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  1. #1
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    Apr 2008
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    Line Set Reuse R22->R410a-Tomorrow!

    Help, please. The 15 year old 10 SEER split AC/NG furnace is ripped out (Ugh! - at least 95 today and tomorrow). The rebuild of the plenum for larger coil and new MERV 11 filter planned. The new York 18 SEER YZH04811C HP and 80% VS YP8C100C20MP11A NG furnace are ready to go. Aspen coil , TXV and mandatory (rebate) UV lights are ready too.

    Really concerned with the cleaning of the reused line set which the contractor proposed. It's buried in the garage floor and snaked through a vent soffit to behind the furnace. The tech seems intent on just putting a vacuum pump on it to clean it and then load up the R410a. What I have heard here at a minimum is a nitrogen flush is required to rid the line set of the R22 mineral oil. Others add an RX11 flush. Please advise ASAP what is required.

    Thank you.

  2. #2
    Join Date
    Feb 2007
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    190
    Of course replacement is best but it doesnot sound like that is a reasonable option. Provided the lines are the proper size, you should be able to blow them out with nitrogen. Carrier also recomends that you install the drier at the airhandler. The r11 flush is a good product. If you are willing to pay for it, then the contractor should not object. if he does you might not have the right guy.

  3. #3
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    Quote Originally Posted by rponson View Post
    Of course replacement is best but it doesnot sound like that is a reasonable option. Provided the lines are the proper size, you should be able to blow them out with nitrogen. Carrier also recomends that you install the drier at the airhandler. The r11 flush is a good product. If you are willing to pay for it, then the contractor should not object. if he does you might not have the right guy.
    Thanks for the quick response RP. I'm a bit confused as to who is obliged to what here. If contractor says "Reuse line set" on the proposal. Didn't say anything about additional costs to do that. What does that oblige him to do? There must be a standard prep of the reused line set, no? But what would be the "industry practice" in this case? He's got a 1 year warranty. Would anything show up in that time?

    PS: This is the tech and not the contractor saying this. The contractor laid out the job and will be back tomorrow, I believe.

  4. #4
    Join Date
    Apr 2009
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    Pan Handle, Fl
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    I agree, replacement is best idea. If you are upsizing checking size of copper lineset is must. If I can't replace line set I flush with the R-11 and nitrogen untill I don't see any more liquid. How long is line set? Why take the chance with this major investment.
    Insanity: Doing the same thing over and over again expecting a different outcome!

  5. #5
    Join Date
    Feb 2007
    Posts
    190
    When 410 first came on the market the manufacturers insisted on lineset changes. Carrier has been in the 410 business since 1996. Last I heard They had 80% of the 410 (PURON) systems. With that extensive track record the have learned that there is not a significant increase in failures in properly installed systems where the linesets could not be changed.

    As far as who should pay for the flush. It is not included in his price. If you want it done expect to pay for the service.

    Your contractor is comfortable with a proper vacuum. I would be comfortable with a Nitrogen flush and the drier installed at the evaperator. If the flush would make you more comfortable then it is worth the money.

  6. #6
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    Quote Originally Posted by Willserve View Post
    I agree, replacement is best idea. If you are upsizing checking size of copper lineset is must. If I can't replace line set I flush with the R-11 and nitrogen untill I don't see any more liquid. How long is line set? Why take the chance with this major investment.
    I would guess 40 feet long. Not a real issue of replacement cost. The garage is finished and access to the furnace is tight with a water heater sitting on the return air plenum with the furnace with a return duct between them. Tight. Also several doors between outside and inside units. Also a 90 degree turn.

    The split AC/furnace was also a 4-ton, But the new HP is considerably higher SEER and the furnace a bit more capacity but not size. It's the 5-ton, high SEER coil that makes the new unit the same size as the old unit. It's huge!

  7. #7
    Join Date
    Dec 2002
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    Arizona
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    RX11 flush is Not recommended by all manufactures. See page 4.
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  8. #8
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    Quote Originally Posted by jimj View Post
    RX11 flush is Not recommended by all manufactures. See page 4.
    Thank you, Jim. Trane at least requires just a nitrogen flush and use when brazing. Even po-po's flushes. Nitrogen seems consistent with most recommendations. I believe others suggest the RX11 flush as an additional procedure.

    I might even read between the lines and conclude that Carrier's position is similar since they don't require (additional?) flushes either.

    In some quick searches, the RX11 flush does appear to be a real cost and I can understand reluctance to do it. But is it unreasonable to expect the contractor to do a nitrogen flush as part of the install?

  9. #9
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    Quote Originally Posted by jerryd_2008 View Post
    But is it unreasonable to expect the contractor to do a nitrogen flush as part of the install?
    Without a doubt. If there not doing a Nitro flush they don't know what there doing.
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  10. #10
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    Jan 2004
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    Just needs a nitrogen flush/purge, to get out any excess mineral oil.
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  11. #11
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    Quote Originally Posted by beenthere View Post
    Just needs a nitrogen flush/purge, to get out any excess mineral oil.
    Thank you, BT. Does a nitrogen flush/purge require a drier as others suggest?

    Jim seems to think that this nitrogen flush is on me (or I could have misunderstood him). Do you? Just looking for industry practice which means to me should be included but seems to be unclear in many HVAC install procedures, no?

  12. #12
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    Quote Originally Posted by jerryd_2008 View Post
    Thank you, BT. Does a nitrogen flush/purge require a drier as others suggest?

    Jim seems to think that this nitrogen flush is on me. Do you? Just looking for industry practice which means to me should be included but seems to be unclear in many HVAC install procedures, no?
    Sorry if you miss-understood me, A Nitro purge SHOULD be included.
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  13. #13
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    Apr 2009
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    Most manufacturers recommend using nitrogen while brazing to prevent oxidation. At a minimum I would do a nitrogen flush, not to split hairs but that trane letter said some flushes are corrosive. That's why you follow-up with a nitrogen chaser.
    Insanity: Doing the same thing over and over again expecting a different outcome!

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