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Scroll Compressors

Servicewiz_3
Servicewiz_3 Member Posts: 58
in A-C, Heat Pumps & Refrigeration

Can scroll compressors experience locked rotor amps? If so , can a hard

start be used?

mattmia2

Comments

  • ChrisJ
    ChrisJ Member Posts: 16,315

    They do for a short burst during startup.

    To my knowledge they do have unloaders and 2 stage ones start in low stage which helps.

    If you look up a Copeland scroll you'll see a hard start specified for that specific compressor.

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • Big Ed_4
    Big Ed_4 Member Posts: 3,019

    You can try to kick start , but with odds its done …

    There was an error rendering this rich post.

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,470

    If your try one I would use what the MFG recommends rather than the generic ones the supply house sells. Sometimes needed if your voltage is a little low.

    Check your breaker and supply wiring and make sure the wire is not undersized and that all connections are clean and tight.

    Other than that the compressor may have mechanical damage or

    too much oil in the compressor from repeated compressor changes or

    no crankcase heater or

    flood back or to much refrigerant in the system or

    a defective metering devise

  • mattmia2
    mattmia2 Member Posts: 10,924
    edited April 30

    lra has to do with the motor starting from a standstill, has nothing to do with the load connected to it. It is how you size the conductors so that there is not too much volatage drop and how you size alternate power sources.

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,470

    @mattmia2 true. but if the compressor is locked up with oil or refrigerant due to a bad CC heater or something else I mentioned above it could draw LR

  • ChrisJ
    ChrisJ Member Posts: 16,315
    edited April 30
    https://forum.heatinghelp.com/discussion/comment/1800652#Comment_1800652

    Do scrolls actually get locked up from oil?

    I thought they originally claimed you didn't even need a CC heater on scrolls, but later changed to recommending them because the refrigerant was "watering down" the oil too much causing excessive wear on startup? I'm trying to remember back almost 10 years now, so, that could be way off.

    I thought the housing on a scroll was the discharge side?

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • pecmsg
    pecmsg Member Posts: 5,290

    the housing is all suction.

    ChrisJ
  • ratio
    ratio Member Posts: 3,788

    They'll happily pump shaving cream, which is why they put the CCHs back on.

    Nobody's mentioned it, but you only need a hard start kit with a single-phase motor.

    ChrisJ
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,470

    Yeah, when scrolls first came out they said "you don't need crankcase heater scrolls can pump liquid" Carrier was a big offender on this they didn't use CC heater when scrolls first came out"

    We have all seen how that worked out. It didn't.

    Scrolls can bust up just as easy as a recip. Compressors are made to pump gas. If you feed them too much liquid or oil they will bust up.

    The reason I mentioned oil is every replacement compressor comes with a full oil charge. When you do a replacement how do you know how much oil is left in the system? You don't.

    Some recommend measuring the oil in the old compressor and if there are no oil leaks in the system you remove some oil from the new compressor so that it matches the old compressor oil charge.

    My point was and is if a bad system gets multiple compressor replacements you can end up with too much oil in the system.

    ChrisJPC7060SuperTech

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