Tewloss Copper Fittings Kit HVACR 3/8 & 7/8 Line Set, Copper Pipe Fitting Coupling and Elbow, Air Conditioning Refrigeration Liquid Line & Suction Lines Tubing Pipes for Central/Split A/C systems

Why I added this kit to my truck

On a recent retrofit, I had to reroute a 3/8-inch liquid line and a 7/8-inch suction line around a tight joist bay—nothing exotic, but exactly the kind of situation where the right fittings save time. I tossed the Tewloss copper HVAC fittings kit in my bag as a just-in-case backup. By day’s end, it went from backup to go-to. It’s a straightforward, no-frills assortment that covers the essentials for residential and light commercial A/C work, and its mix of couplings, street 90s, and a single 45 got me through a neat, leak-free reroute without a supply run.

What’s in the box

The kit is built around the two line sizes you see most often in split and central systems:

• 3/8-inch (commonly the liquid line): 2 couplings, 2 single street 90s, 2 double street 90s
• 7/8-inch (commonly the suction line): 2 couplings, 2 single street 90s, 2 double street 90s, 1 standard 45

That’s 13 pieces total. The emphasis on street elbows is smart. A single street 90 has one male and one female end, so you can turn a corner directly off a component or another fitting without an extra stub. The double street 90s (male on both ends) are handy for building compact offsets or tightening up runs in cramped utility closets where another coupling would be overkill. I would have loved a second 45, but I can see why they chose to prioritize 90s.

Build quality and finish

Out of the bag, the copper is bright with a smooth, uniform finish. The sockets were free of burrs and the edges were clean—no sharp lips to gouge insulation or catch on deburring cloth. The sizing marks are legible enough for quick identification on the fly. I checked fit on ACR tubing (3/8 and 7/8 OD): insertion depth was consistent, and the slip fit was appropriately snug, leaving a capillary gap that took brazing alloy well. None of the sockets felt sloppy; I didn’t need to pinch or dress a single piece to get the right feel.

The elbows look like standard-radius patterns—appropriate for general installs. If you’re chasing every last bit of suction-side pressure drop on long runs, long-radius elbows are still the gold standard, but for most retrofits and equipment swaps these are absolutely fine. The male ends on the street 90s were concentric and smooth; you won’t fight with alignment trying to get them to nest in a coupling or coil stub.

Brazing experience

I prepped the tube ends with a reamer, a quick pass of emery cloth, and a wipe, then purged with a slow trickle of nitrogen during heat. Using a 15% silver brazing alloy, wetting was clean and predictable. I didn’t see any oddball contamination or sputter, and the alloy flowed around the joint evenly without me having to hover heat on any single spot to coax it. Post-braze, oxide scale was minimal—about what you’d expect with a proper purge.

I built two test joints on the bench first—a 3/8 coupling and a 7/8 single street 90 into a coupling—to check flow and clearance, then moved on to the live reroute. No pinholes, no “runaway” moments where the alloy tried to puddle instead of wick. It behaved like good wrought copper should.

Pressure and vacuum checks

After the install, I pressure-tested the lines to 400 psi with nitrogen for a hold test. No detectable drop over a few hours while I buttoned up other tasks. Evacuation to sub-500 microns went smoothly; the rise test was stable, suggesting the joints were tight and free of significant moisture. That’s the standard outcome I expect from quality fittings paired with clean prep and a purge, and it’s what I saw here.

In the field: layout and handling

This kit is about making everyday obstacles painless:

• Tight mechanical closets: The double street 90s were perfect for a compact offset that needed to clear a panel lip without adding length.
• Service repairs: If you cut out a kink or rub-through, the couplings give you a quick, clean splice without hunting through mixed bins.
• Smoother routing: The lone 45 helped me soften a change in direction on the suction side to keep airflow and oil return happy; I do wish there were two.

Because these are universal ACR sizes, they played nicely with factory stubs, line set tubing, and existing branches. The aesthetic “gold” copper shine is more a nice-to-have than a must, but the smooth finish out of the bag does speed prep. They arrive loose, so as with any copper, store them clean and cap them if they’ll sit in a dusty truck bin.

What I like

• Useful assortment: The ratio of 90s to couplings matches real-world use. The inclusion of double street 90s isn’t as common in small kits and pays off in cramped runs.
• Consistent machining: Smooth sockets, clean edges, and concentric male ends make for predictable brazing and less fuss with alignment.
• Reliable sealing: With nitrogen purge and proper technique, the joints held pressure and evacuated as expected—no surprises.
• Right sizes for common jobs: If you work mostly on residential splits and package units, 3/8 and 7/8 cover a lot of ground.

Where it falls short

• Limited variety: No tees, reducers, caps, or service fittings. If you’re branching or changing tube size, you’ll need additional stock.
• Only one 45: I often prefer two 45s over a single 90 on suction lines to ease flow; having just one limits layout options.
• Unknown standard listing: There’s no stamped callout for common specs like ASME B16.22. The quality is there in practice, but I prefer explicit markings when possible.
• No protective caps: Not a dealbreaker, but end caps would keep interiors pristine in transit.

Who this kit is for

• HVAC techs who want a small, tidy backup stash for line set reroutes, equipment swaps, and repairs.
• Contractors who keep deep stock on the truck but like a pre-bundled 3/8 and 7/8 set ready to grab and go.
• Skilled DIYers replacing an air handler or condensing unit who are comfortable brazing and following best practices (nitrogen purging, pressure testing, proper evacuation).

If your work regularly involves multi-branch systems, oil traps on long rises, or frequent diameter changes, you’ll still want a broader fittings inventory. Consider supplementing with tees, reducers, long-radius elbows, and additional 45s.

Tips for best results

• Always purge nitrogen while brazing to avoid internal oxidation and black scale.
• Deburr and clean both tube and fitting; even a “burr-free” fitting benefits from a quick scuff and wipe.
• Dry fit and mark insertion depth to ensure full engagement during heat.
• Use heat control on 3/8 fittings to avoid overheating thin sections; let the alloy flow, don’t force-feed it.
• Pressure test appropriately for the refrigerant and system rating, then evacuate to at least 500 microns and verify a stable rise test.

The bottom line

The Tewloss kit is a practical, no-nonsense assortment that hits the sweet spot for everyday residential and light commercial A/C tasks. The pieces are clean, well-machined, and sized properly for ACR tubing. In use, they braze cleanly, seal reliably, and make quick work of common reroutes and repairs. You won’t find specialty items in this set, and you may want more 45s, but for line-to-line connections and tight turns, it pulls its weight.

Recommendation: I recommend this kit as a convenient, dependable supplement to your fittings inventory—especially if 3/8 liquid and 7/8 suction are your bread and butter. It won’t replace a full bin of tees and reducers, but it will save a supply run and keep your workflow smooth on the kinds of jobs most of us see every week.