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  1. #1
    Join Date
    May 2014
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    Goodman New Install Orifice Size

    Dear HVAC Forum,

    I just had a new condenser and evaporator installed, a Goodman model GSX130481BC 4 ton condenser and 4-5 ton Goodman model CHPF4860D6DB coil using R410A. The day after install, the system produced about a 14 degree F drop between the air intake and outlet vents. I thought this seemed low, so I read the manual which said that the unit was factory-charged for only 15 feet of copper line, and needed 0.6 oz of coolant for each additional foot of line, or about 15 more oz of coolant for our 40 foot line, plus whatever might be needed for the slightly over-sized evaporator coil.

    The installer did not add additional coolant during install, and I read on this forum that for systems without a TXV such as this one, that correct coolant charge is critical to proper operation, so I called him back to properly charge the system.

    He arrived on a 70 deg F day and added coolant, his only measures being the suction and liquid line pressure readings and putting his hand on the suction line to see if it was cool. Having read now more than a bit about wet and dry bulb temperatures and superheat and sub cooling and having developed at least some small appreciation of the complexities of HVAC systems, I am forced to conclude that my installer is either unable or unwilling to do a proper job.

    Now the system produces about an 8 degree F inlet air vs outlet air temperature differential (w/1800 cfm of airflow) and the compressor motor seems to start hard. I think I may now have an overcharged system.

    Further reading of the manual reveals that the factory-installed orifice in the evaporator is 0.093 inches, while the condenser has a plastic bag taped to the side with a 0.080 inch orifice. So, my questions are:

    1. Do I need a new AC guy?

    2. Should I have the (new) guy change the orifice from the 0.093 to the 0.080? This will be an extra expense over just having the new guy do a proper coolant charge. What will be the effect if I just leave in the 0.093 orifice? Is the 0.080 even the proper size for my combo?

    3. If I need to change the orifice, should I just have a TXV installed? I'm in the Dallas mid-cities area, and electricity bills from cooling are expensive, so any improvement in efficiency would be a good thing.

    Thanks in advance for the help.

  2. #2
    Join Date
    Jun 2003
    Location
    French Settlement, Louisiana, United States
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    295
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    #1. I think yes if he is charging just by pressure and feeling line. (And if that's the way he charged the unit , makes you wonder if he pulled a 500 micron vacuum ? )

    #2 without the correct office it will never give the desired cooling and could damage the compressor by having liquid refrigerant not all boiling off in the evap. Coil.

    #3 a 13 SEER Goodman usually does not need a TXV. But I have never seen a TXV hurt performance.

  3. #3
    Join Date
    Jul 2007
    Location
    Virginia
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    Yes, you do need a new company or tech. Who knows what other short cuts this guy took - no nitrogen while brazing, no pressure test, no evacuation, didn’t set proper airflow ect. ect……..

    The orifice is sized to the condenser, and the .080 is the correct one for your condenser.

    The refrigerant should all be removed now that it has possibly been overcharged, and the correct amount weighed back in, with a final adjustment by utilizing superheat and subcooling.

    While the refrigerant is out, the piston should be changed, or a TXV added if you want a little more efficiency.
    Instead of learning the tricks of the trade, learn the trade.

  4. #4
    Join Date
    Dec 2002
    Location
    Houston,Texas
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    Quote Originally Posted by WileyCoyote View Post
    Further reading of the manual reveals that the factory-installed orifice in the evaporator is 0.093 inches, while the condenser has a plastic bag taped to the side with a 0.080 inch orifice.
    Whatever orifice the condenser calls for, should be in the evaporator.
    __________________________________________________ _______________________
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  5. #5
    Join Date
    May 2014
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    2
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    Thread Starter
    Thanks again for the help. I'll use the forum map to find a new guy.

  6. #6
    Join Date
    Jan 2008
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    Call the installing company and demand the system be properly set up.
    With an orifice, the charge should be set by super heat. Not by grabbing the suction line.
    With a TXV, charge is set by sub cooling.
    You paid for a professional installation - do not let them skate on this.
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

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