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libspero

Fridge Puzzle

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Ok,

Engineering / physics puzzle for the forum..

In my life I've had two fridges that have eventually died, each with the same symptoms, so I assume this is the typical way a fridge "dies".

After the obligatory national minute's silence I got to wondering about the symptoms.

Invariably what you get is a large block of ice over the elements / back of fridge and then a temperature rise in the rest of the fridge making everything else only slightly under room temperature.

You would think the big block of ice would keep everything cold, but it doesn't. Obviously turning up the power doesn't help either.. you just get a bigger block of ice.

The only reason I can think of is if the insulation failed, the fridge would warm up and the element go into overdrive.. but can insulation really "fail"? the door seals usually look ok and there's not much else to go wrong with insulation surely?

Has anyone else ever noticed this and actually managed to figure out what is going on?

Your anxiously,

Libs

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Do you know how a fridge actually works?

Cold elementy bit at the back gets cold.

Once the fridge reaches the right temperature the thermostat turns the cold elementy bit off so it doesn't frost/get too cold.

When the temperature rises it turns the compressor back on again and makes the cold elementy bit cold again.

Except in an old broken fridge. Apparently.

Close?

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Cold elementy bit at the back gets cold.

Once the fridge reaches the right temperature the thermostat turns the cold elementy bit off so it doesn't frost/get too cold.

When the temperature rises it turns the compressor back on again and makes the cold elementy bit cold again.

Except in an old broken fridge. Apparently.

Close?

That's better than my a level physics teacher ever managed

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Door seals knackered /door warped ..the refrigeration part is working hence the ice the ice builds up because there a continuous supply of air due to the seals leaking

Easy test is when you open the door there should be resistance due to the vacum created when the warm air contracted when it cooled down if you don`t have this the door seal is knackered

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Wot LTL said

The contents of the fridge being near ambient, even though they're sitting next to a block of ice, being a bit of a clue.

Top fridge tip, clean the coils at the back of the fridge every year or so. It will be grateful.

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So it's a thermostat fail?

I'd go with that if it wasn't that the rest of the fridge is warm. If it was just permanently running I'd expect everything to be super cold (I think)

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Door seals knackered /door warped ..the refrigeration part is working hence the ice the ice builds up because there a continuous supply of air due to the seals leaking

Easy test is when you open the door there should be resistance due to the vacum created when the warm air contracted when it cooled down if you don`t have this the door seal is knackered

That was my first thought but the door seals seem pretty ok (visually).. hence I was wondering about insulation more generally. But perhaps it really is as simple as that.

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Do you know how a fridge actually works?

It makes "cold" from electricity! :blink:

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That was my first thought but the door seals seem pretty ok (visually).. hence I was wondering about insulation more generally. But perhaps it really is as simple as that.

It probably is.

An alternative is that your fridge is so rammed there's no air circulation. Though the ice build up suggests there's warmy wet air getting in there and condensing on the coldy element bit.

OCD poltergeist with a fridge door opening/closing fixation?

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We bought a Leibherr fridge freezer 2 years ago. The frost free freezer keeps getting thick with ice at the back and the freezer food feels soft. Does that sound like the seal or the thermostat? I don't understand these things.

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That was my first thought but the door seals seem pretty ok (visually).. hence I was wondering about insulation more generally. But perhaps it really is as simple as that.

Worn hinges can also cause the problem as most fridges just have simple pin and bush hinges the bush wears and become oval over time

Insulation is usually rockwool/glass fiber in older fridges and eps/xps polystyrene in newer ones cant see how any off this can fail

If theres no vacuum created you have a air leak and odds on it`s the door not sealing

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So no. :lol:

How Refrigeration Works


To grasp the energy implications of refrigeration systems it helps to have a clear understanding of how these systems work — how they go about creating temperatures low enough to cool and freeze. Fortunately, the basics are fairly straightforward.

The diagram at the right illustrates a typical mechanical vapour-compression refrigeration system. Such systems include several key pieces of hardware:

· a compressor,

· a condenser,

· an expansion or throttling device such as the TX valve shown, and

· an evaporator.

There is also, of course, a refrigerant fluid that flows in a closed path around the system.

We know that water, propane, and other fluids are sometimes in a vapour or gas state and sometimes in a liquid state, depending on the temperature and pressure to which they are subjected. In this respect, refrigerants are no different. It’s just that refrigerant fluids change from liquid to gas at temperatures and pressures suited to refrigeration purposes. Refrigerants, for instance, “boil” at a much lower temperature than water.

Refrigeration depends on changes of pressure, and two of the devices mentioned above create these changes. The compressor raises refrigerant pressure; the TX valve (or similar device) lowers it. In fact, it is convenient to divide a refrigeration system into two pressure zones or domains: a high pressure zone, and a low pressure one.

Knowing this, try again.

Source : http://www.wisdompage.com/SEUhtmDOCS/3SE5.htm

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We bought a Leibherr fridge freezer 2 years ago. The frost free freezer keeps getting thick with ice at the back and the freezer food feels soft. Does that sound like the seal or the thermostat? I don't understand these things.

That sounds like exactly the same thing as mine.. but with a freezer instead of a fridge.

Wouldn't expect it on a new fridge though :unsure:

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That sounds like exactly the same thing as mine.. but with a freezer instead of a fridge.

Wouldn't expect it on a new fridge though :unsure:

I've sent two, admittedly not very expensive, fridges straight back to a leading high street chain this last year on account of them not sealing properly.

And I'm not a chap who's in the habit of sending stuff back.

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Worn hinges can also cause the problem as most fridges just have simple pin and bush hinges the bush wears and become oval over time

Insulation is usually rockwool/glass fiber in older fridges and eps/xps polystyrene in newer ones cant see how any off this can fail

If theres no vacuum created you have a air leak and odds on it`s the door not sealing

I'm not sure if I have a vacuum or a sticky door.. there's certainly a bit of resistance when you open it.

I'll examine the door seals and try defrosting it over night and see if that magically cures it. Sounds like the door seals are most likely.

To be fair it's one of these:

guinness-kule-kube-refrigerator-xl.jpg

..and about 12 years old!

We've been using it as an overflow fridge for the past year or so when we've filled up the main one.

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We bought a Leibherr fridge freezer 2 years ago. The frost free freezer keeps getting thick with ice at the back and the freezer food feels soft. Does that sound like the seal or the thermostat? I don't understand these things.

Could be a door sealing issue but frost free have a few more systems to go wrong that could be causing the problem, here's is a good explanation of these systems http://home.howstuffworks.com/question144.htm

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I'm not sure if I have a vacuum or a sticky door.. there's certainly a bit of resistance when you open it.

I'll examine the door seals and try defrosting it over night and see if that magically cures it. Sounds like the door seals are most likely.

To be fair it's one of these:

guinness-kule-kube-refrigerator-xl.jpg

..and about 12 years old!

We've been using it as an overflow fridge for the past year or so when we've filled up the main one.

Got one similar ,i would start on the hinges if the seals look ok as IIRC they are adjustable via the screws that fasten the plates that the pins are on ,to the fridge body top and bottom also check for play between the pins and the bushes and adjust it out if possible

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Guest eight

Do you know how a fridge actually works?

Of course - I've seen The Mosquito Coast.

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I'm not sure if I have a vacuum or a sticky door.. there's certainly a bit of resistance when you open it.

The seals are magnetic. Even if there's no vacuum, there'll be a feeling of resistance.

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Ok,

Engineering / physics puzzle for the forum..

In my life I've had two fridges that have eventually died, each with the same symptoms, so I assume this is the typical way a fridge "dies".

After the obligatory national minute's silence I got to wondering about the symptoms.

Invariably what you get is a large block of ice over the elements / back of fridge and then a temperature rise in the rest of the fridge making everything else only slightly under room temperature.

You would think the big block of ice would keep everything cold, but it doesn't. Obviously turning up the power doesn't help either.. you just get a bigger block of ice.

The only reason I can think of is if the insulation failed, the fridge would warm up and the element go into overdrive.. but can insulation really "fail"? the door seals usually look ok and there's not much else to go wrong with insulation surely?

Has anyone else ever noticed this and actually managed to figure out what is going on?

Your anxiously,

Libs

Last problem I had with a fridge like this, I had to buy a heater for it.

Big block of ice, clearly its too cold. Get a heater for the bit that makes it cold. It wraps around that bit, stops it geting too cold.

Seriously.

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Of course - I've seen The Mosquito Coast.

That has a great line when the guy tells River Phoenix his dad is the most dangerous sort of man, a know-it-all who's occasionally right.

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