Aluminum to Copper Pressure Test w/ Al-Cop
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You may have used solder rings before. Bryan and Sal essentially make their own solder rings by bending the alloy around the tubing that needs to be brazed. The SolderWeld aluminum coil repair kit comes with small tubes of Al-Cop braze and Alloy-Sol (as well as flux and a brush); it’s a more lightweight alternative to the all-in-one kit that still has everything you need for aluminum-to-copper brazing.
Before swaging the aluminum, Bryan cleans and cuts it for the best possible results. Once the aluminum has been cut, Bryan deburrs it (just as he does with copper) and heats it up a little bit. Aluminum is a bit more prone to cracking than copper, so swaging is most effective when the aluminum has been heated slightly. The swaging process is a success; the aluminum opening is just a bit larger than the copper, so there’s room to pull the solder into the joint.
Once the joint has been brazed or soldered, it needs to cool naturally because rapid cooling can deform the dissimilar metals. After cooling, Bryan proceeds with the pressure test. No soap bubbles show up even at 300 PSI (and even 500 PSI!).
When creating a solder ring for brazing tubing in the upright position, you will want to make sure that the flux faces the metals (when using flux-cored rods). The ring needs to be right, and the ring method tends to be most effective when the tubing is upright.
Again, Bryan allows the solder to get pulled into the joint and lets the joint cool naturally. After that, the pressure test reveals that there are no significant leaks (no bubbles) under 200 or 500 PSI.