Ian_m wrote:
"John" wrote in message
...
We got a new freezer - it's a John Lewis Frost-Free job. We keep it in

//snip//


Correct, my mates fridge/freezer in his outside shed, defrosts the freezer
when the temperature drops below about 5°C. This is because the compressor
no longer runs as it thinks the fridge is cold enough ie below 5°C. It does
state a minimum of +15°C so he wasn't too surprised. So after piddling
around with a 100W tube heater set to 5°C and getting variable results he
moved it back indoors where it now works perfectly.

If you shop around you can get fridges and freezer that do work at lower
temperatures but tend to be commercial models with commercial price tags.

This problem reared its head when shopping for a replacement chest
freezer [no fridge] 3 years ago or so. There was a big sign up in the
elec section of a dept store saying none of their freezers were
suitable for outside use.

I didn't believe it but after some querying & searching about, it did
indeed turn out that there are 2 types of freezer - ones which work at
any ambient & ones which need a minimum temp. We found Iceland sold
some (at least over the web) which were suitable for outside use - NB
that was 3 years ago. It is just possible the more expensive ones
don't have this problem.

I didn't discover the reason, but there were suggestions that it was
due to the change from CFC gases. Some replacement gases - no doubt
the cheaper ones - apparently forced this limitation. OTOH it could
simply be that some freezer control systems cannot deal with temp
inversion (or it could be both reasons).

Long ago we had a plain fridge which didn't like temp inversion, so it
didn't work overnight in midwinter - that was before CH came our way.
But there's quite a number of other operational conditions in practical
refrigeration cycles which defeat the assumption 'colder is better'.
One I've seen in a southern Europe in a hot summer was due to ice
formation due to the fridge/freezer running too long. Ice is a thermal
insulator, which if it forms & doesn't have a chance to melt/evaporate,
stops the thermostat sensing the correct temp & so the fridge never
stops running, forming more ice over the thermostat....etc etc.

BTW SFAIUI in fridge a temperature control is applied to the freezing
section & the rest of the fridg is cooled relatively. So the temp in
the ice box is the key factor, not the temp in the fridg itself.

Good news is that the freezer we have that seemed to be failing 3 years
ago is still going :-))