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Thread: why a 50' 1/4

  1. #1
    Join Date
    Jun 2005
    Location
    Winston-Salem NC
    Posts
    1,133
    Came across an old 25+ Lennox HP today. No cooling. Checked and it had the usual dirty OD coil, dirty ID coil and a filthy metal mesh filter laying in the bottom of the return. After cleaning, it wasn't even attempting to sweat back, so put my gauges on it and it was 270 and 72, on a 90 deg day. Did a temp drop and had 15 deg drop across the unit, couldn't get it right across the coil. So it was cooling, but not sweating. Got to looking around the evaporator and noticed with my hand that the liquid line felt cold and wet. Traced it back and it was about 50' of 1/4" cu, and was coiled in about a 2'dia coil. Half way round is where it started sweating and feeling cool, but as I went back along the lineset, the liquid line got warmer and warmer. I remember, sort of, an old service manager of mine telling me something about coiling a liquid line, but can't rightly remember what it was and what it pertained to.Finally shrugged shoulders, said it was cooling and left.
    Any ideas?

  2. #2
    Join Date
    Apr 2003
    Location
    Eugene, Oregon
    Posts
    1,209
    Finally shrugged shoulders, said it was cooling and left.
    Any ideas? [/B][/QUOTE]

    Sorry but you need training.
    Proud supporter of Springfield Millers and Oregon Ducks.

  3. #3
    Originally posted by stonewallred
    Finally shrugged shoulders, said it was cooling and left.
    Any ideas?
    Do you have nobody you can call for help?
    (co-worker, boss, distributor, tech rep)

    At least, you could have told them you needed to look into something and get back with them!

  4. #4
    So the stats so far...

    SP 72/42
    LP 270/122
    AT 90
    Delta T 15

    ST ? SH ?
    LT ? SC ?

    IDB ? IWB ?

  5. #5
    Join Date
    Nov 2003
    Posts
    125
    Didn't Lennox use the 50' coil of copper for their metering device back in the good ol days?

  6. #6
    Originally posted by bbk
    Didn't Lennox use the 50' coil of copper for their metering device back in the good ol days?
    Well, yeah... I don't think you were supposed to let the cat out of the bag just yet.

  7. #7
    Join Date
    Jun 2005
    Location
    Winston-Salem NC
    Posts
    1,133
    Probably need more. Came into HVAC through the backdoor. Started doing Industrial/Commercial maintenance about 19 years ago, everything from the drain in the warden's bathroom sink is stopped up to the motor on the the 14' brake is not coming on line to the transformers on the lines that the state owns need changing to guardhouse number 5 has lost power. Along the way I picked up the knowledge to fix HVAC/R stuff that was under my care. Then I left that fine job and went to work and school to do refrigeration. And somehow I have slid into HVAC. It was cooling when I left at 10:00am this morning and it still is as of a few hours ago, stopped by around 3:30 and checked. ID air temp has came down to a comfortable 74F, and it still is sweating on the liquid line, still not sweating on the suction and it's down to 68 and 265 on pressure.
    So the sucker is working, just don't understand the long coiled liquid line.

  8. #8
    Join Date
    Nov 2003
    Posts
    125
    attaboy Dave

  9. #9
    Join Date
    Jun 2005
    Location
    Winston-Salem NC
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    1,133
    Originally posted by bbk
    Didn't Lennox use the 50' coil of copper for their metering device back in the good ol days?
    So the coil is bascially acting like a long cap tube?

    Never seen it before, but have seen it on plently of reach-ins, just a whole lot smaller.

    But never seen a cap tube sweat before. Wonder if that's due to size or dry ambient air that is usually around cap tubes in small coolers?

  10. #10
    Join Date
    Jun 2005
    Location
    Winston-Salem NC
    Posts
    1,133
    Originally posted by jultzya
    Originally posted by stonewallred
    Finally shrugged shoulders, said it was cooling and left.
    Any ideas?
    Do you have nobody you can call for help?
    (co-worker, boss, distributor, tech rep)

    At least, you could have told them you needed to look into something and get back with them!
    Please, I made sure it was actually cooling before I said anything to the HO, then told them it needed to reach proper ID conditions before I could make sure it was charged correctly and then gave them the option of me hanging about for several hours while it did so, or I could stop back in later and check then.

  11. #11
    Originally posted by stonewallred
    Originally posted by jultzya
    Originally posted by stonewallred
    Finally shrugged shoulders, said it was cooling and left.
    Any ideas?
    Do you have nobody you can call for help?
    (co-worker, boss, distributor, tech rep)

    At least, you could have told them you needed to look into something and get back with them!
    Please, I made sure it was actually cooling before I said anything to the HO, then told them it needed to reach proper ID conditions before I could make sure it was charged correctly and then gave them the option of me hanging about for several hours while it did so, or I could stop back in later and check then.
    OK, one more BOZO to the list!!

    I asked for information to HELP you, you didn't offer any of the needed data...

    You come here and state that you stopped back by and looked at the system and it was still cooling...
    And, if you think it's normal for the liquid line to sweat, then you are clueless! (and that's the FACTS!!)

    Which says it all!! You need training, just like millerman said in the first reply!

  12. #12
    metering devices can be fun

  13. #13
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,915
    Lennox used to use the liquid line as the metering device. Lennox called it the "RFC line". It isn't actually 1/4" copper. There are several sizes and lengths, depending on the size system. If the RFC line is longer than the distance between the indoor and outdoor units, the remainder is left coiled up.

    The last 10-15 feet of the RFC line is suposed to be insulated, because it is normal for it to sweat.

    You can replace the evaperator coil and reuse the RFC line, just leave the piston out of the coil.
    If you replace the outdoor unit, you have to run a new liquid line and replace the indoor coil though.

    Any systems still out there that have a RFC line are old enough that the entire system needs to be replaced if any of the equipment has failed.

    [Edited by mark beiser on 07-05-2005 at 07:58 PM]
    If more government is the answer, then it's a really stupid question.

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