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  1. #1
    Join Date
    Oct 2007
    Location
    south of boston
    Posts
    174

    No Access To Determine Txv Or Md

    hello new to doing residential, and i have a herd time figuring out if a coil is txv or md when it is on top of a furnace which has no access panal, and there is nothing marked on casing of coil. i have been guessing MD , should i guess txv if condenser list sc temp, the a/h i do remove cover to look but its the enclosed ones i cant see which i hate guessing at, any help is appriciated

  2. #2
    Join Date
    Mar 2001
    Location
    North Carolina
    Posts
    428
    no access panel....no numbers?...have snips??..charge customer to find out, if they wish to have it repaired properly, If you cant access it that means it has never been checked and probaby can use a cleaning.
    Last edited by obxtech; 07-24-2008 at 11:52 PM.

  3. #3
    Join Date
    Apr 2007
    Posts
    623
    I am assuming you dont run into this very often, as most evaporators have removable panels. But it shouldnt be that tough, make a hole and take a peak. be sure to mark it on outside once you have determined what its got. Dont ever assume that you have a txv just because there is a sc chart in the outdoor unit.

  4. #4
    Join Date
    Oct 2007
    Location
    south of boston
    Posts
    174
    obxtech

    there is no #s on it i have tried to see, but no markings, i have opened the ones with access panal, i will see what i can figure out next time thanks

    antitfun

    i do run into this often, unfortunately, it sucks on p/m cuase i cant get to coil makes me wonder how any one checked coil, is it wrong to think if its a brass fitting its md and if its brazed its txv or is that just not true, well thanks

  5. #5
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,789
    A TXV is a MD.
    MD= metering device.
    FD= fixed bore metering device, such as an orfice, cap tube, or piston.

    If you "assume" your doing the custmer a disfavor.

    Some times you have to cut an access to see for sure.
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  6. #6
    Join Date
    Aug 2007
    Location
    MN
    Posts
    2,680
    carry some 10x10 patches and cut a hole above the coil and look down with a mirror and flashlight or a camera like the rigid seesnake.
    You can't fix stupid

  7. #7
    Join Date
    Apr 2007
    Posts
    623
    Quote Originally Posted by zombietech66 View Post
    obxtech

    there is no #s on it i have tried to see, but no markings, i have opened the ones with access panal, i will see what i can figure out next time thanks

    antitfun

    i do run into this often, unfortunately, it sucks on p/m cuase i cant get to coil makes me wonder how any one checked coil, is it wrong to think if its a brass fitting its md and if its brazed its txv or is that just not true, well thanks
    What is preventing you access to them. I see very few built into the duct, guess Im glad I work in my area and not yours, And yes some coils do have piston assmblies exterior of the coil case, I assume these are the brass fittings you are talking about.

  8. #8
    Join Date
    Aug 2003
    Location
    Lincoln, Nebraska
    Posts
    1,051
    Around here there are many evap coils installed with no door on them. They are pitsburged shut. There are still companies doing them that way to save over the cost of a cased coil. I hate how they do it as its very time consuming to check the coil. There ought to be a law!

    I also agree that you need to cut a hole to find out which devise you have.
    Its a good Life!

  9. #9
    Join Date
    Jun 2008
    Location
    Las Vegas, NV
    Posts
    224
    I've seen many a/h out here where access isn't available unless you cut a hole to take a peek. If the system is under a heavy load you can watch the TXV 'hunt' on initial startup.

    Barrie

  10. #10
    Join Date
    Oct 2007
    Location
    south of boston
    Posts
    174
    thanks everyone , i do appriciate it, i will carry some patch stock with me, i hate it when i do p/m and i can not see coil to clean it if it needs it,also thanks beenthere for straitening out my verbage


  11. #11
    Join Date
    May 2007
    Location
    DC Metro Area (MD)
    Posts
    3,371
    If a company has to use an uncased coil, then I think they should field install the TXV on the outside to make it easier for the service tech.

  12. #12
    Join Date
    Oct 2007
    Location
    south of boston
    Posts
    174
    i agree ryanhughs or write on it txv or fixed orifice

  13. #13
    Join Date
    Mar 2001
    Location
    North Carolina
    Posts
    428
    Quote Originally Posted by zombietech66 View Post
    thanks everyone , i do appriciate it, i will carry some patch stock with me, i hate it when i do p/m and i can not see coil to clean it if it needs it,also thanks beenthere for straitening out my verbage

    Why?? that just means more money for accessing and cleaning the coil.

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