Strictly, sweating means soft soldering, as plumbers do on water lines, while refrigeration joints are brazed with phosphorus-copper or silver alloys at much higher temperatures. In practice HVAC techs say sweat a joint, sweat in a drier, or sweat fittings for both. A good joint needs clean, fluxed or properly fitted copper, even heat, and nitrogen flowing inside on refrigerant lines to stop scale.
Sweat the new drier in, and flow nitrogen while you do it, I don't want flakes in the TXV screen.
On refrigerant lines, use a brazing alloy, not plumbing solder; soft solder joints crack from vibration and pressure.
Also heard as
- sweat a joint
- solder
Related terms
Flowing nitrogen
Running a low flow of dry nitrogen through copper lines while brazing to keep oxide scale from forming inside.
Filter-drier
A canister of desiccant in the refrigerant line that traps moisture, acid and debris.
Line set
The pair of copper refrigerant lines, one insulated suction line and one smaller liquid line, linking indoor and outdoor units.