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uninsulated txv bulb

saw a txv bulb on a attic split system with no insulation on bulb on suction line outside of coil so attic heat could affect bulb. system in 5 years and i wrap it and had high superheat. when i put it back to the way i found it with no insulation it worked fine and good readings and superheat. i assume it has worked 5 years uninsulated, i see it and say oh wow needs to be wrapped and then it doesnt respond correctly. i found this on a routine check and they were not having any trouble until i insulated it.any ideas? is there such a type that is this way? is it defective and this is how someone got it to work?? very strange.


  • Empire_2
    Empire_2 Member Posts: 2,343

    Bulb has to be insulated.  Either you have a bad txv or the charge is off.  What was your readings while insulated?  S/C, S/H Head, Suction...  Is your txv adjustable?  Need more info Paul.  W cannot help without the facts...To answer you Q: yea someone probably left it uninsulated so it would work.  Now as a pro, it's your job to correct it.  I'll bet the txv was replaced before because it don't sound like a factory install.  I could be wrong.

    Mike T.
  • don_9
    don_9 Member Posts: 395
    Wide open

    A wide open txv.will give you great efficency but could harm the compressor by slugging the comp with liquid.Funny how making it right as one who knows it should not be that way and then you have to deal with a customer that has gotten use to it working that away..

    The question is do you make yourself happy or the customer?
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