Method/Materials for Joining Copper & Galvanized Sheet Metal

Date 10-18-2011 16:45

How about a silver soldered joint? When I was in college, a couple dozen years ago, taking HVAC classes we did lots of silver soldering.

By LSimpson Date 10-18-2011 17:44

Is there some kind of technical documentation available or can you point me to someone who can provide it?

By jwright650 (*****)

Date 10-18-2011 18:12

Here is another alternative....to plumb the drain line from the pan. Drill a hole and insert this, and attach(glue) the pvc condensate line to that fitting.

http://www.bramec.com/categories/detail.asp?cat=2035

By jwright650 (*****)

Date 10-18-2011 19:16

http://www.bramec.com/categories/detail.asp?cat=2177 Similar to the pvc version...just need the gasket and locking ring (sweat the copper pipe to the fitting and allow to cool first though)

By jwright650 (*****)

Date 10-18-2011 19:42

Just looked up in the ceiling here at work at the airhandler and they have a galv'd fitting welded to the galv'd condensate pan(they may have sprayed some cold galv'g spray on the welded joint, kind of old and it's not rusted) and then the copper is threaded up on that fitting, and the rest is sweated together for the rest of the run(as far as I can see with my flashlight).

By Lawrence (*****)

Date 10-18-2011 16:52

Welcome to the Forum!

Low temp solder may be possible.

But galvanized is not going to like it. Corrosion, capillary action issues and fume issue are going to be just for starters.

Rivets! And sealant

By LSimpson Date 10-18-2011 17:52

Thanks for the recommendation but don't know how rivets would work on a 1/2" round copper pipe. Curious why corrosion would be an issue if soldered? I've been trying to research this and so far have only found references that state something along the lines of: using solder to join dissimilar metals is a long standing practice. Also, I have to admit I don't know what capillary action is either, but will be looking that up too.

Thanks for your comments.

By Lawrence (*****)

Date 10-18-2011 19:01

My thoughts were along the following line.

Brazing flame temperatures will exceed the melting point of the galvanized coating (zinc). The burning coating will cause contamination of the flux and have negative effects on the flow of the braze (capillary action).

Galvanized fumes are considered unhealthy (see MSDS) and with the mixture of flux and copper to the issue, there may be some very real ventillation and health conserns that would need to be addressed for operator safety.

once the coating is burned away.. That area will no longer have the corrosion resistant properties of the original galvinized product. (base metal).

I have to admit I've never attempted to braze galvanized. These are just some thoughts.

Rivits appear to be right out!

By 99205

Date 10-18-2011 21:39

I've done hundreds of those things in the sheet metal shops I've worked in. Take a little brush, dip in some liquid flux (hydrochloric acid works the best) , brush it on the galvanized metal (not to much). This will etch the galvanizing so that the solder has good adhesion. Get a good tight fit between the mating surfaces, get your soldering iron good and hot (be sure the tip is "tinned" properly) and solder away. Done properly it will be a strong joint.

By Lawrence (*****)

Date 10-19-2011 02:22

Awesome.

Glad my worries were misplaced.

:)