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Default Freezers: keep warm or keep cold?

We got a new freezer - it's a John Lewis Frost-Free job. We keep it in
the utility. When my wife told the salesman this, he asked about the
ambient temperature of the room (which is very cool, not to say cold.)

He seemed to imply it would be better if the room that the freezer is
kept in should be warmer rather than colder. This doesn't seem to make
sense to me.

I wasn't there, and I figure it is more useful to get a consensus here
than go back and ask a random salesman in a shop (even if it is John
Lewis).

The instructions for the freezer aren't a lot of help (produced in the
same country the freezer was made: very terse as well as poor English).
However it does state preferred ambient temperature ranges ... all I
have to do is find the serial number plate to find out which grade ours
is -- I am suspecting the plate is underneath the damn thing, having
failed to find it on the back.


ANYWAY: what's the story? I would have thought that the colder the
room, the better. The thing is: this freezer seems to be running its
condenser quite as much as our ancient thing, that we swopped it for.

Cheers
John
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Default Freezers: keep warm or keep cold?

John wrote:
We got a new freezer - it's a John Lewis Frost-Free job. We keep it in
the utility. When my wife told the salesman this, he asked about the
ambient temperature of the room (which is very cool, not to say cold.)

He seemed to imply it would be better if the room that the freezer is
kept in should be warmer rather than colder. This doesn't seem to make
sense to me.


The salesman is wrong. The colder the air is around the radiator, the
less work the motor has to do to keep the food at the same cold
temperature.

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Default Freezers: keep warm or keep cold?

John wrote:
We got a new freezer - it's a John Lewis Frost-Free job. We keep it in
the utility. When my wife told the salesman this, he asked about the
ambient temperature of the room (which is very cool, not to say cold.)

He seemed to imply it would be better if the room that the freezer is
kept in should be warmer rather than colder. This doesn't seem to make
sense to me.

I wasn't there, and I figure it is more useful to get a consensus here
than go back and ask a random salesman in a shop (even if it is John
Lewis).

The instructions for the freezer aren't a lot of help (produced in the
same country the freezer was made: very terse as well as poor English).
However it does state preferred ambient temperature ranges ... all I
have to do is find the serial number plate to find out which grade ours
is -- I am suspecting the plate is underneath the damn thing, having
failed to find it on the back.


ANYWAY: what's the story? I would have thought that the colder the
room, the better. The thing is: this freezer seems to be running its
condenser quite as much as our ancient thing, that we swopped it for.

Cheers
John


It's b....locks. The physics is easy. A freezer is a heat pump, it
pumps heat from the inside to the outside. The cooler the outside is
the less energy is required to attain the correct temperature inside.

Other considerations: The running temperature of the pump - better in a
lower temperature as long as any grease used in the bearings doesn't
freeze (no liquid nitrogen in your utility is there?).

The working fluid (Ammonia usually) doesn't freeze, or fail to
evaporate. (Only a problem in the Outer Planets, and certainly not your
utility room)

R.
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Default Freezers: keep warm or keep cold?


Keep it in a cool place. Not only will the condenser be able to dump
heat easier in a lower ambient temperature, but the heat energy passing
into the freezer from the surrounding air in the first place will be
reduced as well.

Frost-free freezers are less efficient than ones that have to be
manually defrosted. Ours has a heater element (about 300 watts) that
runs round the evaporator (the bit that cools the air inside the
freezer). Every eight hours or so the compressor switches off and the
heater is turned on for a few minutes. This melts the ice build-up on
the evaporator which then drains away through a pipe into a tray on top
of the compressor from where it naturally evaporates. Because the
heater is part of the evaporator assembly and is inside the freezer
compartment, inevitably that extra energy (300 watts for a few minutes
three times a day) than has to be removed when the compressor switches
back on again at the end of the defrost cycle.

Mike

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Default Freezers: keep warm or keep cold?

Some freezers will not work if kept in a very cold (less than around
4°C??). There have been cases of people replacing old freezers in
outhouses, where it gets very cold in winter, with newer freezers which
have a minimum temp requirement, and the freezers not working. Check
the instructions of phone the manufacturer.


MikeH wrote:
Keep it in a cool place. Not only will the condenser be able to dump
heat easier in a lower ambient temperature, but the heat energy passing
into the freezer from the surrounding air in the first place will be
reduced as well.

Frost-free freezers are less efficient than ones that have to be
manually defrosted. Ours has a heater element (about 300 watts) that
runs round the evaporator (the bit that cools the air inside the
freezer). Every eight hours or so the compressor switches off and the
heater is turned on for a few minutes. This melts the ice build-up on
the evaporator which then drains away through a pipe into a tray on top
of the compressor from where it naturally evaporates. Because the
heater is part of the evaporator assembly and is inside the freezer
compartment, inevitably that extra energy (300 watts for a few minutes
three times a day) than has to be removed when the compressor switches
back on again at the end of the defrost cycle.

Mike




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Default Freezers: keep warm or keep cold?

The message
from John contains these words:

He seemed to imply it would be better if the room that the freezer is
kept in should be warmer rather than colder. This doesn't seem to make
sense to me.


Nor should it. The device is trying to shove heat out the back - the
cooler the surroundings the easier this is. The warmer the surroundings
the harder it has to try - and use more power in the process.

The only gotcha is that some fridge-freezers only have one thermostat
and that's in the fridge bit. If the ambient is below the set-point for
the thermostat in the fridge it'll never switch on so the freezer bit
will never get cooled as it operates as a side-show to the fridge. But
that doesn't appear to be the case in your situation.

Whichever course you take, ensure there's good airflow over the back of
the unit - don't pile the top up with stuff that goes back to the wall,
and don't block round the sides/bottom.

--
Skipweasel
Pay no attention to that man behind the curtain.
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Default Freezers: keep warm or keep cold?

MikeH wrote:
Keep it in a cool place. Not only will the condenser be able to dump
heat easier in a lower ambient temperature, but the heat energy passing
into the freezer from the surrounding air in the first place will be
reduced as well.


I'd follow the manufacturers recommendations over bar-room science.
Fridges and freezers *do* have specific operating temperatures, and
it's fairly well known that fridges in particular can struggle in a
very cold environment. Freezers should have more leeway as they are
cooling to a much lower temperatures.

Frost-free freezers are less efficient than ones that have to be
manually defrosted. Ours has a heater element (about 300 watts) that
runs round the evaporator (the bit that cools the air inside the
freezer). Every eight hours or so the compressor switches off and the
heater is turned on for a few minutes. This melts the ice build-up on
the evaporator which then drains away through a pipe into a tray on top
of the compressor from where it naturally evaporates. Because the
heater is part of the evaporator assembly and is inside the freezer
compartment, inevitably that extra energy (300 watts for a few minutes
three times a day) than has to be removed when the compressor switches
back on again at the end of the defrost cycle.


How inefficient is a badly frosted-up unit, though? Generally, they
start to cut in more and more often to less and less effect as the
plates freeze up.

--
"Spice is the variety of life."

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Default Freezers: keep warm or keep cold?

John wrote:

We got a new freezer - it's a John Lewis Frost-Free job. We keep it
in
the utility. When my wife told the salesman this, he asked about the
ambient temperature of the room (which is very cool, not to say cold.)

He seemed to imply it would be better if the room that the freezer is
kept in should be warmer rather than colder. This doesn't seem to
make sense to me.

I wasn't there, and I figure it is more useful to get a consensus here
than go back and ask a random salesman in a shop (even if it is John
Lewis).

The instructions for the freezer aren't a lot of help (produced in the
same country the freezer was made: very terse as well as poor
English). However it does state preferred ambient temperature ranges
... all I have to do is find the serial number plate to find out which
grade ours is -- I am suspecting the plate is underneath the damn
thing, having failed to find it on the back.


ANYWAY: what's the story? I would have thought that the colder the
room, the better. The thing is: this freezer seems to be running its
condenser quite as much as our ancient thing, that we swopped it for.

Cheers
John


I asked a similar question here over a year ago just after I bought a
new freezer. In the manual my new Frigidaire said it needs a minimum
ambient temperature of 16degC. I was very cross - and still am - with
Currys for not telling me this before I bought it and then for refusing
to take it back without a large surcharge.

I think there are two reasons:

First some fridge/freezers use only one mechanism to work both parts. If
the machine doesn't run enough one part remains cold while the other
part gradually defrosts and the food rots. Or something like that.

Secondly cold ambient encourages condensation inside the freezer case
but outside the main storage compartment. This either rusts the machine
or builds up into a large block of ice underneath which never seems to
get melted.

With some encouragement here I mended the old freezer and now use both
freezers on the approach to Christmas then switch off the Frigidaire
until the spring when I swap over. (I'm fortunate to have the space to
keep two freezers.) This allows both freezers to get a really thorough
defrost each year.

In my old Hotpoint the block of ice in its innards took a very long time
to completely defrost and dry out. Not days but weeks in summer.

Edgar


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Default Freezers: keep warm or keep cold?

On Mon, 04 Sep 2006 09:52:09 +0100, John wrote:

However it does state preferred ambient temperature ranges ... all I
have to do is find the serial number plate to find out which grade ours
is -- I am suspecting the plate is underneath the damn thing, having
failed to find it on the back.


Looked inside it? That is where it is for our fridge and fridge/freezers.

ANYWAY: what's the story? I would have thought that the colder the
room, the better. The thing is: this freezer seems to be running its
condenser quite as much as our ancient thing, that we swopped it for.


Is it cooling to the same, measured, temperature or lower?

There is information on the web about why fridges and freezers have a
designed ambient temperature range. Have a dig for the facts rather than
the unsupported guff already posted. For single compressor
fridge/freezers it is a very real issue as the freezer is part only
cooled when the fridge wants cooling. With a low ambient temp the heat
gain in the fridge will be longer than designed and thus the freezer will
also warm up, possibly above "safe" levels.

--
Cheers
Dave. pam is missing e-mail



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Default Freezers: keep warm or keep cold?

On Mon, 04 Sep 2006 09:52:09 +0100, John wrote:

We got a new freezer - it's a John Lewis Frost-Free job. We keep it in
the utility. When my wife told the salesman this, he asked about the
ambient temperature of the room (which is very cool, not to say cold.)

He seemed to imply it would be better if the room that the freezer is
kept in should be warmer rather than colder. This doesn't seem to make
sense to me.

I wasn't there, and I figure it is more useful to get a consensus here
than go back and ask a random salesman in a shop (even if it is John
Lewis).

The instructions for the freezer aren't a lot of help (produced in the
same country the freezer was made: very terse as well as poor English).
However it does state preferred ambient temperature ranges ... all I
have to do is find the serial number plate to find out which grade ours
is -- I am suspecting the plate is underneath the damn thing, having
failed to find it on the back.


ANYWAY: what's the story? I would have thought that the colder the
room, the better. The thing is: this freezer seems to be running its
condenser quite as much as our ancient thing, that we swopped it for.

Cheers
John


A week or so ago Will Dean gave a respose to thread "freezer operation
at low ambiant temp"

"I suspect that one reason for the caution about extreme temperatures
is that
domestic fridges/freezers use a capiliary tube as an expansion device,
rather than the more sophisticated thermostatic devices used in
commercial
plant. Because the capiliary is just a fixed flow restriction rather
than a
proper temperature/pressure regulator, it's specified on the basis of
fairly
narrowly constrained pressure/temperature conditions throughout the
plant.

A very cold condenser will give low high-side pressures which might be
outside those for which the capiliary was designed - it can also cause
an
excessive proportion of the charge to hang around within the
condenser.

All they're really saying in the instructions is that they designed
the
freezer to perform to specification with a certain external
temperature
range, and that outside that range it may not meet the spec."


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Default Freezers: keep warm or keep cold?

Coo - what a great set of answers -- thanks a lot chaps (don't think
there were any chapesses there).

Also:
In article ,
marvelus wrote:

A week or so ago Will Dean gave a respose to thread "freezer operation
at low ambient temp"


ACH! So he did! I forgot to Google Groups for 'freezer' before I
posted: my sincere apologies (though I think I've got answers more
suited to my simpler mind).

Cheers
John
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Default Freezers: keep warm or keep cold?

"John" wrote in message
...
We got a new freezer - it's a John Lewis Frost-Free job. We keep it in
the utility. When my wife told the salesman this, he asked about the
ambient temperature of the room (which is very cool, not to say cold.)

He seemed to imply it would be better if the room that the freezer is
kept in should be warmer rather than colder. This doesn't seem to make
sense to me.

I wasn't there, and I figure it is more useful to get a consensus here
than go back and ask a random salesman in a shop (even if it is John
Lewis).

The instructions for the freezer aren't a lot of help (produced in the
same country the freezer was made: very terse as well as poor English).
However it does state preferred ambient temperature ranges ... all I
have to do is find the serial number plate to find out which grade ours
is -- I am suspecting the plate is underneath the damn thing, having
failed to find it on the back.


ANYWAY: what's the story? I would have thought that the colder the
room, the better. The thing is: this freezer seems to be running its
condenser quite as much as our ancient thing, that we swopped it for.


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.


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In article ,
Richard Downing writes:
It's b....locks. The physics is easy. A freezer is a heat pump, it
pumps heat from the inside to the outside. The cooler the outside is
the less energy is required to attain the correct temperature inside.


The engineering is not so easy though. Units are somewhat
constrained on temperature range they can cover, so they
are designed to cover the most common temperature range in
a home, i.e. 16-35C.

Other considerations: The running temperature of the pump - better in a
lower temperature as long as any grease used in the bearings doesn't
freeze (no liquid nitrogen in your utility is there?).


Pumps usually outlast a freezer at normal ambient temperatures,
so there's not much to be gained trying to make one last longer.

The working fluid (Ammonia usually) doesn't freeze, or fail to
evaporate. (Only a problem in the Outer Planets, and certainly not your
utility room)


Ammonia hasn't been used in domestic fridges or freezers for over
50 years (except adsorption fridges). It is still used in some
very large industrial fridges and freezers.

--
Andrew Gabriel
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"Matty F" wrote in message
ps.com...
John wrote:
We got a new freezer - it's a John Lewis Frost-Free job. We keep it in
the utility. When my wife told the salesman this, he asked about the
ambient temperature of the room (which is very cool, not to say cold.)

He seemed to imply it would be better if the room that the freezer is
kept in should be warmer rather than colder. This doesn't seem to make
sense to me.



Salesman is probably correct. I'd suggest you try to keep within the ambient
range of temperatures which will be mentioned in the instructions.
Alternatively you could try and find out the exact refrigerant used by the
freezer and work out what the minimum temp will be based on Pressure and
type. Some fridges these days use R134a, which has a boiling point of -26
deg C at atmospheric temp and 5 - 10 deg C when under pressure in a Fridge,
hence the minimum 15 deg ambiant temperature requirement to ensure the
refridgerant vaporises when it leaves the freezer compartment.


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The message
from "L Reid" contains these words:

hence the minimum 15 deg ambiant temperature requirement to ensure the
refridgerant vaporises when it leaves the freezer compartment.


The refrigerant is supposed to evaporate inside the cold compartment -
that's how they work. The refrigerant draws the energy needed to go from
liquid to gas from the heat in the bit you're trying to cool.

If you were to evaporate the liquid elsewhere you'd get lumps of ice
forming outside the compartment at whatever point it's mistakenly doing
it.

--
Skipweasel
Pay no attention to that man behind the curtain.


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Default Freezers: keep warm or keep cold?


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 :-))

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L Reid wrote:

Salesman is probably correct. I'd suggest you try to keep within the ambient
range of temperatures which will be mentioned in the instructions.


I am sorry that I butted in. I never considered such low temperatures
outside. It's not a problem here in New Zealand, where I grow tomatoes
outdoors in winter.

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Hi,

I think the problem is that if the temp difference between condenser
and evaporator is too low for too long (low 'superheat'), there's a
chance liquid refrigerant will get back to the compressor, and jam it
or at least reduce it's life expectancy.

At a best guess, this is because the condenser and compressor
condenses refrigerant more efficiently at low ambient temps and so the
pressure in the evaporator rises.

As the pressure rises so does the boiling point of the refrigerant,
until it's too high to evaporate, and liquid refrigerant gets back to
the compressor.

One way round it might be to time the run time of the compressor at
say 5°C, then when it gets colder add _some_ insulation to the
condenser to trap heat and raise it's operating temperature.

As long as the run time at lower temps then stays above this figure,
it implies the condenser is working at a high enough temperature due
to the insulation.

With the old style black finned condenser, just adding some
polystyrene to the outside and leaving the inside free may be enough.

A more elegant solution would be making an insulated box around the
condenser ventilated by a thermostatically controlled fan

Needless to say, no responsibility accepted if anyone blows up their
freezer doing the above!

The forum at www.refrigeration-engineer.com would be a better place
to get a definitive answer.

cheers,
Pete.
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