Refrigeration 101

By: ssjwizard

COMPRESSOR

This is the absolute most important part of your system all other parts of your cooler revolve around this part!. The compressor will determine how fast the refrigerant can move how large of piping you can use, what kind of vacuum you can achieve on your low side. This is the heart and soul of the cooler if you get cheep here your only making it harder on you’re self. In our systems the compressor needs to run long cycles, carry a decent heat load, and be reasonable with power consumption. With that in mind you can use anything from a 1/12hp compressor up though making it all the way to 1hp is probably largely overkill. On average you will not need a compressor larger than 1/4hp and anything 1/6hp or better is above average. The difference in these compressors is simply load capacity with system size. Where a 1/4hp compressor with a small system can do an equal load to say a 1/12hp with twice as large of a system. This is accomplished by higher refrigerant speeds. With the weaker compressor it is designed to run a small cycle of probably about 40W of heat so the refrigerant wont need to be at its coldest and can cycle at a moderate speed, so in order to get this small compressor you need to increase the size of the tubing so that you can have more refrigerant in your cooler to compensate for its low flow rate. With your larger compressor the refrigerant is moving at high speed and the compressor still has room to keep the
low side pressure in a vacuum state, which results in a phenomenally lower boiling point. What your compressor can do is all determined by your budget and availability of parts. For most of us cheep is the goal now the way to do that is to try to find something someone is throwing out or at a garage sale. If you happen to see a refrigerator on the side of the road its got a possibility that it still works or has some silly thing wrong with it. So it is in our budgets best interest to knock it over and rip the compressor out and test it. Now you can get a refrigeration compressor for any number of devices. a short list of these are as follows:

01) full size refrigerator: compressor probably about 1/8 - 1/6hp
02) full size refrigerator freezer combo: compressor typically 1/6 - 1/3hp
03) chest freezer: compressor typically 1/4 - 1/2hp
04) full size freezer: compressor typically 1/5 - 1/3hp
05) mini fridge: compressor range 1/20 - 1/8hp
06) mini freezer: compressor range 1/10 - 1-6hp
07) dehumidifier: compressor range from 1/8 - 1/4hp
08) window ac unit: compressor range 1/6 - 3/4 hp

As you can plainly see they are common use. Now for those of us whom don’t have a job yet or just don’t have allot of spare cash finding one of these at a garage sale for $10 or on the side of the road can make or break the project. Now for those of us with a big wallet can purchase a compressor part. The compressor part starting at about 1/12hp typical can’t be found for under 75 dollars, for a compressor with a rating of 1/4hp you are looking at closer to 175 dollars. The biggest confusion is that a compressor is made for one particular refrigerant and CAN NOT be used for anything else. This is a myth it can be with a bit of care and effort. Something you will need to do is find out what refrigerant the compressor
was filled with originally, this information leads us to know what oil it contained this is very important. If the compressor was charged with anything other than R134a the first time then its 99% accurate to assume that it contained mineral oil this is no a huge deal. However if your compressor was originally filled with R134a this can be a problem as it contains ester oil. The reason this is a problem is if you wish to use any other freon to charge your system other than R134a it will need to be cleaned thoroughly to attempt to get all traces of oil out. If you were planing on using R290 or any other refrigerant that doesn’t come bottled with oil it doesn’t matter what’s in the compressor. Now if your compressor was R12 and used mineral oil and you want to move to R134a that is ok because you can purchase R134a that doesn’t contain oil for the porpoise of replacing R12/R22 systems. So as the compressor is the absolute most important part of your chillier I suggest you make sure that you have this first make sure it runs and has sufficient power for what you wish to do with it, as a small compressor requires to you to take further steps to insure it can handle the heat load.




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Table Of Contents:

I: MISSION STATEMENT

1: MATERIALS

2: CONDENSER

3: EVAPORATOR/RESERVOIR

4: COMPRESSOR

5: FINAL ASSEMBLY

6: REFRIGERANTS

7: CHARGING

8: MODS

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