Hi, ı have 2 Sonoff Zigbee Thermostatic Radiator Valve and Sonoff SNZB-02D Zigbee LCD Smart Temperature Humidity Sensor in same room. Temperature measurements are different in these 3 devices. Is this normal? Where is the problem?
From my point of view it’s kind of normal an has some logic.
First of all you don’t measure the temperature in the same spot. What I mean to say is that the TRV is on the radiator and the temperature sensor is in a different spot in the same room.
Especially, when the radiator stats heating you get a higher reason on it than on the temperature sensor.
This is why, on the TRV you have the option to “calibrate” the temperature, meaning you can a adjust the temperature so you can get closer to the temperature sensor, but it will never be the same.
A nice feature on the TRV would be to replace the internal temperature reading with an external one, like this you can get a more precise heating of the room.
My experience with smart TRV (not Sonoff as I bought them before they had any) is that the temperature accuracy is much better if the valve head goes sideways rather than vertical. Not all valves can be turned though because of the extra space needed. I still have a few vertical ones. The ones I have also have a temperature calibration option, although it tends to be different if the radiator is on or off so a curve would be better than a fixed value. Mine default from the factory to -2°C, which I think assumes you’ve not turned the valve and the radiator is on.
I couldn’t find this feature. Where is it?