Another article to pore over before it goes up....
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
Larders contain no icebox, and don't frost up, so are frost free.
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.
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.
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
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
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.
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.
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.
Compressors can be replaced, but again most fridges aren't worth it.
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
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.
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
The situation is different with belt driven in-car compressors. These
leak refrigerant as a normal part of operation, and eventually require
Door seals can be replaced. Peel the seal back to locate the screws.
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
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.
There are 3 common cooling arrangements:
# Heat exchanger at back. Requires rear ventilation, but no side
# 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
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.
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.
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.
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 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
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.
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.
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 -
===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.
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.
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.
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.
# Check the fridge temperature is correct.
# Inspect contents regularly, removing anything that is beginning to
# Avoid arranging foods so that meat juices could drip onto other food
# Keep the fridge interior clean.
# Glass shelves reduce cross contamination by reducing drips.
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
Most other disposal options are now illegal for R12 fridges, since it
is no longer permitted to release R12 to the atmosphere.
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.
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
==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.
* [[Special:Allpages|Wiki Contents]]
[[Special:Categories|Wiki Subject Categories]]
* [http://www.wou.edu/~avorder/Refrigeration.htm Refrigerant history]