Brazing HVAC joints w/o flux

Stop by your welding supply co or maybe your plumbing supply and get some sil-fos rods. They come in different percentages of silver. I prefer the 15% silver but the ones with less silver work. Then get a few copper pipe fittings and a bit of copper pipe and try it. One trial is worth a thousand use group opinions. If you use some insulating firebrick to corral the heat, you can use a hand held propane torch.

Dan

It's Sil-Phos or any of a number names similar to that. It's got copper, silver, and phosphorus in it. The Phos makes it self fluxing on copper.

You may need to use flux on the brass to make these work. In fact sometimes these rods need so much heat that the brass will end up melting. Brass fittings are usually silver soldered by the HVAC contractors I know.

My recommendation is the heat the copper fitting then take some pliers and pull a crimp in one side so that it pulls tight around the pipe. If done properly the crimp will be narrow and draw solder properly. It's hard to describe but I do it all the time to make the next larger copper tubing fit the smaller properly.

Wayne Cook Shamrock, TX