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    Types of compressors rotary vs recip - OLD fridges (1 Post)

  • ChrisJ ChrisJ @ 10:59 AM
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    Types of compressors rotary vs recip - OLD fridges

    I'm curious what the advantages and disadvantages of reciprocating and rotary compressors are?

    As many know, I have been restoring two 1930s refrigerators for a while now and I've studied everything I can find on them.

    One thing that had me wondering for a bit was why GE switched from SO2 to methyl formate for 2 years and then back to SO2. From what I've found it was due to non-condensibles causing problems due to moisture breaking the refrigerant down. This lead to service calls where repairmen would "bleed" the system and let the non-condensibles out without letting much if any refrigerant out. Either way it lead to angry customers.

    What I don't understand is why GE used reciprocating compressors with SO2 but used a rotary design with the methyl formate.

    I'm hoping someone may have an idea why? What I can tell you is SO2 is similar to R12 as far as operating pressures where methyl formate operates under a substantial vacuum on the evaporator side. My guess has been a rotary is better at low pressure operation but I have no clue honestly. Both use what appear to be called flooded evaporators where refrigerant flow is regulated with a highside float.

    I have a 1933 and 1934 unit which are both methyl formate \rotary units and all I can say is I have never heard such a beautiful sounding pump anywhere else.

    On a side note, both reciprocating and rotary compressors used on these have a unloader than holds the intake valve open until oil pressure reaches a certain point. This actually allows the pump to start with a high head pressure and I have personally tested it by unplugging the fridge for a second, allowing it to stop and plugging it back in. It started right up.
    Weil-McLain EG-45 connected to 392sqft of radiation via two 2" risers into a 3" drop header and 2" equalizer. Using Rectorseal Steamaster water treatment to greatly reduce corrosion in the boiler.

    Boiler pictures.
    This post was edited by an admin on May 7, 2013 11:04 AM.
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