Z-TRM3 floor sensor

So I’ve been running a Z-TRM3 unit with a floor sensor in my concreate bathroom floor for some years, and it has been working stable, but there has always been an issue with the shown temp on the display and the measured temp by a tired party thermometer. When set to 40C on the display the measured temperature is 23C in the room, I’ve sort just lived with it, but I would like to calibrate it. I don’t know if it matters, but the unit is placed in the wall outside of the bathroom, and I have checked that the floor sensor(F) is selected as sensor.

I’ve found the parameter in the app CAF in parameter 11, so normal thinking would be to set a value of -17C to correct the reading, but the instruction’s say when keying in a negative value, use 256 and subtract the value, so that would be 256-17=239. When you you look at the range specified for parameter 11 it reads: -60 - 60 so 239 would be outside of the range.

So my question are, how do you calibrate the floor sensor, oh and I want to ask, what does the hysteresis(DIFF I) control, mine is set to 5?

So is it only me that have to calibrate the floor sensor?


Haven’t needed to calibrate the floor sensor.

Are you sure that you have selected the right type of ntc sensor in the device?

From where you measure the calibration temperature? If you compare the floor temp to room air temp that will be almost always different.

Thank you, yes I have use the standard value for the sensor as described in the manual.
I’ve measured the air temp in the bathroom, and it’s to much off what I see in the Z-TRM3 display. It isn’t really a problem, but just annoy me, that’s why I want to adjust it.


OK. Now I understand the problem.

If the Z-TRM3 is configured to floor sensor mode(F) the measurement in the display might show the floor temperature not the room temperature.

This can be changed in the device. Set the Temperature display setting into “Display measured temperature” and the Displayed temperature setting into “Internal sensor (default)”

Thank you again.
That would be an easy fix, but the unit is placed in the hallway outside of the bathroom, so it would show the temperature in the hallway, not the bathroom, if I understand right?

So I think you are right, it shows the measured temp in the floor, but the wall unit should translate the floor temp to room temp when you calibrate it, I think.


It can’t translate the floor temp to room temp in any case. They are just not the same. The floor gets always hotter when heating and lowers when not heating so the “calibration” between the floor and room temp should change and thats not possible with this device.

Yes I know, but the thing is that this will be a calculated value, so when I set 23C at the display/wall unit it doesn’t read 23C in the floor it have just been calibrated so it thinks it read 23C in the floor. Like in this video: https://www.youtube.com/watch?v=cbvSXWjPrsE&ab_channel=ArcaNovaGruppen . Sorry for the Norwegian langue in the video, but what he is doing is setting the wall unit 1C higher then he have measured in the room with a third party thermometer.
As I have a negative value to enter the user manual state that I will have to type in 256 - the value(17C) and that doesn’t make sense.