View Full Version : Fridge and Freezer technical differences

19-01-2009, 10:14 PM

Although there are many posts on the Net about using (ie converting) a freezer as a fridge I have seen a few posts both here and on the Net in general with the general advice that a freezer should be used as such and not as a fridge.

However I cannot find any technical explanation as to why this might not be a good idea, only that it might shorten the life of the compressor.

Apart from the obvious fact that a freezer cools to much lower temparatures, can anybody explain what other differences there might be that could shorten the compressor life if a freezer were converted to cool at around 4C instead of the usual -17c ?

20-01-2009, 12:20 AM
Apart from cooling the freezer the refrigerant also cools the compressor.

If you are then going to run the compressor at up to 21C (-17 + +4) then the compressor is liable to be overheated. This will damage the oil and motor windings as well as reduce efficiency.

The MG Pony
20-01-2009, 07:18 PM
differance are mainly pressure differance and compressor displacment.

In a freezer you have a lower sst and thus low gas density and thus you can use a larger displacment compressor with a lower motor Hp as the suction gas is rarified.

Where as a fridge has denser suction gas thus a smaller displacment with a larger hp motor and the pressure differance is less due tot he lower pressure gradient.

you can convert a fridge to a freezer with little worry how ever you take a big (Well ok a huge) capacity hit due tot he small starting displacment and then adding rarified suction gas, your re-expansion inside the compression chamber is big! As the high Hp and small displacment work well in this order albeit no where near ideal!

But converting a freezer to a fridge you suffer more as now the much denser suction gas in conjunction to the large displacment and low Hp you over heat in fast order as the motor strugles to compres the denser gas!