How to measure fridge temperature

[theflash]

I have a Leibherr CNES 3556 fridge freeezer (bought in the last few days on the kind advice of this forum).

The unit appears very well made, however I have some concern over the temperatures in the fridge and wonder if I am measuring them correctly.

[This fridge freezer has a display on the front showing the ‘actual’ temperatures in the fridge and the freezer. The do state the the fridge temperature is an ‘average’ temperature (average of what?!).]

The fridge display is currently set at 2 degrees Celcius. However, our max-min digital thermometer says that its 4.9 degrees in the coolest part at the bottom and 6.0 at the top. It also says that the coolest part reached a max of 6 degrees overnight, and the top part 9-10 degrees(!).

[This design does not share cool air with the freezer, but using its own cool air (though uses only one compressor).]

My question therefore is:
Am I using the correct method to check the temperature?
My thermometer changes within seconds when the air temperature changes in the unit. The fridges built-in thermometer seems to be much much slower at noticing any change.

How can I tell if my food would be safe?

[theflash]

Re: How to measure fridge temperature

The engineer said that out digital thermometer should be about as sensitive as the built in one, and so the appliance must be faulty.

But I’ve read that you may have to put a thermometer in a glass to test the core temperature as opposed to the air temperature.

Can anyone help?

[admin]

Re: How to measure fridge temperature

Hi

Yes the correct way to get the correct reading is within a glass of water which has been in a closed compartment for 24 hrs.

Easier way to see if your fridge is cold enough is to put a glass bottle of fluid( Beer ) on the middle shelf in the middle.

after 24 hours or 2 nights take the bottle out and if its damp(condensation ) after a minute or so then it would be around the correct temprature.

Bryan

[theflash]

Re: How to measure fridge temperature

So am I right in assuming that generally these built in thermometers are basically in some sort of fluid themselves, or perhaps their sampling frequency is quite spread out?

It doesn’t change unless you keep the door open for about 15 minutes, and then only by one/two degrees.

and PS does it matter if the glass is not ‘glass’ ? (I put a plastic one in there an hour ago and I’m going to buy a thermometer to drop in it).

[Dales-Electronic]

Re: How to measure fridge temperature

This is another method that is used within the trade. Get a block of lard and place it in the fridge. After about 12 hours stick you temperature probe into the lard and measure its core temp – after all its the temperature of the product that is important not the air temp.

[theflash]

Re: How to measure fridge temperature

Thanks. The thermometer in water method is already showing some interesting results. At the moment (and I’ve got to leave it a few more hours) its showing exactly the same temperature as on the door display (which is what I wanted).

What puzzles me is why the manufacturers (Leibherr – or in this case the UK company that operates on their behalf) immediately suggested the appliance may be faulty, instead of suggesting the water/lard(!) method?

Is there a technical name for the type of sensor in these fridges that measures the ‘core’ temperature rather than the air temperature?

[kwatt]

Re: How to measure fridge temperature

No, they generally will use an average of the range which is what the core temperature is showing you, it’s the mean temperature that is the key.

Think on it this way, if the lowest temp is 2ËšC and the upper is 6ËšC then the average, all things being equal, is going to lie around 4ËšC pretty much all the time.

The thing is that, manually trying to log it when you can with a not too accurate thermometer you chuck in the fridge is not going to be anywhere near as accurate as the electronics of the machine itself. The only way to be absolutely sure is to log the temperature over a period of time, plot it on a graph and then calculate the average from the range. Of course this is impractical for most people.

The tricks described are our way of getting round that and obtaining an almost instant result in the field without having expensive kit hooked up to a machine for 24-48 hours at least. 😉

K.

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