Fridge thermometer - possible to calibrate?

[J@son]

I've got a fridge thermometer.... And I am pretty sure it's telling me lies.

When I put it in my modern fridge (which is set to 2 degrees C) it is indicating a temperature below zero.

(I know it looks as though it is showing 2 degrees in.this photo.... But this was taken after I had removed the thermometer for a few minutes to examine it before putting it back to take the photo)

Anyone know whether this type of thermometer be calibrated / adjusted?

If not, can anyone recommend a more accurate alternative?

Pic attached

 

[Dunwaters]

I wouldn’t trust that yoke to measure anything accurately.
Best it’ll do is give an indication of whether or not the fridge is working.
Also, fridges can have hot or cold zones, move the thermometer about a bit.

 

[nun_hunter]

When my dad was having issues (or perceived issues) with a new fridge the engineer put the thermometer inside a glass of water in the fridge. The engineer said that the air temperature inside the fridge wasn't an accurate way to test the actual temperature of food etc.

 

[Pete1774]

I think the "Made in China" text on the dial says it all.

 

[Sampo]

There are digital fridge thermometers available on Amazon under £10 which might be better. You might even find ones with bluetooth and app functionality if you want to keep track of it over the time. It all depends on how accurate you want the temperature to be measured.

Digital Fridge Thermometer - £6.59

Wireless Digital Thermometer - £26.49

 

[chriswjx]

I've got a fridge thermometer.... And I am pretty sure it's telling me lies.

When I put it in my modern fridge (which is set to 2 degrees C) it is indicating a temperature below zero.

(I know it looks as though it is showing 2 degrees in.this photo.... But this was taken after I had removed the thermometer for a few minutes to examine it before putting it back to take the photo)

Anyone know whether this type of thermometer be calibrated / adjusted?

If not, can anyone recommend a more accurate alternative?

Pic attached View attachment 314358

I would advise, just because your fridge is set to a temperature, it doesn't nescessarily mean it is at that temperature either for a variety of reasons. Firstly, as Dunwater pointed out, fridges and freezers tend to have distinct hot and cold spots, and you are "trusting" that the temperature at any given point in that fridge is reading the same as the inbuilt thermometer of the fridge (wherever it's located).

Secondly, there is little reason to trust the fridge's own thermostat as well. They will have a vague calibration, can't imagine it is anything accurate. I work in a regulated chemical lab, where we have to qualify all our storage systems. We use fan assisted refrigerators specifically made for chemical storage, and even when monitoring temps (usually anywhere from 2 hours up to overnight/weekend in each spot) across the whole fridge they can read significantly higher than what the inbuilt is reading. Right now for instance, it's reading at 6.3°C compared to the set point of 4.5°C.

Granted, it will still be above freezing but the point I'm trying to say, is that I wouldn't try to calibrate anything against whatever you're fridge "says" it's set at for the reasons above.

I would suggest that if you get a digital one, stick the probe end in a wee vial of sand and blue tac the top (maybe an empty nailpolish bottle or the like). Same concept as using water, but less prone to freezing (especially if your fridge is set at 2°C, I would be surprised if there are not frost zones!) and you don't have to worry quite as much of knocking it over and causing a massive mess.

 

[75]

Where it was made will have no bearing on it's accuracy but I'm glad to see casual racial stereotyping is alive and well on SD

Best you could do from a calibration perspective is put it side by side with a digital one and then you'll know how far out it is (e.g. it reads 3 degrees low / high) then you'll just have to mentally subtract / add that amount from what it's showing on the dial.

But best option all round is just buy a cheap digital one off Amazon / ebay - will be accurate enough and if you get a bluetooth version you can download the historical data to your phone and see average / trends so gets away from the peaks and troughs you'll see during cooling cycles in the fridge.

 

[Len the dog]

Where it was made will have no bearing on it's accuracy but I'm glad to see casual racial stereotyping is alive and well on SD

Best you could do from a calibration perspective is put it side by side with a digital one and then you'll know how far out it is (e.g. it reads 3 degrees low / high) then you'll just have to mentally subtract / add that amount from what it's showing on the dial.

But best option all round is just buy a cheap digital one off Amazon / ebay - will be accurate enough and if you get a bluetooth version you can download the historical data to your phone and see average / trends so gets away from the peaks and troughs you'll see during cooling cycles in the fridge.

But what do you calibrate the digital one against?

 

[75]

But what do you calibrate the digital one against?

Clearly there is an issue with the OPs dial thermometer which would appear to be a good few degrees out but how accurate do you really need for domestic fridge / chiller etc? I've had a few digital ones and they are always within a degree of each other.

 

[chriswjx]

But what do you calibrate the digital one against?

Good old mercury

Or get something like we use - ETI | High Accuracy PT100 Reference/ Calibration Thermometer

On a slightly more serious note, as 75 found, we have some dozen or so digital thermometers that we qualify against a certified reference thermometer (as in the link). Our acceptance is that they must be within +/- 1°C of the reference probe otherwise they get chucked. Honestly though, the furthest "out" I've seen on one of them was about 0.6°C.

 

[wytonpjs]

Interesting topic this When I first set up my old Pepsi Fridge as a chiller I decided that I needed a more accurate means of temp measurement than a crude LCD panel or dial-type thermometer so I invested in a number of these:

https://www.nisbets.co.uk/hygiplas-digital-fridge-and-freezer-thermometer/f343?vatToggle=incvat&plaid=1&cm_mmc=PLA-_-19658930599-_-148684579569-_-F343&cm_mmca1=go_19658930599_148684579569_647487809739_aud-2064258897315%3Apla-2012539335581_c_&kpid=go_cmp-19658930599_adg-148684579569_ad-647487809739_aud-2064258897315%3Apla-2012539335581_dev-c_ext-_prd-F343_sig-CjwKCAjw-b-kBhB-EiwA4fvKrB-ZrtBqFwAuRY8bVOwatMBBBFA55o5GQ64qLC6SKqF-VslrVMRiuxoCcXUQAvD_BwE&gclid=CjwKCAjw-b-kBhB-EiwA4fvKrB-ZrtBqFwAuRY8bVOwatMBBBFA55o5GQ64qLC6SKqF-VslrVMRiuxoCcXUQAvD_BwE

Having installed these, I then discovered (like others) that whilst you may set a fridge to say 4 degrees (and some even have a gucci LCD display that supposed shows the temperature), the reality is all over the place tempwise due to hot spots, cold spots and how the electronics actually control the compressor. I then migrated to remotely monitored wi-fi based wBox temp sensors in my chiller and game freezer and they give a more accurate reading of actual temperature; the chiller temp sensor is mounted in an old IMR 1lb powder pot filled with water located in the highest (warmest) part of the chiller. The resultant temperature readings are smoothed compared to the saw-tooth instantaneous temp shown on the chiller's digital STC-1000 controller.

 

[Koenig]

As stated the little LCD thermometers are (in my experience anyway) pretty accurate. Mine gives me the relative humidity as well. I’ve found the bottom of the fridge to be cooler than the top - something to bear in mind when positioning. For the £10 mine cost you could of course invest in two in order to give you a fuller picture of what your particular unit is doing.

 

[J@son]

Thanks for the feedback everyone. I'm grateful to everyone who took the trouble to post. Just wanted to make sure I wasn't missing anything obvious!

 

[Peter Eaton]

Ink bird do a heating and cooling plug in device on eBay , likely in the home brew dept . Very cheap with interchangeable probes .

Plug it in , set the parameters , pump on pump times , pump delay times , alarm high and low with the degree of error you accept is ok and set it . It will happily mon things and can be used for loads of other devices within its power rating,

Amazon product ASIN B01E74TEPG
not sure if some of the other above are better but least you can try for a week with Amazon and return

 

[GeorgeC]

To calibrate a digital probe thermometer it is usual to test at 0C and 100C. There are machines that will do temperatures in between to are costly.

Tests are as simple as melting ice [0C] and boiling water [100C].

Those dial thermometers are frankly shite and deserve to be placed in the bin and to be honest cheap probe thermometers are really no better.

To test a fridge's temperature it is best to do so in circa 3 places to check more accurately. Fridges with fans have a better chance of consistent temperature throughout, commercial fridges are a case in point.