Installing a mini-split in the US. On the indoor units, the liquid line coming from the unit is 8mm, not 1/4, though it has 1/4 flare fitting. Trying to bend the line into position, I've indented the tube slightly. Arrgh. It is very difficult to find 8mm flare fittings in US, much less 8mm to 1/4 reducers. I've ordered some 8mm to 8mm unions from China which will arrive in several weeks. Can I just ignore this ding, or should I wait for fittings to arrive? Or any other alternatives? Don't want to wait that long for ac this Summer.

Edit: Thanks for comments. I edited the subject and added pictures.

Yes, the OD of the smaller line is ~.315 inches. The brand is Durastar, 18k indoor unit.

Is it necessary to fix this bend?

Can I drill out a 1/4 or 5/16 flare fitting and use that?

This is a diy unit, and refrigerant is not released until I turn the allen screws on the outdoor unit. I intend to do my best to follow rules regarding handling of R410A.

Thanks for any help.

Picture of bent liquid line 8mm Other side of bent liquid line

  • A picture of the ding would be helpful.
    – JACK
    Commented Jun 30, 2021 at 17:52
  • 1
    What brand and model are you installing ? 8mm is 5/16 but are you measuring correctly? Tubing is measured on OD not ID, this was really hard for me as an electrician that measures everything by ID when I received my hvac training. If I needed an adapter I would use a swaging tool and stretch the 1/4” up a size this is why you can’t find an adapter most likely really easy to make.
    – Ed Beal
    Commented Jun 30, 2021 at 18:00
  • I would talk to a local HVAC supply, or your equipment manufacturer, and avoid random crud from China (is it even made for HVAC systems?). Also respect your local laws regarding freon handling... almost every country has restrictions due to their signing of the Kyoto Protocol. Commented Jun 30, 2021 at 18:55
  • From the angle of the photo the link in the liquid line is fairly severe, how are you going to evacuate the system and leak check prior to charging? Did you know the EPA can levy fines up to 25,000.00$, I have a friend that was turned in by a neighbor he had a 609 license and had his 608 level 1 prior to the court date so he did not have to pay his fine FYI.
    – Ed Beal
    Commented Jul 1, 2021 at 0:57
  • I will pressure test with nitrogen, then use a vacuum pump to complete the testing. As far as I know, this can all be done without handling any refrigerant. Some DIY mini-split systems are sold pre-charged, with the intent that homeowners can 'do-it-themselves', and my research thus far seems to indicate that I can do this without running afoul of any regulations. If you have information that contradicts this, please let me know.
    – scott
    Commented Jul 1, 2021 at 2:20


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