Another article to pore over before it goes up....


NT



Most people now have a fridge freezer as their main machine, but
fridges are still useful for supplemental space.

A lot of the information here also applies to fridge freezers.


==Larders & frost free fridges==
Standard fridges have an icebox, which will ice up and require
periodic defrosting.

Larders contain no icebox, and don't frost up, so are frost free.


==Brands==
Pretty much all brands of fridge have a good reliability record. (This
is less true of fridge freezers.) Liebherr and Miele are generally
reckoned to be among the best makes.


==Faults==
Fridge faults can be caused by external factors.

Damp and [[water]] splash cause case rusting.

Liquid oozes inside the fridge can penetrate interior lining junctions
and saturate the [[insulation]] at the bottom, leading to external
dripping, rusting, increased power consumption and sometimes smells.

===Inadequate ventilation===
Too high a temp at the rear causes overheating of compressor, with
consequently much reduced life.

An indoor/outdoor thermometer can be used to tell if the temp behind
the fridge is getting too high, but its generally quicker to just
place a hand on the hext exchanger at the rear. Warmth is to be
expected, and hotness at one end, but if its hot all over then the
compressor isn't getting the cooling it needs. In this situation, the
refrigerant gas is delivered to the expansion line hot, so energy
consumption increases, further increasing average compressor temp and
reducing life expectancy.

The solution is more ventilation. Where its problematic to provide
this, a quiet 3" or 4" fan can be used to move air upwards behind the
machine.

===Dripping===
Modern fridges route interior condensation on the cooling plate down a
pipe to a plastic tray on the compressor. The [[water]] evaporates
from this due to the heat.

Exterior dripping can be caused by the drainage tube becoming
unattached from the plastic tray on the compressor.

Interior dripping can be caused by blockage of the entry point of the
pipe. Removal of any debris and a poke with a bit of [[Iron wire|
wire]] should clear this. If it blocks repeatedly, mould growth is the
usual culprit. This can usually be stopped by cleaning the interior
spotlessly.

Exterior dripping can also be caused by saturated [[insulation]].
Replacing the insulation is the only cure, which isn't worthwhile
unless the appliance is of high value. Insulation saturation usually
occurs at the bottom of the fridge.


===Smells===
Smelly fridges are usually sorted out with a thorough clean. Do not
use bleach or any scented cleaner.

If the fridge is in such a state that stinking oozes have gotten into
the [[insulation]], nothing but a new fridge will remedy this. For a
valuable fridge, replacement of the insulation is the solution.

===Thermostat===
A thermostat stuck off will make the fridge play dead. If stuck on,
the compressor will run all the time, consuming excessive energy.

Thermostats can be DIY replaced, but its not worth it for the average
fridge. The capillary tube on the stat usually passes through the
fridge's [[insulation]], and the whole assembly must go in without
being cut. The old one can be cut if necessary, as it doesn't need to
work again. Generic replacement stats are available.

===Compressor runs but not cold===
This is caused by loss of refrigerant, which is caused by a leak. A
gas refill will only leak out again.

===Compressor dead===
Compressors can be replaced, but again most fridges aren't worth it.

===Partial short===
A compressor with a partial short will overheat very quickly and cut
out. Or it may blow [[fuse]]s. Its posible to make these run by adding
a high power series resistance to limit the short current, but the
increased energy consumption and low cost of replacement fridges makes
it not usually worthwhile. A 240v 3kW heater makes a suitable series
resistance.

===Noise===
Fridge noise is usually caused by something touching the compressor or
failure of the rubber suspension under the compressor. The latter can
be fixed by inserting chunks of rubber under the compressor, making
sure it can still move slightly.

===Refrigerant loss===
When a gas leak occurs, repairers may offer to refill. However if it
leaked out once, it will do so again, so this will only ever be a
temporary repair. Locating a very slow leak to fix it is extremely
difficult.

The situation is different with belt driven in-car compressors. These
leak refrigerant as a normal part of operation, and eventually require
refill.

===Seal damage===
Door seals can be replaced. Peel the seal back to locate the screws.


==Cleaning==
Be sure to avoid all scented cleaners. Avoid [[Scraper|scourers]]
which will make the interior lining harder to clean in future. Avoid
bleach too. Cream cleaner and a cloth are normally effective, with a
brush for any residue buildup. Stubborn dirt should be soaked to
loosen.


==Storage==
Unused fridges should be stored with door ajar to avoid bad odours.
When the door may get closed, placing a couple of clean dry teabags
inside will help.


==Cooling arrangements==
There are 3 common cooling arrangements:
# Heat exchanger at back. Requires rear ventilation, but no side
ventilation.
# No external heat exchanger. These have cooling tubes built in under
the outer skin, and require side ventilation for cooling.
# Less common is cooling underneath the fridge, with warm air expelled
at the front at the base. Such fridges require no ventilation to sides
or rear.


==Side gap==
Its traditional to leave a small gap each side of a fridge. This gap
makes moving the appliance easier, avoids the door catching, avoids
vibration noise and increases rear ventilation. Newer fridges with no
external heat exchanger need side ventilation for cooling.


==Wire vs glass shelves==
Glass shelves are wipe cleanable, and minimise spills of meat juices
etc onto foods below.
Glass and wire are both dishwashable.

Glass shelves can't always be retrofitted into a wire shelved fridge.
Glass blocks air circulation, and this can sometimes result in
inadequate cooling in fridges designed for wire. If retrofitting
you'll need to check the temp on each shelf afterwards.


==Energy efficiency==
The energy efficiency of fridges has improved substantially since the
1970s. A free 70s fridge will generally cost more in total over its
lifetime than a new one.


==Refrigerants==
Until recently nearly all fridges used the CFC R12, also known as
freon. New fridges use any of several HC and HFC refrigerants. Some of
these are believed to affect the ozone layer as well, some not.

===Propane===
Fridges in third world countries normally use propane (or similar
gases) as the refrigerant. These gases are cheap and efficient, but
leaks are potentially explosive. Despite this, data indicates that
real world risk is negligible. A very few fridges here also use such
gases, and with these one should ventilate well if gas is smelt.

Propane is also sometimes used by DIYers to repair fridges and a/c
systems that were designed for R12, R-22 or R-134a. Its cheap, readily
available, a plug-in replacement, and 9-15% more energy efficient than
R12, but its also highly flammable.

Propane refrigerant is labelled as R-290. Note that bottled propane is
a propane butane mix, not pure propane.

Butane is R-600 and works at low enough pressure to be contained in
reinforced plastic hose.

Pentane is another low working pressure refrigerant gas.


===Ammonia===
Ammonia has long been used in a small percentage of fridges using the
ammonia absorption cycle. These fridges are almost totally silent,
with just the thermostat's click and the occasional quiet gurgle. They
are easily spotted:
* the equipment on the rear looks quite different to compressor
fridges
* They are completely silent when first plugged in

There are 2 issues with these fridges.
# Power consumption is relatively high, due to low thermal efficiency
# Even a mini fridge contains over 1kg of ammonia, which would be
fatal if released.

The advantage of these fridges is they can in principle be run off any
source of heat, such as 240v, 12v or bottled gas. Hence they are
standard equipment in caravans.


==Antique fridges==
===R12===
Safe R12 refrigerant was introduced in the mid 1930s. Old fridges
using R12 and a sealed compressor unit will behave much like modern
fridges, albeit with relatively poor energy efficiency, and without
all the other modern refinements such as wipe clean linings, safe door
latches, even temperature, low noise level and so on.

===Belt drive===
Earlier fridges used a separate motor and belt driven compressor.
These are less efficient, and the compressor gradually leaks
refrigerant, so needs refilling in time. The belt can slip or break.

Some belt driven fridges didn't use R-12, and are a safety problem -
see below.

===Pre- R-12 fridges===
These all used a belt driven compressor, along with assorted nasty
refrigerants. Belt diven compressors leak gas as a normal part of
operation. The refrigerants used vary from toxic to very toxic, and
some are explosively flammable. Such fridges are not suitable for use
in inhabited spaces, and never were.

Refilling with modern refrigerants is problematic, as the working
pressures of these old systems are often too far removed from those of
modern equipment to produce a workable refrigeration cycle. Some of
the old refrigerants (eg SO2) are sufficiently safe to use if the
location is well ventilated and isolated from the main building. Some
are absolutely not.

Butane and pentane work with lower pressures than R12, and may be
usable in some cases. Ventilation is necessary when using a highly
flammable gas in a belt drive compressor.


==Peltiers==
New mini fridges usually use peltier heat pumps instead of the ammonia
absorption cycle. Like ammonia, these are silent and have poor energy
efficiency, but the very remote risk of ammonia release is not there.

These fridges don't generally have the same cooling power as standard
fridges, with the ability to only cool by upto 15°C being normal. Thus
they are not safe to use as a main fridge from a food poisoning point
of view, as food stored at 15°C in a hot 30°C room will spoil rapidly.
This is why they are usually described as drink chillers only. If
wanted to store food, the interior temp should be monitored and the
machine only used for foods requiring refrigeration when sufficiently
cool. Foods that don't require refrigeration (such as chocolate) are
safe to store in them.

The peltier pumps used in these are usually rated at 12v 5A, but can
run on anything upto 16v for maximum cooling. Some of these mini
fridges also have a fan or a second peltier, doubling power use.


==Temperatures==
5°C is the recommended fridge temp for food storage.

Temperatures in fridges tend to vary from one location to another. The
salad crisper operates at high RH and slightly higher temp, keeping
salads firm for longer and avoiding any risk of freeze damage.
Enclosed spaces mounted on the door also run at slightly higher temp,
and are good for keeping butter, making it not quite so hard.

Areas close to the cooling plate run colder, and foods such as salads
can be damaged by frost if put there.


==TCO==
Annual Total Cost of Ownership depends on purchase cost, life
expectancy and energy cost. Hence the most energy efficient models
aren't necessarily the best value ones, but are more likely to be if
all other factors are equal. Naturally all other factors aren't equal
in practice, since maximising energy efficiency costs money.

Life expectancy is an important factor when seeking to minimise TCO.

Having said all this, there is no single simple strategy to minimise
TCO, and no hard reliability or life expectancy data to base
calculations on. News:uk.d-i-y and expert websites sometimes discuss
TCO reduction strategies, but opinion remains divided.



==Food safety==
# Check the fridge temperature is correct.
# Inspect contents regularly, removing anything that is beginning to
spoil.
# Avoid arranging foods so that meat juices could drip onto other food
types.
# Keep the fridge interior clean.
# Glass shelves reduce cross contamination by reducing drips.



==Disposal==
Local councils usually take fridges and freezers away free. Local
dealers will purchase or collect the very few types of fridge they
could repair and sell profitably, but this only applies to high ticket
items.

Most other disposal options are now illegal for R12 fridges, since it
is no longer permitted to release R12 to the atmosphere.

===Compressors===
Compressors removed from fridges have their uses. They provide
compressed air at high pressure but low flow rate, and require an oil
catcher if they're to last.


==The dial==
Fridge dials are usually marked with numbers unrelated to actual
temperature. The only way to determine temperature is to leave a
thermometer in the fridge.

A few fridges also have an [[insulation]] sheet between icebox and the
main fridge space. The position of this can be adjusted in conjunction
with the thermostat dial to achieve the desired temperatures in both
fridge and icebox sections. The sheet is moved to adjust the relative
temps of fridge and icebox; when blocking all airflow there will be
maximum temp difference, and when opened there will be less temp
difference.


==Improving energy efficiency==
For most of us the simple way to improve energy efficiency is to
replace the 1980s fridge with a modern A rated one.

===Energy saver plugs===
Energy saver plugs reduce energy consumption in older fridges, but are
incompatible with a lot of new fridges, some of which have this
technology built in.

Energy saver plugs pass full power to the compressor during starting,
then throttle the power back once running.

In many places a 10 year old fridge can be bought for the price of one
of these plugs, and will deliver more performance improvement, so even
for older fridges their use isn't very popular.

===More aggressive methods===
People running fridges on small solar electric systems sometimes wish
to reduce energy consumption. Any of the folowing can help:
* Add more polystyrene [[insulation]] on the outside of the fridge
(watch for condensation on the metal cabinet, which can rust it)
* Use an energy saver plug when compatible
* Put frozen items in the fridge overnight when defrosting them
* Write contents on a wipe clean board on the front, then decisions
can be made with the door closed.


==See Also==
* [[Special:Allpages|Wiki Contents]]
* [[Special:Categories|Wiki Subject Categories]]
* [http://www.wou.edu/~avorder/Refrigeration.htm Refrigerant history]



[[Category:Appliances]]
[[Category:Cooling]]
[[Category:Fault Finding]]
[[Category:Energy Efficiency]]
[[Category:Cleaning]]
[[Category:Kitchens]]
[[Category:Repair]]

snip fridge article

I've only skimmed, but a couple of minor comments:

- You say recommended temperature for food storage is 5oC. Being pedantic
I thought it was 5oC or below (i.e. 4oC is also OK). Personally I don't
like the "taste" of milk at 5oC, and generally prefer stuff cold, so keep
my fridge a little cooler.

- I've seen people on here suggest a number of times that a frost free
fridge/freezer decreases the reliability. If there's evidence of this it
might be worth including in the article.

Piers

On Sun, 3 Aug 2008 18:17:04 -0700 (PDT), wrote:

===Smells===
Smelly fridges are usually sorted out with a thorough clean. Do not
use bleach or any scented cleaner.

If the fridge is in such a state that stinking oozes have gotten into
the [[insulation]], nothing but a new fridge will remedy this. For a
valuable fridge, replacement of the insulation is the solution.

Combine these two? By shifting the "Smells" out of the techy bits down to
the less techy cleaning and other information?

==Cleaning==
Be sure to avoid all scented cleaners. Avoid [[Scraper|scourers]]
which will make the interior lining harder to clean in future. Avoid
bleach too. Cream cleaner and a cloth are normally effective, with a
brush for any residue buildup. Stubborn dirt should be soaked to
loosen.

I've never used anything more than warm water and a cloth to clean a
fridge or freezer. Once clean dissolve some bicarbonate of soda in clean
water and wipe around all the inside with a clean cloth then just leave.
The bicarbonate is good at absorbing smells.

==Wire vs glass shelves==
Glass shelves are wipe cleanable, and minimise spills of meat juices
etc onto foods below.

Fresh meat should *never* be stored above other foods...

==Temperatures==
5°C is the recommended fridge temp for food storage.

5C or below but above 0C. B-)

==Disposal==
Local councils usually take fridges and freezers away free.

Ours doesn't.

"We offer a collection service for all electric appliances and cookers.
This includes all electric items that are larger than a small microwave
oven.

There is a special service for all electric appliances like; fridges,
freezers, televisions, cookers and computer monitors. A fixed charge of
£15.00 per item is required for this service."

http://www.eden.gov.uk/environment/r...ng/refuse-hous
ehold-waste-collection/refuse-electric-appliance-collection/

The only "free" service is if you take the items to one of the two
"houshold waste recycling centres".

Local dealers will purchase or collect the very few types of fridge they
could repair and sell profitably, but this only applies to high ticket
items.

IIRC a place selling fridges etc has to offer a collection of the old one
when they deliver the new. This may or may not be chargeable.

--
Cheers
Dave.

In message , Piers Finlayson
writes
snip fridge article

I've only skimmed, but a couple of minor comments:

- You say recommended temperature for food storage is 5oC. Being pedantic
I thought it was 5oC or below (i.e. 4oC is also OK). Personally I don't
like the "taste" of milk at 5oC, and generally prefer stuff cold, so keep
my fridge a little cooler.

- I've seen people on here suggest a number of times that a frost free
fridge/freezer decreases the reliability. If there's evidence of this it
might be worth including in the article.

Wasn't there also a thread on *location*, specifically whether a
conventional unit was suitable for use in an unheated environment such
as a garage.

regards

--
Tim Lamb

Various comments inline...

In article ,
writes:
Another article to pore over before it goes up....
NT
Most people now have a fridge freezer as their main machine, but
fridges are still useful for supplemental space.
A lot of the information here also applies to fridge freezers.
==Larders & frost free fridges==
Standard fridges have an icebox, which will ice up and require
periodic defrosting.
Larders contain no icebox, and don't frost up, so are frost free.
==Brands==
Pretty much all brands of fridge have a good reliability record. (This
is less true of fridge freezers.) Liebherr and Miele are generally
reckoned to be among the best makes.
==Faults==
Fridge faults can be caused by external factors.
Damp and [[water]] splash cause case rusting.
Liquid oozes inside the fridge can penetrate interior lining junctions
and saturate the [[insulation]] at the bottom, leading to external
dripping, rusting, increased power consumption and sometimes smells.
===Inadequate ventilation===
Too high a temp at the rear causes overheating of compressor, with
consequently much reduced life.

I'm not aware of any evidence for this statement. At higher
temperatures, the cooling effect reduces, eventually to nothing,
and this reduces the power output at the rear, so it's a somewhat
self-regulating effect on rear temperature. The significant factor
is that the fridge operating efficiency plummits, and interior will
get too warm in bad cases.

An indoor/outdoor thermometer can be used to tell if the temp behind
the fridge is getting too high, but its generally quicker to just
place a hand on the hext exchanger at the rear. Warmth is to be
expected, and hotness at one end, but if its hot all over then the
compressor isn't getting the cooling it needs. In this situation, the
refrigerant gas is delivered to the expansion line hot, so energy
consumption increases, further increasing average compressor temp and
reducing life expectancy.
The solution is more ventilation. Where its problematic to provide
this, a quiet 3" or 4" fan can be used to move air upwards behind the
machine.

Introducing forced air paths significantly increases the rate of
dust collection, and this can more than counter the forced cooling
after a while.

===Dripping===
Modern fridges route interior condensation on the cooling plate down a
pipe to a plastic tray on the compressor. The [[water]] evaporates
from this due to the heat.
Exterior dripping can be caused by the drainage tube becoming
unattached from the plastic tray on the compressor.

I've had a case where a metal tray rusted through doing this.
(It's now lined with aluminium foil.)

Interior dripping can be caused by blockage of the entry point of the
pipe. Removal of any debris and a poke with a bit of [[Iron wire|
wire]] should clear this. If it blocks repeatedly, mould growth is the
usual culprit. This can usually be stopped by cleaning the interior
spotlessly.
Exterior dripping can also be caused by saturated [[insulation]].
Replacing the insulation is the only cure, which isn't worthwhile
unless the appliance is of high value. Insulation saturation usually
occurs at the bottom of the fridge.
===Smells===
Smelly fridges are usually sorted out with a thorough clean. Do not
use bleach or any scented cleaner.

Sodium Bicarbonate dissolved in water is the most appropriate
fridge cleaner.

If the fridge is in such a state that stinking oozes have gotten into
the [[insulation]], nothing but a new fridge will remedy this. For a
valuable fridge, replacement of the insulation is the solution.
===Thermostat===
A thermostat stuck off will make the fridge play dead. If stuck on,
the compressor will run all the time, consuming excessive energy.

and permanently icing up the cold plate.

Thermostats can be DIY replaced, but its not worth it for the average
fridge. The capillary tube on the stat usually passes through the
fridge's [[insulation]], and the whole assembly must go in without
being cut. The old one can be cut if necessary, as it doesn't need to
work again. Generic replacement stats are available.
===Compressor runs but not cold===
This is caused by loss of refrigerant, which is caused by a leak. A
gas refill will only leak out again.
===Compressor dead===
Compressors can be replaced, but again most fridges aren't worth it.
===Partial short===
A compressor with a partial short will overheat very quickly and cut
out. Or it may blow [[fuse]]s. Its posible to make these run by adding
a high power series resistance to limit the short current, but the
increased energy consumption and low cost of replacement fridges makes
it not usually worthwhile. A 240v 3kW heater makes a suitable series
resistance.

I don't believe this would work. Fridge compressors have barely enough
power to start (they will fail to start sometimes - this is expected).
With a series resistance, the chance of starting failure is going to
be very much higher.

A compressor with a shorted turn has had it. Period.
It will run, but it will be drawing some kW's rather than 100W,
and will quickly trip its overcurrent circuit.

===Noise===
Fridge noise is usually caused by something touching the compressor or
failure of the rubber suspension under the compressor. The latter can
be fixed by inserting chunks of rubber under the compressor, making
sure it can still move slightly.
===Refrigerant loss===
When a gas leak occurs, repairers may offer to refill. However if it
leaked out once, it will do so again, so this will only ever be a
temporary repair. Locating a very slow leak to fix it is extremely
difficult.
The situation is different with belt driven in-car compressors. These
leak refrigerant as a normal part of operation, and eventually require
refill.
===Seal damage===

Test effectiveness of the door seal by checking it will grip a till
receipt all the way around. A failed seal will allow air to leak
through which will result in excessive condensation formation on
the cold plate, and reduction in efficiency.

If the seal looks OK but isn't sealing, check the fridge is standing
squarely and level on the floor with the feet adjusted correctly. The
cabinent is easily jarred when not supported correctly on all feet,
which can prevent the door fitting the frame. Secondly, check the door
adjustment (where present). This should be correct when supplied, but
might have been messed up by reversing the door and not setting it up
correctly.

Door seals can be replaced. Peel the seal back to locate the screws.

With many modern fridges, they can't anymore. The field replaceable
unit is the whole door.

==Cleaning==
Be sure to avoid all scented cleaners. Avoid [[Scraper|scourers]]
which will make the interior lining harder to clean in future. Avoid
bleach too. Cream cleaner and a cloth are normally effective, with a
brush for any residue buildup. Stubborn dirt should be soaked to
loosen.

Clean with just a sodium bicarbonate solution.
No pre-preprepared cleaners should be used.
If there's something stubborn which needs a powerful cleaner,
make sure you wash the cleaner off with sodium bicarbonate
afterwards.

==Storage==
Unused fridges should be stored with door ajar to avoid bad odours.
When the door may get closed, placing a couple of clean dry teabags
inside will help.

This is because most people won't be able to clean the fridge
interior well enough to get all the food contamination off, and it
will go moldy. If you can very thoroughly clean and dry it, then
you can close the door, just like a newly supplied fridge.

==Cooling arrangements==
There are 3 common cooling arrangements:
# Heat exchanger at back. Requires rear ventilation, but no side
ventilation.
# No external heat exchanger. These have cooling tubes built in under
the outer skin, and require side ventilation for cooling.
# Less common is cooling underneath the fridge, with warm air expelled
at the front at the base. Such fridges require no ventilation to sides
or rear.
==Side gap==
Its traditional to leave a small gap each side of a fridge. This gap
makes moving the appliance easier, avoids the door catching, avoids

There's also a condensation issue here. You need enough ventilation
at the sides to prevent the side panels dropping below the dewpoint
and generating condensation, which would run onto the floor. The
other alternative is to seal the side gap so there's no flow of air
to form condensation -- this is the approach used by linking kits
for linking adjacent appliances.

vibration noise and increases rear ventilation. Newer fridges with no
external heat exchanger need side ventilation for cooling.
==Wire vs glass shelves==
Glass shelves are wipe cleanable, and minimise spills of meat juices
etc onto foods below.
Glass and wire are both dishwashable.
Glass shelves can't always be retrofitted into a wire shelved fridge.
Glass blocks air circulation, and this can sometimes result in
inadequate cooling in fridges designed for wire. If retrofitting
you'll need to check the temp on each shelf afterwards.

Fridge interior design allows for the shelf types. You can't change
them restrospectively.

==Energy efficiency==
The energy efficiency of fridges has improved substantially since the
1970s. A free 70s fridge will generally cost more in total over its
lifetime than a new one.
==Refrigerants==
Until recently nearly all fridges used the CFC R12, also known as
freon. New fridges use any of several HC and HFC refrigerants. Some of
these are believed to affect the ozone layer as well, some not.
===Propane===
Fridges in third world countries normally use propane (or similar
gases) as the refrigerant. These gases are cheap and efficient, but
leaks are potentially explosive. Despite this, data indicates that
real world risk is negligible. A very few fridges here also use such
gases, and with these one should ventilate well if gas is smelt.
Propane is also sometimes used by DIYers to repair fridges and a/c
systems that were designed for R12, R-22 or R-134a. Its cheap, readily
available, a plug-in replacement, and 9-15% more energy efficient than
R12, but its also highly flammable.
Propane refrigerant is labelled as R-290. Note that bottled propane is
a propane butane mix, not pure propane.
Butane is R-600 and works at low enough pressure to be contained in
reinforced plastic hose.
Pentane is another low working pressure refrigerant gas.
===Ammonia===
Ammonia has long been used in a small percentage of fridges using the
ammonia absorption cycle. These fridges are almost totally silent,
with just the thermostat's click and the occasional quiet gurgle. They

This makes them the main choice for hotel room mini-bar fridges.

are easily spotted:
* the equipment on the rear looks quite different to compressor
fridges
* They are completely silent when first plugged in
There are 2 issues with these fridges.
# Power consumption is relatively high, due to low thermal efficiency
# Even a mini fridge contains over 1kg of ammonia, which would be
fatal if released.
The advantage of these fridges is they can in principle be run off any
source of heat, such as 240v, 12v or bottled gas. Hence they are
standard equipment in caravans.

Ammonia is also used as a refrigerant gas in giant (warehouse sized)
freezers (and maybe fridges).

==Antique fridges==
===R12===
Safe R12 refrigerant was introduced in the mid 1930s. Old fridges
using R12 and a sealed compressor unit will behave much like modern
fridges, albeit with relatively poor energy efficiency, and without
all the other modern refinements such as wipe clean linings, safe door
latches, even temperature, low noise level and so on.
===Belt drive===
Earlier fridges used a separate motor and belt driven compressor.
These are less efficient, and the compressor gradually leaks
refrigerant, so needs refilling in time. The belt can slip or break.
Some belt driven fridges didn't use R-12, and are a safety problem -
see below.
===Pre- R-12 fridges===
These all used a belt driven compressor, along with assorted nasty
refrigerants. Belt diven compressors leak gas as a normal part of
operation. The refrigerants used vary from toxic to very toxic, and
some are explosively flammable. Such fridges are not suitable for use
in inhabited spaces, and never were.
Refilling with modern refrigerants is problematic, as the working
pressures of these old systems are often too far removed from those of
modern equipment to produce a workable refrigeration cycle. Some of
the old refrigerants (eg SO2) are sufficiently safe to use if the
location is well ventilated and isolated from the main building. Some
are absolutely not.
Butane and pentane work with lower pressures than R12, and may be
usable in some cases. Ventilation is necessary when using a highly
flammable gas in a belt drive compressor.
==Peltiers==
New mini fridges usually use peltier heat pumps instead of the ammonia
absorption cycle. Like ammonia, these are silent and have poor energy
efficiency, but the very remote risk of ammonia release is not there.
These fridges don't generally have the same cooling power as standard
fridges, with the ability to only cool by upto 15°C being normal. Thus
they are not safe to use as a main fridge from a food poisoning point
of view, as food stored at 15°C in a hot 30°C room will spoil rapidly.
This is why they are usually described as drink chillers only. If
wanted to store food, the interior temp should be monitored and the
machine only used for foods requiring refrigeration when sufficiently
cool. Foods that don't require refrigeration (such as chocolate) are
safe to store in them.
The peltier pumps used in these are usually rated at 12v 5A, but can
run on anything upto 16v for maximum cooling. Some of these mini
fridges also have a fan or a second peltier, doubling power use.
==Temperatures==
5°C is the recommended fridge temp for food storage.

That should be "no more than 5"

Temperatures in fridges tend to vary from one location to another. The
salad crisper operates at high RH and slightly higher temp, keeping
salads firm for longer and avoiding any risk of freeze damage.
Enclosed spaces mounted on the door also run at slightly higher temp,
and are good for keeping butter, making it not quite so hard.
Areas close to the cooling plate run colder, and foods such as salads
can be damaged by frost if put there.

Overfilling a fridge or using loose food wrappings will prevent
airflow throughout the fridge and lead to uneven cooling, with
some areas freezing from time to time, and others never getting
cool enough to keep food safe.

==TCO==
Annual Total Cost of Ownership depends on purchase cost, life
expectancy and energy cost. Hence the most energy efficient models
aren't necessarily the best value ones, but are more likely to be if
all other factors are equal. Naturally all other factors aren't equal
in practice, since maximising energy efficiency costs money.
Life expectancy is an important factor when seeking to minimise TCO.
Having said all this, there is no single simple strategy to minimise
TCO, and no hard reliability or life expectancy data to base
calculations on. News:uk.d-i-y and expert websites sometimes discuss
TCO reduction strategies, but opinion remains divided.

Need to say something about fanned fridges here. Those parts are
significantly less reliable than the simple and well refined
compressor and sealed system, and you can expect to need some
repairs during the life of the fridge.

==Food safety==
# Check the fridge temperature is correct.
# Inspect contents regularly, removing anything that is beginning to
spoil.
# Avoid arranging foods so that meat juices could drip onto other food
types.
# Keep the fridge interior clean.
# Glass shelves reduce cross contamination by reducing drips.
==Disposal==
Local councils usually take fridges and freezers away free. Local
dealers will purchase or collect the very few types of fridge they
could repair and sell profitably, but this only applies to high ticket
items.
Most other disposal options are now illegal for R12 fridges, since it
is no longer permitted to release R12 to the atmosphere.

There's more CFC in the insulation of these fridges than there is
in the refrigerant. Whilst recovering the refrigerent is easy with
the right equipment, recovering the CFC from the insulation requires
large specialised plant, which is now a legal requirement across the
EU.

===Compressors===
Compressors removed from fridges have their uses. They provide
compressed air at high pressure but low flow rate, and require an oil
catcher if they're to last.
==The dial==
Fridge dials are usually marked with numbers unrelated to actual
temperature. The only way to determine temperature is to leave a
thermometer in the fridge.
A few fridges also have an [[insulation]] sheet between icebox and the
main fridge space. The position of this can be adjusted in conjunction
with the thermostat dial to achieve the desired temperatures in both
fridge and icebox sections. The sheet is moved to adjust the relative
temps of fridge and icebox; when blocking all airflow there will be
maximum temp difference, and when opened there will be less temp
difference.
==Improving energy efficiency==
For most of us the simple way to improve energy efficiency is to
replace the 1980s fridge with a modern A rated one.
===Energy saver plugs===
Energy saver plugs reduce energy consumption in older fridges, but are
incompatible with a lot of new fridges, some of which have this
technology built in.
Energy saver plugs pass full power to the compressor during starting,
then throttle the power back once running.
In many places a 10 year old fridge can be bought for the price of one
of these plugs, and will deliver more performance improvement, so even
for older fridges their use isn't very popular.
===More aggressive methods===
People running fridges on small solar electric systems sometimes wish
to reduce energy consumption. Any of the folowing can help:
* Add more polystyrene [[insulation]] on the outside of the fridge
(watch for condensation on the metal cabinet, which can rust it)
* Use an energy saver plug when compatible
* Put frozen items in the fridge overnight when defrosting them
* Write contents on a wipe clean board on the front, then decisions
can be made with the door closed.
==See Also==
* [[Special:Allpages|Wiki Contents]]
* [[Special:Categories|Wiki Subject Categories]]
* [http://www.wou.edu/~avorder/Refrigeration.htm Refrigerant history]
[[Category:Appliances]]
[[Category:Cooling]]
[[Category:Fault Finding]]
[[Category:Energy Efficiency]]
[[Category:Cleaning]]
[[Category:Kitchens]]
[[Category:Repair]]

You should consider running your fridge from a non-RCD protected
supply.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

===Partial short===
A compressor with a partial short will overheat very quickly and cut
out. Or it may blow [[fuse]]s. Its posible to make these run by adding
a high power series resistance to limit the short current, but the
increased energy consumption and low cost of replacement fridges makes
it not usually worthwhile. A 240v 3kW heater makes a suitable series
resistance.

===

This seems a bit over the top for most owners. Clutching at straws surely.

Andrew Gabriel coughed up some electrons that declared:

===Smells===
Smelly fridges are usually sorted out with a thorough clean. Do not
use bleach or any scented cleaner.

Sodium Bicarbonate dissolved in water is the most appropriate
fridge cleaner.

It's not well proven, based on a personal test case of one, but this is my
late mother's recommendation (she was in the catering management trade at
one time):

====
In the case of very bad smells in the plastics, mix up a large quantity of
Sodium Bicarbonate so as to form a paste with the consistency of icing.
Paint paste onto affected plastic thinly (but not too thinly, about 1mm is
OK). Leave to dry overnight. Brush and wash or hoover out.
====

Worked when I last had to use it where all previous methods had failed.
Might be worth including as a "if everything else has failed and you're
about to junk the appliance, try this".

Upto you all, just a suggestion.

Cheers

Tim

On Mon, 4 Aug 2008 09:54:31 +0100, Tim Lamb wrote:

Wasn't there also a thread on *location*, specifically whether a
conventional unit was suitable for use in an unheated environment such
as a garage.

Yes, well worth mentioning the "class" of the appliance. Fridges and
freezers are designed to work best within a range of ambient tempertaures.

The temp ranges and class is out there on the web somewhere.

--
Cheers
Dave.

===Thermostat===
A thermostat stuck off will make the fridge play dead. If stuck on,
the compressor will run all the time, consuming excessive energy.

Thermostats can be DIY replaced, but its not worth it for the average
fridge. The capillary tube on the stat usually passes through the
fridge's [[insulation]], and the whole assembly must go in without
being cut. The old one can be cut if necessary, as it doesn't need to
work again. Generic replacement stats are available.

I'm surprised you say it's not worth replacing. Under a tenner for a
generic one on eBay is a lot cheaper than a new fridge at several
hundred. But modern fridges with LED displays presumably use more
sophisticated thermostats which are not DIY-replaceable?

You might add that a temporary workaround for a thermostat stuck on
(or a bridged one stuck off) is to run the fridge off a timeswitch
programmed for (say) off 15mins of every hour.

==Disposal==
Local councils usually take fridges and freezers away free.

Ours doesn't either. It's £23.50 (low) or £45.50 (tall):
http://ebookings.bromley.gov.uk/bbs/...&c hild=&cid=
They even want £6 to take away a table lamp!

==Uses for a Dead Fridge==
There was a Gardener's World programme a year or so back that gave
suggestions for use of an old fridge carcase in the garden
(obviously). ISTR storing seeds, and on its back as a water butt.
Perhaps others can remember more. But I guess they involve letting the
gas out illegally (unless it's all leaked away already).

Chris

In article et,
"Dave Liquorice" writes:
On Mon, 4 Aug 2008 09:54:31 +0100, Tim Lamb wrote:

Wasn't there also a thread on *location*, specifically whether a
conventional unit was suitable for use in an unheated environment such
as a garage.

Yes, well worth mentioning the "class" of the appliance. Fridges and
freezers are designed to work best within a range of ambient tempertaures.

The temp ranges and class is out there on the web somewhere.

The main issue here were the older single compressor fridge/freezers
with a single thermostat in the fridge only (and they always have
the fridge at the bottom). If the room was cold enough not to require
much cooling for the fridge, the freezer would thaw out.

I don't think anyone makes these nowadays as technology has moved on
and it's now easy to have a single compressor drive a fridge and
freezer compartment independantly of each other, whereas this didn't
used to be the case.

The steel casework of white goods stored in a garage may start
rusting, as there's no waterproof layer in the paint finish.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

wrote:
Another article to pore over before it goes up....


NT



Most people now have a fridge freezer as their main machine, but
fridges are still useful for supplemental space.

A lot of the information here also applies to fridge freezers.


==Larders & frost free fridges==
Standard fridges have an icebox, which will ice up and require
periodic defrosting.

Larders contain no icebox, and don't frost up, so are frost free.


==Brands==
Pretty much all brands of fridge have a good reliability record. (This
is less true of fridge freezers.) Liebherr and Miele are generally
reckoned to be among the best makes.


==Faults==
Fridge faults can be caused by external factors.

Damp and [[water]] splash cause case rusting.

Liquid oozes inside the fridge can penetrate interior lining junctions
and saturate the [[insulation]] at the bottom, leading to external
dripping, rusting, increased power consumption and sometimes smells.

===Inadequate ventilation===
Too high a temp at the rear causes overheating of compressor, with
consequently much reduced life.

An indoor/outdoor thermometer can be used to tell if the temp behind
the fridge is getting too high, but its generally quicker to just
place a hand on the hext exchanger at the rear. Warmth is to be
expected, and hotness at one end, but if its hot all over then the
compressor isn't getting the cooling it needs. In this situation, the
refrigerant gas is delivered to the expansion line hot, so energy
consumption increases, further increasing average compressor temp and
reducing life expectancy.

The solution is more ventilation. Where its problematic to provide
this, a quiet 3" or 4" fan can be used to move air upwards behind the
machine.

===Dripping===
Modern fridges route interior condensation on the cooling plate down a
pipe to a plastic tray on the compressor. The [[water]] evaporates
from this due to the heat.

Exterior dripping can be caused by the drainage tube becoming
unattached from the plastic tray on the compressor.

Interior dripping can be caused by blockage of the entry point of the
pipe. Removal of any debris and a poke with a bit of [[Iron wire|
wire]] should clear this. If it blocks repeatedly, mould growth is the
usual culprit. This can usually be stopped by cleaning the interior
spotlessly.

Exterior dripping can also be caused by saturated [[insulation]].
Replacing the insulation is the only cure, which isn't worthwhile
unless the appliance is of high value. Insulation saturation usually
occurs at the bottom of the fridge.


===Smells===
Smelly fridges are usually sorted out with a thorough clean. Do not
use bleach or any scented cleaner.

If the fridge is in such a state that stinking oozes have gotten into
the [[insulation]], nothing but a new fridge will remedy this. For a
valuable fridge, replacement of the insulation is the solution.

===Thermostat===
A thermostat stuck off will make the fridge play dead. If stuck on,
the compressor will run all the time, consuming excessive energy.

Thermostats can be DIY replaced, but its not worth it for the average
fridge. The capillary tube on the stat usually passes through the
fridge's [[insulation]], and the whole assembly must go in without
being cut. The old one can be cut if necessary, as it doesn't need to
work again. Generic replacement stats are available.

===Compressor runs but not cold===
This is caused by loss of refrigerant, which is caused by a leak. A
gas refill will only leak out again.

===Compressor dead===
Compressors can be replaced, but again most fridges aren't worth it.

===Partial short===
A compressor with a partial short will overheat very quickly and cut
out. Or it may blow [[fuse]]s. Its posible to make these run by adding
a high power series resistance to limit the short current, but the
increased energy consumption and low cost of replacement fridges makes
it not usually worthwhile. A 240v 3kW heater makes a suitable series
resistance.

===Noise===
Fridge noise is usually caused by something touching the compressor or
failure of the rubber suspension under the compressor. The latter can
be fixed by inserting chunks of rubber under the compressor, making
sure it can still move slightly.

===Refrigerant loss===
When a gas leak occurs, repairers may offer to refill. However if it
leaked out once, it will do so again, so this will only ever be a
temporary repair. Locating a very slow leak to fix it is extremely
difficult.

The situation is different with belt driven in-car compressors. These
leak refrigerant as a normal part of operation, and eventually require
refill.

===Seal damage===
Door seals can be replaced. Peel the seal back to locate the screws.


==Cleaning==
Be sure to avoid all scented cleaners. Avoid [[Scraper|scourers]]
which will make the interior lining harder to clean in future. Avoid
bleach too. Cream cleaner and a cloth are normally effective, with a
brush for any residue buildup. Stubborn dirt should be soaked to
loosen.


==Storage==
Unused fridges should be stored with door ajar to avoid bad odours.
When the door may get closed, placing a couple of clean dry teabags
inside will help.


==Cooling arrangements==
There are 3 common cooling arrangements:
# Heat exchanger at back. Requires rear ventilation, but no side
ventilation.
# No external heat exchanger. These have cooling tubes built in under
the outer skin, and require side ventilation for cooling.
# Less common is cooling underneath the fridge, with warm air expelled
at the front at the base. Such fridges require no ventilation to sides
or rear.


==Side gap==
Its traditional to leave a small gap each side of a fridge. This gap
makes moving the appliance easier, avoids the door catching, avoids
vibration noise and increases rear ventilation. Newer fridges with no
external heat exchanger need side ventilation for cooling.


==Wire vs glass shelves==
Glass shelves are wipe cleanable, and minimise spills of meat juices
etc onto foods below.
Glass and wire are both dishwashable.

Glass shelves can't always be retrofitted into a wire shelved fridge.
Glass blocks air circulation, and this can sometimes result in
inadequate cooling in fridges designed for wire. If retrofitting
you'll need to check the temp on each shelf afterwards.


==Energy efficiency==
The energy efficiency of fridges has improved substantially since the
1970s. A free 70s fridge will generally cost more in total over its
lifetime than a new one.


==Refrigerants==
Until recently nearly all fridges used the CFC R12, also known as
freon. New fridges use any of several HC and HFC refrigerants. Some of
these are believed to affect the ozone layer as well, some not.

===Propane===
Fridges in third world countries normally use propane (or similar
gases) as the refrigerant. These gases are cheap and efficient, but
leaks are potentially explosive. Despite this, data indicates that
real world risk is negligible. A very few fridges here also use such
gases, and with these one should ventilate well if gas is smelt.

Propane is also sometimes used by DIYers to repair fridges and a/c
systems that were designed for R12, R-22 or R-134a. Its cheap, readily
available, a plug-in replacement, and 9-15% more energy efficient than
R12, but its also highly flammable.

Propane refrigerant is labelled as R-290. Note that bottled propane is
a propane butane mix, not pure propane.

Butane is R-600 and works at low enough pressure to be contained in
reinforced plastic hose.

Pentane is another low working pressure refrigerant gas.



I have a bosch fridge 4.5 years old and it runs on Butane / Propane...

===Ammonia===
Ammonia has long been used in a small percentage of fridges using the
ammonia absorption cycle. These fridges are almost totally silent,
with just the thermostat's click and the occasional quiet gurgle. They
are easily spotted:
* the equipment on the rear looks quite different to compressor
fridges
* They are completely silent when first plugged in

There are 2 issues with these fridges.
# Power consumption is relatively high, due to low thermal efficiency
# Even a mini fridge contains over 1kg of ammonia, which would be
fatal if released.

The advantage of these fridges is they can in principle be run off any
source of heat, such as 240v, 12v or bottled gas. Hence they are
standard equipment in caravans.


==Antique fridges==
===R12===
Safe R12 refrigerant was introduced in the mid 1930s. Old fridges
using R12 and a sealed compressor unit will behave much like modern
fridges, albeit with relatively poor energy efficiency, and without
all the other modern refinements such as wipe clean linings, safe door
latches, even temperature, low noise level and so on.

===Belt drive===
Earlier fridges used a separate motor and belt driven compressor.
These are less efficient, and the compressor gradually leaks
refrigerant, so needs refilling in time. The belt can slip or break.

Some belt driven fridges didn't use R-12, and are a safety problem -
see below.

===Pre- R-12 fridges===
These all used a belt driven compressor, along with assorted nasty
refrigerants. Belt diven compressors leak gas as a normal part of
operation. The refrigerants used vary from toxic to very toxic, and
some are explosively flammable. Such fridges are not suitable for use
in inhabited spaces, and never were.

Refilling with modern refrigerants is problematic, as the working
pressures of these old systems are often too far removed from those of
modern equipment to produce a workable refrigeration cycle. Some of
the old refrigerants (eg SO2) are sufficiently safe to use if the
location is well ventilated and isolated from the main building. Some
are absolutely not.

Butane and pentane work with lower pressures than R12, and may be
usable in some cases. Ventilation is necessary when using a highly
flammable gas in a belt drive compressor.


==Peltiers==
New mini fridges usually use peltier heat pumps instead of the ammonia
absorption cycle. Like ammonia, these are silent and have poor energy
efficiency, but the very remote risk of ammonia release is not there.

These fridges don't generally have the same cooling power as standard
fridges, with the ability to only cool by upto 15°C being normal. Thus
they are not safe to use as a main fridge from a food poisoning point
of view, as food stored at 15°C in a hot 30°C room will spoil rapidly.
This is why they are usually described as drink chillers only. If
wanted to store food, the interior temp should be monitored and the
machine only used for foods requiring refrigeration when sufficiently
cool. Foods that don't require refrigeration (such as chocolate) are
safe to store in them.

The peltier pumps used in these are usually rated at 12v 5A, but can
run on anything upto 16v for maximum cooling. Some of these mini
fridges also have a fan or a second peltier, doubling power use.


==Temperatures==
5°C is the recommended fridge temp for food storage.

Temperatures in fridges tend to vary from one location to another. The
salad crisper operates at high RH and slightly higher temp, keeping
salads firm for longer and avoiding any risk of freeze damage.
Enclosed spaces mounted on the door also run at slightly higher temp,
and are good for keeping butter, making it not quite so hard.

Areas close to the cooling plate run colder, and foods such as salads
can be damaged by frost if put there.


==TCO==
Annual Total Cost of Ownership depends on purchase cost, life
expectancy and energy cost. Hence the most energy efficient models
aren't necessarily the best value ones, but are more likely to be if
all other factors are equal. Naturally all other factors aren't equal
in practice, since maximising energy efficiency costs money.

Life expectancy is an important factor when seeking to minimise TCO.

Having said all this, there is no single simple strategy to minimise
TCO, and no hard reliability or life expectancy data to base
calculations on. News:uk.d-i-y and expert websites sometimes discuss
TCO reduction strategies, but opinion remains divided.



==Food safety==
# Check the fridge temperature is correct.
# Inspect contents regularly, removing anything that is beginning to
spoil.
# Avoid arranging foods so that meat juices could drip onto other food
types.
# Keep the fridge interior clean.
# Glass shelves reduce cross contamination by reducing drips.



==Disposal==
Local councils usually take fridges and freezers away free. Local
dealers will purchase or collect the very few types of fridge they
could repair and sell profitably, but this only applies to high ticket
items.

Most other disposal options are now illegal for R12 fridges, since it
is no longer permitted to release R12 to the atmosphere.

===Compressors===
Compressors removed from fridges have their uses. They provide
compressed air at high pressure but low flow rate, and require an oil
catcher if they're to last.


==The dial==
Fridge dials are usually marked with numbers unrelated to actual
temperature. The only way to determine temperature is to leave a
thermometer in the fridge.

A few fridges also have an [[insulation]] sheet between icebox and the
main fridge space. The position of this can be adjusted in conjunction
with the thermostat dial to achieve the desired temperatures in both
fridge and icebox sections. The sheet is moved to adjust the relative
temps of fridge and icebox; when blocking all airflow there will be
maximum temp difference, and when opened there will be less temp
difference.


==Improving energy efficiency==
For most of us the simple way to improve energy efficiency is to
replace the 1980s fridge with a modern A rated one.

===Energy saver plugs===
Energy saver plugs reduce energy consumption in older fridges, but are
incompatible with a lot of new fridges, some of which have this
technology built in.

Energy saver plugs pass full power to the compressor during starting,
then throttle the power back once running.

In many places a 10 year old fridge can be bought for the price of one
of these plugs, and will deliver more performance improvement, so even
for older fridges their use isn't very popular.

===More aggressive methods===
People running fridges on small solar electric systems sometimes wish
to reduce energy consumption. Any of the folowing can help:
* Add more polystyrene [[insulation]] on the outside of the fridge
(watch for condensation on the metal cabinet, which can rust it)
* Use an energy saver plug when compatible
* Put frozen items in the fridge overnight when defrosting them
* Write contents on a wipe clean board on the front, then decisions
can be made with the door closed.


==See Also==
* [[Special:Allpages|Wiki Contents]]
* [[Special:Categories|Wiki Subject Categories]]
* [http://www.wou.edu/~avorder/Refrigeration.htm Refrigerant history]



[[Category:Appliances]]
[[Category:Cooling]]
[[Category:Fault Finding]]
[[Category:Energy Efficiency]]
[[Category:Cleaning]]
[[Category:Kitchens]]
[[Category:Repair]]

"James Salisbury" nntp.dsl.pipex.com wrote in message
...
wrote:
Pentane is another low working pressure refrigerant gas.

I have a bosch fridge 4.5 years old and it runs on Butane / Propane...

Is there a wiki on snipping?

James Salisbury wrote:

I have a bosch fridge 4.5 years old and it runs on Butane / Propane...


Ours ran on natural ...

Don't seem to be able to buy domestic gas fridges now except for the
mobile variety.

--
Adrian C

On Aug 4, 2:17*am, wrote:
Another article to pore over before it goes up....

NT

Most people now have a fridge freezer as their main machine, but
fridges are still useful for supplemental space.


OK, most of what you've suggested has been incorporated, with thanks.
I'll explain below why some things havent been as yet.


Too high a temp at the rear causes overheating of compressor, with
consequently much reduced life.

I'm not aware of any evidence for this statement. At higher
temperatures, the cooling effect reduces, eventually to nothing,
and this reduces the power output at the rear, so it's a somewhat
self-regulating effect on rear temperature. The significant factor
is that the fridge operating efficiency plummits, and interior will
get too warm in bad cases.

The compressor is cooled mainly by the refrigerant. The heat in the
compressor's refrigerant gas output needs to be lost in the external
heat exchanger. If this doesnt happen, the coolant circuit is running
continuously with much higher freon temps in and out, leaving the
compressor running much hotter. It still works, but the windings wont
last as long.


Re series resistors to run a partial short:

I don't believe this would work.

I used to do it


Fridge compressors have barely enough
power to start (they will fail to start sometimes - this is expected).
With a series resistance, the chance of starting failure is going to
be very much higher.

thats right, so sometimes it just cycles until it starts. A stalled
attempt to start leads to the overheat cutout opening, when it closes
it tries again. This is why 2-3kW is used rather than less.


A compressor with a shorted turn has had it. Period.
It will run, but it will be drawing some kW's rather than 100W,
and will quickly trip its overcurrent circuit.

True with no series R, but with one the heat is dissipated mostly in
the heater when it hits the partial short each time it goes round, so
the motor keeps going. It does work.

The heater limits the current drawn during the shorted section, and
most of the time its drawing normal i, so theres no kilowatt
consumption.

These tricks see use in industrial settings where losing equipment and
all the food stored in it plus the business opportunity afforded by
the equipment would be an expensive loss. Equipment is kept running
temporarily until a new compressor is installed.


No pre-preprepared cleaners should be used.

I've cleaned many fridges, and never had a problem with unscented
commercial cleaning chemicals. Bicarb OTOH I've found pretty
ineffective. Lots of sites say use it, but you can buy far better at
any supermarket.


Fridge interior design allows for the shelf types. You can't change
them restrospectively.

I'm not aware of anything to stop anyone. In some cases if you have
some glass shelves from a dead machine they will slot in and work
fine. And sometimes not.


Ammonia is also used as a refrigerant gas in giant (warehouse sized)
freezers (and maybe fridges).

yes, as are various other gases, vortex tubes and so on. Industrial
refrigeration equipment doesn't strike me as very DIY, but you could
write an article on it if you like.


chrisj:

I'm surprised you say it's not worth replacing. Under a tenner for a
generic one on eBay is a lot cheaper than a new fridge at several
hundred. But modern fridges with LED displays presumably use more
sophisticated thermostats which are not DIY-replaceable?

A standard used fridge is only £20-30. Some of course will be worth
doing, but most not.


You might add that a temporary workaround for a thermostat stuck on
(or a bridged one stuck off) is to run the fridge off a timeswitch
programmed for (say) off 15mins of every hour.

Considering the real and serious risks of food poisoning I dont think
its something I or we could recommend in good faith. Better to let it
run continuously if you must bodge it.


NT

Andrew Gabriel wrote:
Too high a temp at the rear causes overheating of compressor, with
consequently much reduced life.

I'm not aware of any evidence for this statement. At higher
temperatures, the cooling effect reduces, eventually to nothing,
and this reduces the power output at the rear, so it's a somewhat
self-regulating effect on rear temperature.

This is not true really, the cooling effect drops off but the power
consumption doesn't fall that much.

Bit like dimming a halogen bulb, less light but still lots of heat.

If the refrigerant gets far too hot it will acidify and kill the
compresser quite quickly.

The solution is more ventilation. Where its problematic to provide
this, a quiet 3" or 4" fan can be used to move air upwards behind the
machine.

Introducing forced air paths significantly increases the rate of
dust collection, and this can more than counter the forced cooling
after a while.

Not IME.

cheers,
Pete.

In article ,
Pete C ukdiy writes:
Andrew Gabriel wrote:
Too high a temp at the rear causes overheating of compressor, with
consequently much reduced life.

I'm not aware of any evidence for this statement. At higher
temperatures, the cooling effect reduces, eventually to nothing,
and this reduces the power output at the rear, so it's a somewhat
self-regulating effect on rear temperature.

This is not true really, the cooling effect drops off but the power
consumption doesn't fall that much.

Power consumption only accounts for 25-33% of the heat output.
When it's hot enough that the cooling effect has ceased, power
output at the back is therefore reduced to 25-33% of normal.
That's the self-regulating effect as temperature rises.

Bit like dimming a halogen bulb, less light but still lots of heat.

If the refrigerant gets far too hot it will acidify and kill the
compresser quite quickly.

The solution is more ventilation. Where its problematic to provide
this, a quiet 3" or 4" fan can be used to move air upwards behind the
machine.

Introducing forced air paths significantly increases the rate of
dust collection, and this can more than counter the forced cooling
after a while.

Not IME.

Sorry, but this is a well-known effect in the design of equipment
cooling.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Andrew Gabriel wrote:
Power consumption only accounts for 25-33% of the heat output.
When it's hot enough that the cooling effect has ceased, power
output at the back is therefore reduced to 25-33% of normal.
That's the self-regulating effect as temperature rises.

You're forgetting something pretty basic.

The hotter it gets the more *additional* heat leaks back into the
fridge!

So the cooling effect will *never* cease, the cooling demand goes *up*
and the efficiency of the compressor goes *down*.

The duty cycle of the compressor will go to 100%, increasing it's
temperature by the maximum in an already hot ambient temperature.

Running a compressor for longer at much higher temperatures *will*
shorten it's lifespan!

I do hope I have made things clear enough

cheers,
Pete.

In article ,
Pete C ukdiy writes:
Andrew Gabriel wrote:
Power consumption only accounts for 25-33% of the heat output.
When it's hot enough that the cooling effect has ceased, power
output at the back is therefore reduced to 25-33% of normal.
That's the self-regulating effect as temperature rises.

You're forgetting something pretty basic.

The hotter it gets the more *additional* heat leaks back into the
fridge!

That's the same heat going round, not additional heat.
Additional heat can only come from heat leaking into the
fridge from elsewhere in the room. When the fridge gets
to room temperature inside, that can't happen. The only
heat output from the back at this point is down to just
the energy drawn by the compressor.

Of course, if you really blanket the thing with thermal
insulation, then just the heat from the compressor will
eventually kill it, but a wooden cupboard won't manage
that, just inefficient operation and failing to keep
down to temperature inside. Seen this done many times
by kitchen fitters with a poor grasp of physics.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Andrew Gabriel wrote:

The hotter it gets the more *additional* heat leaks back into the
fridge!

That's the same heat going round, not additional heat.
Additional heat can only come from heat leaking into the
fridge from elsewhere in the room.

No!!!

Heat *also* leaks directly back in from behind the fridge where the
compressor and condenser is!

That's what I mean by additional heat.

cheers,
Pete.

In article ,
Pete C ukdiy writes:
Andrew Gabriel wrote:

The hotter it gets the more *additional* heat leaks back into the
fridge!

That's the same heat going round, not additional heat.
Additional heat can only come from heat leaking into the
fridge from elsewhere in the room.

No!!!

Heat *also* leaks directly back in from behind the fridge where the
compressor and condenser is!

That's what I mean by additional heat.

It's not additional - it came from the compressor,
i.e. it's part of the compressor's power consumption.
At this point, if the compressor is consuming, say, 80W,
there's still only 80W coming out the back rather than
the ~300W you'd get when the fridge is operating normally.
There's nowhere else for power to come from once energy
leakage into the fridge from the room stops due to no
temperature differential.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Andrew Gabriel wrote:
It's not additional - it came from the compressor,
i.e. it's part of the compressor's power consumption.
At this point, if the compressor is consuming, say, 80W,
there's still only 80W coming out the back rather than
the ~300W you'd get when the fridge is operating normally.
There's nowhere else for power to come from once energy
leakage into the fridge from the room stops due to no
temperature differential.

I think you'd have a duff compressor before reaching that point

cheers,
Pete.