What equipment to braze small refrigeration lines

[Jack_K]

I have a project where I need to braze some 1/4" and 3/16" lines in fridges. They are a mix of copper to copper and copper to steel connections. I believe these are the rods that I should use:


The problem I have is deciding on a torch to use. From what I understand, a small oxy acetylene torch is ideal but I'm not certain which size tip is required. Alternatively it would be nice due to cost if a MAP-pro torch would be enough. Apparently MAPP was sufficient but that is no longer made.

An air acetylene torch is an option too.

The short version is that I want to know if MAP-PRO is sufficient for the job. If not, I'm trying to work out the next cheapest solution. If I go with an acetylene option, it will be with full size bottles as I already have them but I need new regulators.

 

[waddycall]

Yes modern Map-pro will do those sizes. We regularly braze and silver solder 1/4 inch fridge lines with it at work. It’s not me who does the job as I only use OA so can’t really comment further other than we use silver solder for copper to steel.

 

[RichardM]

What are you soldering the tubes to?

 

[piman]

Jack,

I use copper brazing rods, which need no flux. Very easy to use and flow well. I don't use them on anything but copper so don't know if they work copper to steel?
oxy acetyene by the way.

Alec

 

[Jack_K]

What are you soldering the tubes to?

Basically switching out fridge compressors. The compressor fittings are steel, the lines are usually copper. Some of them may have steel lines from the old style condensers.

I am switching out 240v AC compressors in household fridges for DC ones. It doesn't usually make much sense but the fridges and donor DC camping fridges were all free.

 

[indykid]

Anything that can get the steel to red heat will be adequate for silver solder. I usually use a handheld propane torch (rothenberger superfire 2 to give you a visual reference) to silver solder and have no issues with heat input on small assemblies like boring bar heads onto carbide shanks or steel widgets, so you should be fine with small tube.

 

[Jack_K]

Anything that can get the steel to red heat will be adequate for silver solder. I usually use a handheld propane torch (rothenberger superfire 2 to give you a visual reference) to silver solder and have no issues with heat input on small assemblies like boring bar heads onto carbide shanks or steel widgets, so you should be fine with small tube.

Part of the problem is getting the heat in quick enough without it going too far and damaging the compressor. It would be great if a propane torch would work as I already have one that uses BBQ gas bottles.

 

[indykid]

If you have more than a couple of inches to play with, wrap a dripping wet rag round the pipe between the joint and the compressor. The conduction down the pipe walls will be no match for the heat extracted by the phase change of the water.

 

[RichardM]

Part of the problem is getting the heat in quick enough without it going too far and damaging the compressor. It would be great if a propane torch would work as I already have one that uses BBQ gas bottles.

This would be my concern too, map will certainly silver solder. Try the propane on a test piece.

 

[Seadog]

I've used MAPP with silver solder when rebuilding a couple of Bambi silent compressors. Oxy propane would heat the job faster.

 

[knighty]

I use oxy propane for brazing refrigeration stuff together

copper-copper joints I use phosphor bronze rods, copper-steel I use sliver solder


I think you'll be ok with a map gas torch.... worth a try on a couple of bits of spare pipe first, I've never used one for it but the stuff I do is quite a bit bigger


do you have nitrogen to purge/flow while you braze? if you don't you'll end up with a load to soot inside the pipe, it ends up in the compressor oil, turns it acidic and kills the system after a while

 

[Jack_K]

I use oxy propane for brazing refrigeration stuff together

copper-copper joints I use phosphor bronze rods, copper-steel I use sliver solder


I think you'll be ok with a map gas torch.... worth a try on a couple of bits of spare pipe first, I've never used one for it but the stuff I do is quite a bit bigger


do you have nitrogen to purge/flow while you braze? if you don't you'll end up with a load to soot inside the pipe, it ends up in the compressor oil, turns it acidic and kills the system after a while

I do have nitrogen. A lot of people don't seem to bother though.