🧰 Hello Friends!
It’s Tony.
You can have the finest R-32 packaged unit on the block—efficient, quiet, top of the line—but if your line set install is sloppy? You might as well leave the tools in the van. I’ve seen systems running at half their efficiency—or worse, shut down with catastrophic leaks—all because someone cut corners with the line set 😤.
In this blog, I’m breaking down everything you need to know: sizing, routing, flare connections, insulation, and why R-32 changes the game. If you’re thinking, “It’s just two copper lines,” then pull up a chair—we need to talk.
1. 📏 Size Matters: Get Your Line Set Right for R-32
R-32 has higher pressure than the old R-22 or even R-410A, and it’s got different viscosity and mass flow rates. That means the line set sizing has to be on point—too small and you risk velocity issues, too large and oil return goes out the window.
Check the manufacturer’s specs and confirm:
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Suction line and liquid line size for your exact model
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Maximum and minimum line set length
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Allowable vertical rise/drop (especially for rooftops)
One solid resource here is ACCA’s Manual D and refrigerant piping standards, which outline correct pipe sizes based on capacity, length, and pressure drop.
✍️ Tony Tip: Always oversize the suction line insulation—not the pipe—and keep your bends gentle. Kinks = callbacks.
2. 🧯 R-32 = Higher Pressure = More Precautions
R-32 runs at about 20–30% higher pressure than older refrigerants. This is NOT the place for leftover R-410A line sets you yanked off a job two summers ago.
Your copper needs to be:
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ASTM B280 rated
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Seamless, refrigerant-grade
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Cleaned and capped at both ends until install
And don’t even think about compression fittings here. You’re using proper flare connections with torque wrenches or brazed joints using oxygen-free nitrogen for purging. The ESCO Institute has a great breakdown on flaring and brazing A2L systems.
🔥 Bonus: Most manufacturers require nitrogen brazing to maintain warranty and avoid internal oxidation. It’s a pain—but it’s the standard now.
3. 🥶 Insulation Isn’t Optional
Let’s talk sweat—specifically, the kind that forms on poorly insulated suction lines and ends up dripping into attics, wall cavities, and breaker boxes (ask me how I know 🙄).
For R-32, insulation is critical because:
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The suction line temperature is cold enough to create condensation
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R-32’s flammability class (A2L) makes it even more important to prevent unintended reactions
Use closed-cell, UV-resistant foam insulation with:
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A minimum R-4 rating
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Airtight seams (use mastic tape or insulation glue)
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A vapor barrier if it runs through humid spaces
The U.S. Department of Energy recommends sealing all penetrations around line sets entering the building envelope. That’s both for energy efficiency and safety with refrigerants.
4. 🕵️ Leak Test Like Your Reputation Depends on It
Because it does.
Leaks in R-32 systems aren’t just annoying—they can be dangerous and put you out of code. A2L refrigerants require specific leak detection and evacuation protocols.
Here’s my standard leak test checklist:
✅ 300–500 psi nitrogen pressure test for 20+ minutes
✅ Soap test all flare and brazed joints
✅ Use an A2L-rated electronic leak detector
✅ Evacuate to 500 microns and hold for 10 minutes
✅ Log the data—every time
The EPA SNAP Program also mandates leak detection requirements in certain installs, so brush up if you're in a state with stricter local codes.
🚫 Don’t skip this step just because the pressure holds for 5 minutes. Tiny leaks will come back to haunt you in August.
5. 🔧 Route Smart, Seal Smarter
When you're running a line set for a packaged unit—especially rooftop or ground-mounted—you’ve got to think long-term:
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Avoid low points in the suction line (that’s a trap for oil)
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Support the line every 4–6 feet with UV-rated brackets
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Use a weatherproof sleeve or chase for wall penetrations
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Seal both ends with fire-rated caulk or foam
For outdoor sections, I like using ArmaFlex Black Lap Seal—it holds up against sun, weather, and contractor abuse.
Tony Rule: “If it sags, snags, or rubs—it fails.” 🛠️
6. 🧠 Don’t Skip the Training – Stay Sharp, Stay Legal
Let’s be real—R-32 isn’t your granddad’s refrigerant, and line set installs in 2025 aren't just about bending copper anymore. With A2L safety rules tightening up, training isn't optional—it’s your license to work.
You should be clocking time in:
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Manufacturer-specific R-32 install courses
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A2L certification modules
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Local AHJ code update briefings
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Safety refreshers on brazing, torque specs, and leak detection
A lot of guys are still relying on what they learned 10 years ago. That doesn’t fly anymore. In fact, ASHRAE now offers dedicated A2L handling resources that explain everything from installation zone limitations to line set compatibility.
Also worth noting—some states and municipalities have started requiring proof of A2L safety training for permit approvals. Don’t let a $30 course be the thing that holds up your whole install.
🎓 Tony Tip: Take a course before the season ramps up. Beat the crowd, get certified, and be the one contractor your supplier actually returns calls to in July.
🧊 Final Thoughts – Keep It Tight or Don’t Bother
Listen—line set work might not be glamorous, but it’s where the real pros shine. If you treat it like an afterthought, you’ll be back out there in a month chasing down leaks or explaining why your customer’s bedroom ceiling just got soaked 🫠.
Do it once. Do it right.
Size it correctly. Use the right copper. Seal and support it. Pressure test the hell out of it. That’s how you keep your installs clean, quiet, and rock-solid—even when the summer hits 100°.
And when you're ready to install packaged systems that were built from the ground up for R-32, check out The Furnace Outlet’s full lineup of residential R-32 packaged ACs. These units are designed with line set efficiency in mind—so your craftsmanship actually gets to shine 💪.
Want to know more about Packaged AC Service Disconnects? Visit my guide, Break the Power, Not the Rules.
Catch you on the next rooftop,
—Tony 🧰🔥
