Brass to Copper

[stryder]

Guys...need a few suggestions. Got a 20 ton TXV 7/8 in and 1-3/8 in, anyway...the exsisting one was heated, in my opinion not very much and was rather easy to remove. Problem is when trying to install the new one having problems joining the brass to copper. Might even been discussed before, again any help would be welcomed. Don't think I got enough room for a compression fitting. Oops...before you ask the brass 1-3/8 fitting is the back of the distribution header....Later

[coolwhip]

I think you need to use some sand cloth, stay silv. with brazing flux, and safety-silv 40. Its a 40% silver brazing alloy. Peace.

[sparks]

If your using a 15% It won't happen. I would suggest brazing with 40% silver wire and lots o flux. Also I'd use oxy/acetlyne.

[stryder]

Thanx guys...will be back on the repair probably Tues/Wed will keep you posted...by the way...it was 7/8 in and 1-3/8 out...my bad...Later

[hvacbear]

You have to use silver solder flux or it won't work.

[drsuperheat]

According my Harris handbook it should be Stay-Silv 15% and and Stay-Silv white flux. I made the mistake of using 45% on copper lines into bronze valve years ago and it didn't work. I had to take it apart and start over with 15% and flux, then it was fine. Roger

[coolwes]

What I learned back in the dark ages was:

Copper to steel or brass use 45% silver with the proper flux.
Sil-Phos and other 15% stuff was for copper to copper, without flux.
I know you can make it work on the other combinations with flux but it was originally for copper to copper.
I have seen some crummy brazing jobs where techs mis-applied alloys.

Now the issue of txv's:
I personally like to use soft solder (Stay-Brite #8 or equivalent) to connect the valve to the distributor. I have never had a problem with this and if the valve ever has to be removed it lessens the chance of burning up the distributor. I have seen techs even melt out distributor tubes while trying to remove a txv.
jmho.

[maddfridge]

had to do 2 inch and one eighth copper to cast last week used silver solder suggest that and agree with other replys

[bjefferson]

15% braze is for copper to copper,or copper to brass W/ white brazing flux.You can use 45% with any of it.Its just cheaper to use 15%Soft solder is not suposed to be used on any refrigeration.I know they did it for years,but that dont make it right.

[pincheal]

Stryder,
I've had really good luck with Stay-Brite #8 Silver bearing solder. The way I do it is get the fittings really clean with sand cloth or wire brush, I then use Stay-Clean liquid soldering flux (red Bottle) and use low heat to draw in Stay-Brite solder. Works great to close gaps to .005" and will hold up to vibration and high pressure and is recommended for refrigerant use.
check it out: http://www.jwharris.com/jwprod/solderalloys/#SBSolder
Good luck!

[service guy]

I like Stay-brite I used to braze them in but I found that requires way to much heat Stay-Brite is the way to go. Oh and don't forget clean, clean, clean!!!!

[air1]

I was taught never to use soft solder in a refrigeration system. I now question that wisdom. The pressure rating of Stay-Brite is more that enough to handle the pressures found in most refrigeration systems.

One problem you may be having is that if soft solder was originally used and you didn't clean it all off, your silver solder will be contaminated and you will not get a good weld. You stated that it came off easy and that may be why.

When brazing large fittings you need alot of heat. If the solder is globing and will not flow you need more heat. Use oxy- acetelyne with a tip large enough for the job.

[sparks]

I rarely use stay brite on refrigeration, only if I have to. But, that's just the way I do it, I think it's too easy to overfill the joint and get those little slag peices through-out your system or jam up a cap-line.

When I have used it though, it held up just fine.

Just my .02