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  1. #1
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    inverter systems



    hi guys,
    i was just wondering.that for normal air conditioners in Australia i normally look at the suction pressure R22 to be 60 psi or 1 to 4 degrees pressure temp. and high side 250 psi , and takes the temp of the day into account. i am pretty sure this the right way to check pressures provided indoor fan and condenser fan is running filters are clean. amps are according to specifications. correct me on this one if wrong. on the other side these new inverter system where compressor can actually fluctuate the speed.i mean can work harder and softer in order to achieve the set point. how does it effects the pressure . will the pressure be different from a normal old style units? haven't had a chance to hook gauges on to the running operating unit.
    thanks



  2. #2
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    Re: inverter systems

    .

    It's not just the compressor.

    To achieve the cooling effect (or heating) the evap runs
    at a set loading, the evap fan runs at a set speed.

    If the loading in the room changes, the loading over the evap changes and
    the evap fan winds up to increase air flow (the metering device may open as well).

    As the evap does more duty (or less) it will effect the loading's on the comp so the comp
    ramps up or down to cater for the new load. As the compressor ramps up or down
    this now puts extra or less load on the condenser so the cond fan speeds up or slows
    down accordingly.

    Rob

    .
    Last edited by Rob White; 23-04-2013 at 12:43 PM.
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  3. #3
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    Re: inverter systems

    The best values to check for when you got your gauges connected is the subcooling or superheat. (search this forum for more information about what this is and how to measure it).

    Without gauges on a single split system the temperature difference of the air across the indoor coil is quite reliable as long as you got a baseline to compare with (normal delta T at low/medium/high fanspeed)

    However, you are right, an inverter will affect all those measurements. The only surefire way of doing it on an inverter driven system is to put it in to TEST mode, check that the compressor is fully ramped up (most decent clamp AMP meters will give frequency as well) and then take your pressure/temp readings.



    .

  4. #4
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    Re: inverter systems

    hi viking and rob
    do you mean when you put unit onto test mode using a button on the thermostat, unit will assume it self being under full load and will give the best reading as like other normal old style air-conditioners ??
    thanks

  5. #5
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    Re: inverter systems

    .

    Yes.

    Test mode will manually set the compressor speed.

    Rob

    .
    .. ... -. .----. - / -- --- .-. ... . / -.-. --- -.. . / --. --- --- -..

  6. #6
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    Re: inverter systems

    thanks buddy

  7. #7
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    Re: inverter systems

    Yes...

    There is just one thing to be aware of, some manufacturers have designed their units to stay within certain temp/pressure crirerias even when the system is in test mode, hence the check to confirm the compressor is fully ramped up.


  8. #8
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    Re: inverter systems

    120 PSI thereabouts on suction line when it's ramped up. Gas side is the least of your dramas, wait till the damned thing is exposed to electrical surges, communications problems, wild life....
    To the optimist, the glass is half full. To the pessimist, the glass is half empty.

  9. #9
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    Re: inverter systems

    test mode overrides the thermostat control only for 20 mins on a daikin or 2 hrs on a mitsi, compressor speed will still vary dependant on room temp,and safe operating limits(discharge pressure control, pipe temps
    Quote Originally Posted by Rob White View Post
    .

    Yes.

    Test mode will manually set the compressor speed.

    Rob

    .

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