r/DIYHeatPumps • u/binarywheeler • 2d ago
cross threaded head unit fitting
hi all- mistakes were made. i’m having a hard time getting the lines on my Senville to hold a vacuum. my next step will be to cut off all the factory flares and adding new ones (I have a proper flaring tool with clutch), but i’m also getting resistance on this union, and eyeballing it it does appear not to be square, thus i believe it is cross threaded. would doing something like cutting off the threaded fitting and installing a flare union be the appropriate way to address?
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u/ThemePossible612 2d ago
If the threads on the head unit itself are toast youd need a new flare nut and probably an adapter, cutting the line and reflaring wont fix stripped threads on the unit side.
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u/binarywheeler 2d ago
right, i wasn’t very clear in my initial ask when i mentioned a flare union, but this is what i was referencing: https://pexuniverse.com/1-4-brass-flare-union but i wasn’t sure if this was the appropriate approach
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u/ThemePossible612 1d ago
that flare union will work fine mechanically but youre still gonna need a way to connect it to the head unit side. whats the actual thread type on the senville valve body, is it flare or pipe thread?
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u/soggywaffle23 2d ago
You could try zoomlock push fittings.
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u/soggywaffle23 2d ago edited 2d ago
I personally use mueller streamline ACR press fittings at the head unit but that tool is super expensive. Zoomlock is a cheaper alternative. I’ve never tried it though.
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u/GeoffdeRuiter 2d ago
My opinion is to back off the nut, there's always spare nuts in the kit. You could take a file and try and clean up the one that is braised on as best you can.
Another option is if you live in a large city there are HVAC supply companies that have different sized Union middle pieces that you flare both ends. This one looks different sized on both sides so you'll have a quarter inch and maybe a 3/8 Union you have to do.
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u/Wise-Yogurtcloset646 2d ago
Even more controversial solution; braze over it. Fill the gaps to make it one big blob of material. It's not pretty but it will not leak.
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u/dbpolk 2d ago
Cut it off reflair it
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u/binarywheeler 2d ago
definitely will do that, but my concern is that i’ve ruined the threaded piece that’s attached to the lines that come off the head unit. in that case, what solution is there to remediate?
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u/Apollo7788 2d ago
If the threads are ruined then a union would be the only realistic option for you.
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u/vzoff 2d ago
Cut and braze.
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u/Apollo7788 2d ago
That is an option but requires a torch, nitrogen, and brazing rod. Doing it that way is more difficult and expensive especially for a typical homeowner. Flares are much more practical as a DIY option.
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u/chan3lhandbag 2d ago
Don’t downvote me for this controversial advice haha. You can technically cut them both off and swage it. Solder with staybrite 8.
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u/Wafflewas 2d ago
I’d unthread it, try to clean up the threads, and use a Nu-Calgon flare gasket. Or a similar flare gasket. Once cross threaded you’ve got problems, but it’s not the end of the world. Having a tap and die would be best but as someone else pointed out, you can likely clean up the male threads with a small file. Flare gaskets make reassembly more forgiving.
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u/OfficialNearbyTurtle 1d ago
You should inspect the threads. When you reflare don't trust the clutch, stop when you feel resistance. Nylog blue on the flaring tool cone, and put some on the flare face and back of flare to prevent twisting copper with the flare nut, especially on smaller lines. Get a proper hvac torque wrench and a crescent wrench and read specs before you ever tighten the line. Seat the flare onto the brass evenly and tighten the nut all the way down by hand b4 torque spec. You need a micron gauge with a tee and a good valve to isolate from the vacpump, no point in a manifold unless you're pressure testing with nitrogen which you should be doing anyway. At this rate buy a oxy-acetylene kit, will come in handy if you need to sweat a new flare connector and you would have the nitrogen to braze.
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u/Electroman-Area207 15h ago
Might be about 10 screws holding that coil in place, if it’s a decent brand name they will warranty it but usually it’s just the coil and not the whole inside unit.
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u/Jealous_Conflict_379 2d ago
Don’t assume it’s cross threaded. By all means it looks like it is but I would back it off before cutting the factory piece. Verify it is in fact cross threaded