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Thread: Hilmor Flaring Tool Question When Making A Flare For R410A System

  1. #1
    Join Date
    Jun 2015
    Middletown, CT

    Default Hilmor Flaring Tool Question When Making A Flare For R410A System

    I am installing two Daiken 9000 BTU Heat pumps which use the R410A refrigerant.

    I purchase the Hilmor orbital flaring tool and have a couple questions regarding making the flare and lubricating the flare prior to installing the line sets and torquing them to spec.

    The instructions that came with the tool clearly state that the tubing stop is moved over the correct hole size and the tubing is pushed up until it hits the stop. I have also read on the internet that some prefer to move the stop off to the side and bring the tubing up until it is even with the top of the stop. I assume they feel that the extra surface area makes a better seal. I've tried both ways and both flares look good but if you put it to the top of the stop the flare is noticeably larger. I was looking for a go/ no go flare gauge block but I couldn't find where to get one or what the undersize and oversize dimensions are. If anyone knows the answer I would appreciate it, or if not, I will just follow the directions that came with the tool.

    Also the Daiken instructions conflict with a Daiken University video on Youtube. The instructions say oil only the mating surface of the flare and in the video the instructor says to lubricate the back side of the flare as well. Which way is correct?

    Also I do not have access to the POE oil used in these systems and also used to lubricate the flare. I was planning on using a thin film of the blue Nylog which is POE oil that has been specially treated to act as a nonhardening gasket/lubricant and is compatible with the R410A systems. Is that correct? I have seen a video where they goop a lot of this on the flare. I am not planning on doing that.

    My goal is to have these units completely assembled and then have a licensed A/C tech do the leak check, evac., and refrigerant fill. If I don't get this right he will have to fix my mistakes and I won't have saved any money which is the whole point of me doing the work. It has to be right the first time.

  2. #2
    Join Date
    Jun 2015
    Middletown, CT


    I found a Daiken service news bulletin that had a flaring specification chart. It states that the correct flare diameter for Class 2 (R410A) is 9.1mm for 1/4" tubing and and 13.2mm for 3/8" tubing. I made a couple flares per the directions supplied with the Hilmor tool and measured the diameter of the flare with a micrometer. They were just slightly under the Daiken spec. If you put the tubing even with the top of the stop it will be much larger than the spec. Also I don't think it will seat correctly in the flare nut.

    In another Daiken document I read that you should use the flare nuts that came on the Daiken units and not the ones on the preflared line sets that I purchased. I have to redo all the flares anyway because the factory flares on the line sets (not Daiken) are terrible so I will swap out the nuts for those provided by Daiken. I mention that because if you think you can just buy premade line sets and throw them on you may have problems with leaks.

    I also found some installation documentation for some other Daiken minisplit models that say to lubricate the the backside and face side of the flare so the documentation is not consistent. I have also found documentation from other manufacturers that say to lubricte both sides of the flare with POE oil for R410A so I guess that is now the accepted method.

    Daiken also recommends triple evacuation of the system prior to charging. Is this standard practice with these types of systems or should I mention that to the AC tech that will be starting up the units?

    I'm a little disappointed that this info is not all found in the installation document that came with the system but had to be found by searching through numerous online documents.

    Update: I wound up setting the the tubing height slightly higher than the underside of the stop on the Hilmor flaring tool. For the 3/8" line you can go to the top of the stop and it will still fit nicely in the flare nut. If you do that with the 1/4" line the flare will be to big to fit properly in the flare nut. About half the thickness of the stop seems to be about right. I figured that the larger surface area of the flare would provide a better seal. I used the blue Nylog on both sides of the flare. I used a standard Snap On ratcheting torque wrench with crow's foot wrenches on it to tighten the flare nuts to spec. There is a calculation that you have to do to find the proper torque wrench setting when using crow's foot wrenches. It can be found online and you don't need to buy the special Daiken torque wrench. I had a licensed AC tech complete the installation. He found no leaks and both systems have been working great for about a month now.
    Last edited by Greg_E; 08-25-2015 at 10:39 AM.

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