Showing wrong temps

I have two new sensors, one in freezer one in fridge. The new fridge is working great… but at coldest setting the freezer is reading 19deg F and fridge is 46 deg F, an IR temp gun shows freezer at 0F and fridge at 34F which seems more acceptable. How can I fix this?

Usually when people suspect that RuuviTags in fridges show wrong temperatures, it turns out that RuuviTag was right and showed a problem in the fridge.

First thing to note is that the IR gun will measure the surface of the fridge while RuuviTag measures the air. Fridges can have very different temperatures depending on if the Tag is in the back or front of the fridge, same for up or down.

You can try to put RuuviTag as close to the IR measurement point as possible, i.e. touching the back wall. However, measurement taken in the middle of the fridge might be more meaningful for monitoring the conditions food is at.

You could also try measure e.g. milk inside a carton next to RuuviTag to see at which temperature the milk has settled in.

Another thing to keep in mind with IR thermometers is that anything that “reflects” IR will show a temperature reading that’s a mixture of the surface and whatever reflected, so very shiny surfaces (for IR, not necessarily visible light) will be noticeably affected by the “reflected” temperature.

To get an “accurate” reading with an IR thermometer, I would suggest placing a piece of non-glossy or matte paper (ie. regular printer paper or similar) in the middle of the freezer and let the temperature equalize before measuring that. To accurately compare to the tag, I would suggest placing the tag in the “center” of the freezer, equally far from all walls and place a piece of paper on top of the tag, let the temperature equalize (maybe an hour or so to be sure), and then measure the paper with the IR thermometer and compare that to the tag.

And another thing regarding measuring freezers (and fridges to a lesser extent) is that the tag, especially if kept in the enclosure, will “lag behind” a little bit as the cooling cycles go, since it takes a little bit of time for the temperature changes to conduct through the enclosure and change the temperature of the tag itself, since the tag technically measures its own temperature, which is mostly affected by the temperature of the surrounding air.

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So far three independent tools have measured 10 Degrees cooler than the Ruuvi. I’m using the ir thermometer on items in and near the sensor all reading much cooler. There is ice on back wall of refrigerator. I’ve swapped tge sensors. The fridge has extensive air flue around it.

Do they show also wrong temperature in room temperature?

Yes, they read about 6 to 7 warmer

Could you check from the sensor settings that there are not set any offset calibration? (right top corner)