I made a set of infrared heater plus Sonoff TH16 with 5m Sonoff AL560 extension cable and Si7021 sensor. Previously I used the same set with the AM2301 sensor. The problem is that the measurement is terribly slow or it doesn't work. The difference between another thermometer and a Sonoff is 1 to 1.5 degrees Celsius. Moisture measurement is either very slow or hanging in one place. Each sensor reacts with a long delay. I don't think it's a continuous measurement. I've come to the conclusion that the sensor is picking up too much temperature from the cold wall and this is interfering with the results. At the moment I put a 5mm cork under the sensor and I am waiting for the results but I am not fully satisfied with it. Where can the cause be? I don't think that every next sensor is damaged. The firmware version is 3.3.0 so is newest.
I must add that the sensor has been placed at a height of 1.5 m from the floor.