15% or better...pass the blessings ($) along to the customer.
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I prefer Dynaflow by Harris. It costs half as much as Harris Stay Silv 15. Great stuff. Here is Harris's description:
"Dynaflow melts and flows at temperatures very close to Stay Silv 15, and provides comparable brazed mechanical properties. This makes Dynaflow an excellent cost effective alternative to the 15% silver alloys. This premium, medium range silver alloy has been meticulously formulated to even tighter specifications than our standard copper-to-copper alloys."
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Ive always used only 15%, but 15% too high now. Went to dynaflow then 5% I find dynaflow doesn't flow as well as 5%. Cant speak for joint strength but never found a leaking brazed joint unless it was obviously misbrazed ( Bugars and/or gaps) Ive heard the brazing material is stronger than the copper and at the looks of todays copper I believe it!
got free sample sticks of Dynaflow, tried them and dont care for it, it doesn't flow well, it would be good to fill cracks and holes.
Been using Rothenberger S2 rods for copper to copper. (seems to be industry standard here in the UK)
5% for braze in sight glasses and driers.
15% for braze in txv's.
38% (flux coated) for copper to steel or brass.
56% for copper to stainless with special flux.
The S2 rods are about 50p and the 15% ones work out around 14 times that...
I prefer the 5% and 15% rods but have to cut my cloth according to my means
Learned using 0% and never had any issue with copper to copper. Only use 15% for things like RV's & TXV's due to its cost.
What about that stuff that comes on a roll.... looks like solder...... Has it also gone up in price ???
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Harris 15% for most. Harris Stay Brite for dissimilar metals. Between those 2, there's not much that you can't join together reliably.
Doing residential work... most of what I see is CO to CO.
Dynaflow seems to work well... reasonable flow and good gap filling. Temp control is a little more critical (needs to be a little hotter, yet not hot enough to do damage to other things). CLEAN joints are more important with Dynaflow... as it bonds better to clean (read that shiny) surfaces. As with lots of other things... preparation (of the joint) seems as important as the (actual brazing) process.
Anything heat sensitive (TXV, RV, etc), I use StayBrite solder. Even a TXV on a 410 system, if the mechanical fit is sung, I have not had any issues.
Quality work at a fair price with excellent customer service!
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Is it? Think about it like this (not telling your boss what to do) I can braze a joint in half the time using less gas and fewer leaks with 15% than I can with 6%, the chances of having a joint crack upon cool down are increased slightly too. Also, more heat outside the joint = more contamination inside meaning that unless you're using a nitrogen purge, you stand the risk of contamination.
Originally Posted by hurtinhvac
I think if you really look at it, your boss is not saving a dime. Last time I checked, acetylene and labor is getting expensive too...
This in an odd way proves my point, the prep work you speak of does not come free.... I am a firm believer in get it fit, get it brazed and move on. We don't use line sets, so the brazing process for us needs to be as bullet and idiot proof as possible.
Originally Posted by ga-hvac-tech
X2 on the Stay Brite 8, great stuff IMHO, driers, sight glasses, txv's, reversing valves. I can't see how it would ever have an issue... Even with 410A.
If a day goes by and you have learned nothing, I hope you got a lot of sleep.
When I did a bunch of it I always used the 15% for everything. Including dissimilar metals and used Harris Stay-Silv with great results. Only had to carry one product for everything.