ProPress vs Brazing: Which Belongs on a Refrigeration Line?

This one splits along trade lines. Plumbers press. Refrigeration guys braze. And when a plumber with a press tool picks up an HVAC side job, the first question is always the same: can I just press it?

Short answer: for refrigeration and air-conditioning work, brazing is still the default, and the Copper Development Association says so plainly. Press has genuinely arrived in HVACR — but not with the fittings and jaws in your van.

They are not the same process, and the line between them is a temperature

People use “soldering” and “brazing” loosely, and the trade terms make it worse. The Copper Tube Handbook is blunt about that: brazing filler metals are sometimes called “hard solders” or “silver solders,” and it says these confusing terms should be avoided.

The actual definition is a number. The American Welding Society defines soldering as joining with a filler metal having a liquidus not exceeding 840°F and below the solidus of the base metals. In practice, most soldering is done between about 350°F and 600°F.

Brazing filler metals melt in the range between 1100°F and 1500°F.

So the difference is not technique or skill level. It is roughly a thousand degrees, and everything else follows from that.

Why refrigeration work is brazed

The Copper Tube Handbook puts it directly: brazed joints, made with capillary fittings, are used where greater joint strength is required or where service temperatures reach as high as 350°F, and brazing is preferred, and often required, for joints in air-conditioning and refrigeration piping.

That is not the only place it shows up. The same handbook recommends brazed joints for compressed air systems, and for fuel gas it describes using Type L or Type ACR tube with flared joints in accessible locations and brazed joints made with AWS A5.8 BAg series filler metals in concealed locations.

Refrigeration also uses its own tube. ACR tube is covered by ASTM B 280, carries a blue marking, and is designated by its actual outside diameter rather than a nominal size — the same trap the press world has with CTS and IPS, in a different costume. Its listed uses are air conditioning, refrigeration, natural gas, LP gas and compressed air.

The nitrogen purge is not optional, and it is the part people skip

If you have watched a refrigeration tech braze and wondered why there is a nitrogen bottle on the floor, this is why. The handbook’s instruction is unambiguous: during brazing, the system shall be continuously purged with oil-free dry nitrogen to prevent the formation of scale inside the tubing, and the purge shall be maintained until the joint is cool to the touch.

Scale formed inside a refrigeration line does not stay put. It ends up in the metering device and the compressor. This single requirement is a large part of why brazing refrigeration is a skill rather than a task.

One safety note worth stating plainly, because it is in the handbook and not in most shop conversations: some BAg series filler metals contain cadmium, which can produce toxic fumes when heated. Ventilate properly.

If you work in the trade and want a note when a new guide goes up, leave your email below. No spam, no course funnel — written by a licensed Georgia plumber.

The cost of brazing nobody prices in: it softens your tube

This is the most useful thing on this page, and most people joining copper have never been told it.

Copper tube is sold in tempers — drawn (what the trade calls hard) and annealed (soft). Hard tube carries a higher rated internal working pressure. But heat undoes that. In the handbook’s words: when welding or brazing is used to join tubes, the annealed ratings must be used, because the heating involved in these joining processes will anneal — soften — the hard tube.

So a brazed system built from hard-drawn tube has to be rated as if it were soft tube. A properly designed mechanical joint, press included, does not carry that penalty; the handbook notes the drawn-tube ratings can be used for soldered systems and for systems using properly designed mechanical joints.

That is a real engineering argument for press that has nothing to do with speed, and it is the one you rarely hear, because the usual pitch for press is labor hours.

Press is genuinely approved for HVACR now — with a large asterisk

This is where the honest answer gets interesting. Press-connect is not locked out of refrigeration work. The handbook states that advances in press-connect and O-ring/gasket technology mean press-connect joining is now used for high-pressure HVACR applications rated up to 700 psi operating pressure.

Those fittings get there through some combination of a different O-ring or gasket material, a thicker fitting body, and a changed crimp geometry — in some cases a double, 360-degree crimp to one side of the O-ring.

And here is the asterisk, quoted almost directly, because getting it wrong is expensive:

These fittings, tools and crimping jaws are not interchangeable with standard low-pressure press-connect systems.

Your plumbing press jaws do not make a rated refrigeration joint. The handbook is explicit that care should be taken to ensure only proper, compatible fittings, press jaws and tools are used, and that the fitting manufacturer’s installation instructions are followed. If that sounds familiar, it is the same lesson as choosing between press systems on the plumbing side — the tool is rarely the constraint, the jaws are. We go through that in the M12 vs M18 press tool comparison.

So which should you use?

• Refrigeration and air-conditioning line work → braze, unless you have specifically bought into a listed high-pressure HVACR press system, with its own fittings and its own jaws.
• Medical gas → brazed, with tube cleaned for oxygen service. The handbook points to Types K or L per ASTM B 819 and NFPA 99. This is certification territory, not a side job.
• Compressed air → the handbook recommends brazed joints.
• Domestic water and hydronic heating → this is press’s home ground, and brazing is overkill. The comparison that actually matters there is ProPress vs soldering.
• Concealed fuel gas → brazed with BAg filler per the handbook’s guidance, or a press system specifically approved for gas.

One material note before you plan anything: copper is the preferred material for most refrigerants, including newer natural refrigerants like CO₂, propane and isobutane — but the handbook states copper is not recommended for use with ammonia.

Frequently asked questions

Can I use my ProPress jaws on refrigeration line?
No. High-pressure HVACR press systems use their own fittings and their own jaws, and the Copper Tube Handbook states they are not interchangeable with standard low-pressure press-connect systems. Matching the tube size is not enough.

Is brazing stronger than soldering?
Yes, and that is the point of it. Brazed capillary joints are used where greater joint strength is required or where service temperatures run as high as 350°F. The trade-off is the heat.

Why do refrigeration techs flow nitrogen while brazing?
To stop scale forming inside the tube. The handbook calls for a continuous oil-free dry nitrogen purge, maintained until the joint is cool to the touch.

Does brazing weaken copper pipe?
It anneals it. Hard-drawn tube that has been brazed must be rated using the annealed pressure ratings, because the heat of the process softens the tube. Mechanical joints, press included, do not carry that penalty.

What is the actual temperature difference?
Soldering uses filler with a liquidus not exceeding 840°F and is usually done at 350°F to 600°F. Brazing filler metals melt between 1100°F and 1500°F.

Bottom line

Brazing is not the old way of doing what press now does. On refrigeration, medical gas and compressed air it is the specified method, and the nitrogen purge and the annealing penalty are the reasons it stays that way. Press has a real and growing place in HVACR at up to 700 psi — but it is a separate system you buy deliberately, not a jaw you already own. For the plumbing side of the press decision, start with the copper press fittings guide.

Technical figures on this page are from the Copper Development Association’s Copper Tube Handbook (CDA Publication A4015-26/24).