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Thread: txv v.s. fixed

  1. #53
    Join Date
    May 2001
    Location
    Kansas City
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    2,729
    Originally posted by mark beiser
    Robo going off the deep end?

    Most of what he said is true to one degree or another.

    The refrigerant charge is much more critical in a fixed metered system. A TXV equipped system can be slightly under or over charged, sometimes even significantly over charged, without making a significant, or even measurable difference in the performance of the system.

    While poor airflow is bad for any system, a TXV is more likely to prevent flooding of the evaperator coil and liquid refrigerant getting to the compressor than a fixed metered system. I have seen ballance port type TXVs loose control of the superheat when poor airflow is combined with other problems in the system though.

    It is a known fact that a TXV provides better protection for the compressor.

    He kinda lost me with the equipment size and more likely to become restricted parts though, lol.
    If a system is over-sized like most a Txv will adapt to the load placed on it. Most Txv's have a screen to protect them from becoming clogged, most pistons don't and can become restricted from small particle's.
    Robo's just stuck in Goodman land.

  2. #54
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
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    14,915
    Oversizing a system with a TXV is just as bad as oversizing a system with fixed metering.

    Almost every piston metered system I have seen has an inlet screen up in the fitting before the piston.
    If more government is the answer, then it's a really stupid question.

  3. #55
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,981
    I don't know why you guys are acting like I am arguing about the virtues of a TXV...I am not. I just don't see why all of a sudden the piston, which has done our industry well, is the bain of our industry to some of you.

    Rather then it being me that has been brainwashed, I'd say it is those who think that there is only one way to skin the proverbial cat that are the brainwashed ones.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  4. #56
    Join Date
    Nov 2004
    Posts
    2,927
    I think the word is "bane"...but I couldnt swear to it

  5. #57
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,981
    Originally posted by jacob perkins
    I think the word is "bane"...but I couldnt swear to it
    No, It may be a pane, but I used my brane, and I am sure it is bain

    OK, I messed up, but it's the first time on this thread
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  6. #58
    Join Date
    Apr 2003
    Location
    the Great Pacific Northwest
    Posts
    607
    Originally posted by RoBoTeq
    Even the bypass tube mechanically connects to the existing schraeder port used for testing all Goodman coils.

    Wouldn't that be the external equalizer, a bybass would be used on a heat pump with a check valve if the TXV is not a heat pump valve that allows for reverse flow.

  7. #59
    Join Date
    Dec 2005
    Location
    Memphis, TN.
    Posts
    824
    Ok, I have a question...

    In another post I read wher Swampfox has 2 TXV's in his system...Quote: "I did install TXV's on each end and a Variable speed blower... seer? maybe 13?"

    What benefit does this provide and just exactly what is he talking about? I have never seen a system with 2 TXV's! Especially if I am reading this right one at the condenser and one at the evap.

    Please enlighten me!

    Thanks,

    Citywide.

    "I don't care what you could get it off the net for, they wont warranty it and neither will I"!

    And if you don't like my "flat rate up front pricing" try and negotiate the price on that big mac you just bought pricing is exactly the same method!

  8. #60
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    That means he has a heatpump with TXV metering at each end. Same benefit as any txv....better performance /protection, even though a HP has an accumulator.
    If everything was always done "by the book"....the book would never change.

  9. #61
    Join Date
    Dec 2005
    Location
    Memphis, TN.
    Posts
    824
    Yes he does have a H/P.

    I will be installing a H/P as well. Please tell me where on the H/P this would be installed and what are the benefits, operation, efficiency, charging tips, use of a sightglass with a dual TXV???, how does this effect heat in the winter? better or worse?, and last but not least... How do you size it?

    thanks,

    Citywide.

    "I don't care what you could get it off the net for, they wont warranty it and neither will I"!

    And if you don't like my "flat rate up front pricing" try and negotiate the price on that big mac you just bought pricing is exactly the same method!

  10. #62
    Join Date
    Nov 2005
    Location
    Texas
    Posts
    1,633

    city wide

    Refrigerant flow in cooling,note that there may be a bi-flow
    expansion valve without an external check valve on either
    end. This is kinda old, but should exhibit the flow.



    Refrigerant flow in heating.




    Hope this helps a little.


    Regards..........



  11. #63
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,915
    charging tips, use of a sightglass with a dual TXV???[/B]


    Generally ignore sight glasses, they are not a reliable way to charge a system.
    If you keep adding refrigerant until the sight glass is totally clear when the system is under a high load/ambient, you probably overcharged the system.
    If you stop adding refrigerant to a system as soon as the sight glass is clear when the system is under low load/ambient, you probably undercharged the system.

    I don't think any manufacturer still makes any residential equipment where charging to a clear sight glass is a recommended, or acceptable, charging procedure.

    A long time ago, some manufacturers did, like Carrier, but the instructuions also required that you block the airflow through the condensor coils enough to maintain a specified head pressure while you charged by the sight glass.
    If more government is the answer, then it's a really stupid question.

  12. #64
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    You need an engineer. As far as I'm concerned, you can never go wrong with a txv.
    If everything was always done "by the book"....the book would never change.

  13. #65
    Join Date
    Dec 2005
    Location
    Memphis, TN.
    Posts
    824
    Originally posted by citywide service
    Yes he does have a H/P.

    I will be installing a H/P as well. Please tell me where on the H/P this would be installed and what are the benefits, operation, efficiency, charging tips, use of a sightglass with a dual TXV???, how does this effect heat in the winter? better or worse?, and last but not least... How do you size it?

    thanks,

    Citywide.

    Ok, I got the pictures and thanks for those...sometimes you just gotta see it.

    So what are the benefits and efficiency of the 2 TXV systems? I assume you still charge with SH/SC so how long do you let the system operate and settle down before attempting to adjust the system charge? And finally and just about most importantly...how will this effect the heating in the winter? Also need sizing info...same as indoor TXV?

    Thanks,

    Citywide.

    [Edited by citywide service on 04-30-2006 at 05:24 PM]
    "I don't care what you could get it off the net for, they wont warranty it and neither will I"!

    And if you don't like my "flat rate up front pricing" try and negotiate the price on that big mac you just bought pricing is exactly the same method!

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