Freezer temperature Q.

Recommended setting for a freezer is -18C IIRC

I concur - though I set mine to -24 (and it *can* go to -36C! if you max it out)

If its a fridge as well, it may well be that part that is keeping it running. Brian

-18 is the usual. They vary a few degrees in practice

NT

Bought a new freezer (standalone, under the counter) recently; it has a temperature display/control on the front. I wanted to check the temps, as no point in having it over cold as I was aiming for -18. I have a thermometer with a small digital display and a long wire with a sensor on the end so I can put the sensor inside and the display outside and can check the temps without having to open the door all the time (counter-productive!).

I found that I had to set the display control on the front to -15 to get the temps (according to the probe thermometer) to be near -18 otherwise the freezer was setting itself far too cold and using far too much electricity...

Just my 2p's worth.

Couldn't you have just bought one in a shop? There are are no restrictions on the sale of freezers that I'm aware of. :oD

What did you check the thermometer against? IME cheap digital thermometers can be a few degrees out.

I think you can check it by putting a load of ice in brine + some extra salt as the ice dilutes it as it melts, in equilibrium it should be around -20C.

I think you have in mind that a saturated salt solution freezes at -21.1 degrees. It's a simple test to see if a freezer is well below -18.

You can get a solution that freezes at -18 degrees by weighing carefully the salt and water but I don't have the ratio to hand.

Thanks for all the replies ...

It's just a freezer - not a fridge freezer.

I was testing it will a little digital thermometer used for checking aquarium temperatures.

Eventually, it got to -25, still running. But next morning, it was -19, and had stopped. It spent yesterday ping ponging between -9 when the door was opened, to -21. Currently at ... -20.

But yesterday the temperature in the house dropped a couple of degrees, which means it's able to lose heat slightly better ...

Main concern is that it;s at least 16 years old .... it was here when we moved in.

What do these ice-breaker fish look like?

If the freezer only has air in it, the temperature will change pretty rapidly when the door is open ..

Yup. It sounds serviceable, most likely.

NT

-18C is warmest a 3-star Freezer is allowed to run. Usually, they are at least a little bit colder, baring in mind the temperature is unlikely to be completely uniform throughout.

I accidently left my Hotpoint on fast freeze for a few days when it was quite new. It went below -40C (how much below I don't know). The thermometer had sucked all the liquid back into the bulb, and the lowest marking on the scale before that was -40C.

====snip====

That is the one temperature where the use of C or F is redundant. You could have simplified it to "-40" and let the reader choose their preferred scale. :-)

I hate it when newspapers say "the mercury dropped to below -50". Mercury freezes before -40 ...

Mercury hasn't been used in thermometers for *years* ....

Well, that too.

Another mindless literalist. Get your carer to explain "metonymy" to you.

That applies to new ones, but plenty of mercury ones still exist.

Another mindless poster who can't quote.