warm or hot the room has reached, whilst the heater is plugged in and in use, and on heat setting 2, exactly every 6 minutes, the heater cycles on for a few minutes, then off.
Although, when the heater is turned off and unplugged from the wall outlet, it takes just short of 3 hours, before the warmth of the room drops sufficiently, to feel the need to turn the heater back on.
So, you honestly believe, that even when the heater is on and in front of an open patio door, with a outside winter temperature of 4°C, the heater still cycles on every 6 minutes then off, rather than remaining on throughout the entire duration the patio door is open !
Do your own monitoring with your own electric converter heater before you start stating I don’t understand in such a manner.
And if your electric heater operates differently to that of mine, then provide the make and model, and I’ll make enquiries with the manufacturer, to clarify whether the “Adjustable thermostat control and easy-to-use dial” is just that, rather than what I’m currently encountering.