What is a compressor?

Discussion in 'Shop Talk' started by bridget, Jun 23, 2005.

  1. bridget

    bridget Well-Known Member

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    My window unit ac is going out and the maintenance guy said I need a new one. The unit is shuddering and than makes a loud thump. Really loud. Won't cost me anything since I'm in an apt., but I realized I haven't a clue what a compressor is or does. Also, is it better to leave the air exchanger open or closed? Thanks
     
  2. fordy

    fordy Well-Known Member

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    ...............Bridget , They sell small window unit type units at , W.Mt. , Home depot and Lowes . You'll probably need a 10,000 to 12,000 btu size for your apartment . The higher the BTU number the more cold air it can produce therefore the Larger area inside it will keep cool . Better to have alittle extra than not enough BTU's . They will also show the EER ratio on the outside of the Box ...EER = energy efficiency ratio . Most units in the 8,000 to 12,000 btu range will have an EER around 9.5 . Max is a 15 I believe . The higher the EEU the more efficient the unit "is" in producing a given amount of cold air . Just about anyone can install one of these units if they use alittle common sense . Take a male friend to a couple of the above stores and "price" some of the available units . Be sure you are comparing Equivalent BTU ratings when you comparison shop at several different stores . Prices will range from 200 to 450 or so , SO become a Knowledgeable Consumer . Good luck , fordy.. :)
     

  3. Ozarks_1

    Ozarks_1 Well-Known Member

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    Simple explanations:
    Compressor: Think of the compressor as an air cooling and circulating pump.

    Air exchanger: Open if you want the outside air to mix with the room air (such as ventilation with the fan only on the unit). Closed if you're using the AC (to retain the cooler air in the room).
     
  4. 2story

    2story Well-Known Member

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    A compressor pumps and compresses refrigerant. the cool things is it is an electric motor in a case cooled by the incoming refrigerant.
    closed, your conditioning the air in side your apartment.
     
  5. farminghandyman

    farminghandyman Well-Known Member Supporter

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    the compressor is the working part of the AC, if the cover is off it would probly be a black looking rounded tank looing unit with a few pipes and wires coming out of it, IN side of it is an electric motor and a small piston, that moves the refergerant around in the AC unit to the evaporator coil, (the one on the inside of the house and to the condenser coil the one on the out side of the house side, the refergerant moves the heat, and the compressor moves the refergerant,

    there is another motor fan and that blows air through both coils,

    A window AC pulls in sided air in to the box and then cools it and blows it back in side,
    there is a small vent, I would keep it closed, unless you need some air exchange, for fressness of the inside air,
     
  6. Ed K

    Ed K Well-Known Member

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    Compressor as explained above.

    As far as the exchanger goes it depends on a the outside temps and humidities compared to those inside.

    If it's humid outside I'd probably leave it closed or you'll bring in a lot of humidity that the air conditioner will have to remove for you to feel comfortable.

    If your building is very well insulated and "tight" not at all drafty (which many apartments are not) you might want to leave the exchanger open to bring in enough fresh air.

    Also if you do a lot of cooking or showering that generates humidity the exchanger open could help if the outside air is dryer than inside.

    If it's hot out from an energy efficiency standpoint you're probably better off without opening the air exchanger.

    Sorry I can't answer your question simply but I hope that helps explain a few of the variables
     
  7. halo

    halo Member

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    Bridget, like every one is saying the compressor is basicly a pump that both compresses and moves the gas (refrigerant) in side a closed system in your AC. As the gas is pulled into the pump and then forced out the other side it becomes compressed. Think of this gas as a wet sponge. When you compress the sponge it can not hold much water and most of the water is squezed out. When the gas is compressed it can not hold very much heat and the heat is sort of squezed out. The gas then goes through a heat exchanger which is like the radiator in you car. The radiator gives the gas a place to loose this excess heat and this is why you feel warm air being blown out of the outside of the AC. Now the gas is very cold, but can not absorb heat because it is still compressed so it now goes through an area of the system that lets it expand again. If you let go of the sponge and let it expand it can soak up water again. The decompressed gas can soak up heat and goes through another heat exchanger that blows warm air from outside over it. The heat from this air is soaked up by the decompressed gas and comes out of the AC as cold air. Now the warm decompressed gas is pulled back into the compressor to start the cycle again. I hope this answers your compressor question.
     
  8. bridget

    bridget Well-Known Member

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    Thanks everybody :)
     
  9. fordy

    fordy Well-Known Member

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    ........... :cool: :cool:
     
  10. tyusclan

    tyusclan Well-Known Member

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    Not trying to be picky here but an air conditioner does not produce cold air. It removes heat and humidity from the room or building. The BTU rating tells you how many BTU's of heat the unit will remove per hour under optimum conditions.
     
  11. Alex

    Alex Well-Known Member

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    A refrigerant compressor will compress the hot refrigerant gas which comes from the room cooling coil and then pushes the gas thru the outdoor condensing unit. The outdoor condensing unit is simliar to a cooling coil, only it is in the outdoor air, still a small fan blows the outdoor air across it like the cooling coil -- see below -- but this unit rejects heat, from the refrigerant, to the outdoor air, and causes the refrigerant to condense from a gas to a liquid.

    So now the gas is compressed and cooled down and condensed to a warm-compressed-liquid. Next the compressed liquid enters an expansion valve, which is right before the evaporator or indoor cooling coil. When the expansion valve lets some gas into the coil then the gas expands and is cold.

    So, on one side of the cooling coil is this cold refrigerant gas, on the other side is air. A fan blowing the warm room air over the cold coil will let the air cool down, way below the room temperature. The air will enter your room about 55F -- this will keep your room cool -- the sun, lights, and people will heat it up. In the process of cooling the room and heating the refrigerant, it evaporates -- back to a gas -- that's why cooling coils are also called, evaporator coils.

    Then the compressor sucks the gas from the coil and the process starts all over, for your comfort and enjoyment.

    The refrigerant compressor is just like an air compressor or an engine: it has cylinders and is rotated by an electric motor, there is even oil in the refrigerant to lubricate the compressor -- just like your car engine has oil.

    Alex