Hey you found the podcast. It was hopefully not too difficult to find because you can listen to it a lot of different places, including our new app. You can find on Android or iPhone, but you found it and today we're talking about how to braise or solder anything, and this episode is brought to you by solder. Weld solder well makes a great line of products specifically for the HVAC industry.

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If you want, but today we're talking about how to raise or solder anything and just some of the things you want to think about, and so I'm not going to go over the techniques for every specific type of brazing application. But rather, let's talk about the things you need to know. So what are some of the things you need to think about? So first thing to think about is the base metal that you're going to be working on and when it comes to working on different types of base, metals, certain base metals, don't work with certain types of fluxing agents, so you have to have a flux. That's going to match both the temperature and the base metal and probably the best example of this is that we use phosphorus in rods like our 50 percent, 5 %, 0 %, foz, copper rods that we use or SIL Foss rods.

They have phosphorous in it. So if there's false in the name, you know it as phosphorous and steel doesn't work with phosphorous, they're, not happy. They don't react properly. So, while copper, copper to copper, we don't need to use flux.

You know this. If you're connecting a condenser, you notice, you don't use flux, that's because the phosphorous inside those SIL foster foster rods, dad's the fluxing agent, and so you don't need flux. But if you're gon na be working with steel, then you can't use a phosphorous rod. You use a high silver rod and then you use a separate flux, so you need to know some stuff about just the basic properties of how your base metal is flux and flux.

Just means kind of acts as a cleaning agent. It helps to absorb or counteract oxides that build up as you heat the base metals, and so it kind of keeps it clean and allows that solder or brazing alloy to bond also quickly. A lot of people wonder what the interesting brazing and soldering is, and it's just really temperature. When you get above, I think it's 850 degrees, it's either 850 or 860.

Then it's brazing and when you're below that it's soldering. So it's just the temperature either way you're using a alloy or a separate metal that is not the same as the base metal or either of the base metals, if you're joining two dissimilar metals together for those of us who are used to working with copper, copper Has some really nice properties for joining and it's very conductive of heat, so you can kind of heat in one spot and the heat travels all the way around the copper, which is why, if you've ever worked with soft solder and you'll notice that you don't even Need to wrap the solder around you just heat the pipe get the flux to the right temperature and you just push the solder in and it wraps all the way around the joint. So that's one of the characteristics of soft solder is that you don't have to work it around the way that we typically have to when you're working with silver solder and that's because copper is very conductive. So it moves heat.

And so when you're, comparing other types of metals, really almost no metals are gon na, be as conductive as copper that we work with, obviously, if you're working with gold or silver, but we don't do that. So if you're working with steel, for example, steel is not nearly as conductive as copper, and what that means is, is that when you put heat in one spot, it's going to localized in that one spot and you'll notice that with steel, when you put heat in One area it kind of gets hot in that one area it doesn't spread out as much so you got to move the torch a little bit more when you're working with steel or you just apply the heat to the copper and then that kind of conducts it Into the joint, and so there's just different factors with connectivity - and you want to think about that is how does that heat move with the metal that you're working on the other thing is to think about expansion and contraction. When you have certain metals that expand more than others or expand less than others, then that's going to impact them as you braise, the joint. So, if you're working with something like copper to steel, when you keep the copper, the copper is going to expand, more or brass, is going to expand more than the steel, and so you want to think about that with your joint clearances.

Is that as you heat it, it's gon na spread out and it's gon na get tighter together and in general, we like to think all right. Well, you want as tight a clearance as you can possibly get you want. It really really tight. Well, sometimes you actually don't want it too tight, because then that restricts the capillary action, because the goal, what we're trying to accomplish when we're, soldering or brazing, is we're trying to draw that base metal into the joint we're trying to get it all the way in There - and we don't want to get too much because in the case of some types of solder's, they can actually pull in and kind of puddle inside the line.

And then you'll have these little beads that are inside the tubing and that's definitely no good with HVAC and plumbing. You can deal with a little bit of that, but in HVAC we don't want any of that solder going inside the line so depending on the type of solder. That's a really important consideration. You want it tight in some cases, you don't want it too tight in some cases, if you have it too loose you're gon na pull more material into the joint which is going to cause contamination or bleeding inside the line.

So those are all things that you have to think about as well before you start making a joint that you're not used to making in copper the most common mistake that we make when brazing is just not getting things hot enough, and so with copper, brass and Steel, we have this indicator as you heat it. The base metal changes color and it gets to what we call cherry red and cherry red is generally between 12 and 1,300 degrees in both steel and copper, and so, when you get it to that temperature, that's about the perfect temperature to flow most silver solder. Most of them are somewhere between 1100 and 1250 degrees in that range, that's about the perfect range, and so you want to get it to that temperature, and then you want to kind of hold it there. You don't want to get it too hot, and you don't want to let it cool down too much, because you want that solder to draw into the joint, not just create a cap weld a lot of technicians.

They essentially put the flame right on their rod and they just sort of melt little bridges of solder on top of the joint and they think that's a good-looking joint when they have a nice little pretty cap or fill it on top and they'd haven't necessarily gotten The entire joint hot enough brings us to our next point. You got to know the melting temperatures of your base, metals or at least you're. Generally speaking, what the melting temperatures are? You don't want to get them over the temperature that they might melt, and so, as an example, we'll just give you some basic ideas here. You've got steel that doesn't melt until 25.

Degrees, copper is about. 1950 brass is a little less than that, but then you have aluminum that it can actually melt at under 1,300 degrees. Aluminum doesn't give you that indication of color change, like the others do, and so, if you're, working with aluminum to copper, for example, you'll be heating up the copper thinking that everything's all dandy and all of a sudden, your aluminum is just gon na disappear on you And that's why you've really got to think about what are your indicators for temperature change and with those lower temperature solder's, lower temperature, brazing alloys? Usually it's the flux that gives you that indication. If you're working with silver, like if you're doing, copper to copper, then what you're gon na do is get it to that cherry red that deep red, not bright red, but just that deep red.

And then that tells you that you've got enough heat to draw in your solder start applying it, but with aluminum to copper, say or even if you're, using a low temperature solder like, for example, Multi salt made by solder, welds great solder. But it's very low temperature, and so when you're down in that 600 degree range for the 600 degree range you're not going to get that indication with a temperature change on the metal. So you're gon na have to rely on the flux. And so, let's talk a little bit about flux, there's different types of fluxes.

The first thing to think about with flux is what is its temperature range? Every flux is going to publish here's the working range of that flux. You have to compare that to the melt temperature of the alloy that you're going to be melting and those two need to kind of match up, so that when that flux goes flat and clear, that's usually when you're ready to apply that's almost fluxes work. Some change to like a caramel color depending on the type of fluxes, but they all have an indication that this is now you're in that temperature range and now it's time to start applying the rod most fluxes have some water in them, especially if there are liquid Flux and so you'll see that first 212 degrees that'll boil off and then it'll change a little bit more it'll kind of go syrupy and then it'll go flat and clear or maybe a caramel color with some liquid fluxes. And then you know you're ready to apply that rod, and so at that point the flux becomes the indicator, and at that point you also don't want to overheat the flux.

If you burn that flux well, now, you've got to start over because that flux is now gon na act as a inhibitor to your alloy or your solder actually bonding. So it's kind of touch based on what we've got here so far. You need to know the Mel point of your base, metal, at least generally. You need to make sure that your rod is appropriate for the base level and you need to know something about when that rod flows out.

If you're using a flux, we have to know, do you need a flux or not most cases you do unless you're doing copper to copper. Copper to copper is one of the few cases where you don't need it, but most other applications. You are going to need it so then you're gon na need to know what is the operating temperature of the flux and what are the visual cues and then finally - and I've already mentioned, this - is applying the right amount of material with the right gap. The right clearances so that it's tight not too tight the proper amount.

Usually you want things to be really clean. There are some exceptions to that, but in most cases you want it to be really clean. You want the surface to be scuffed up, and then you want to apply the right amount of material, but not so much that it's going to pull into the joint biggest mistake that I generally see is where technicians do not get the entire joint to the proper Temperature before they start applying rod - and this is especially true with low temperature solder's, where they start applying it and it starts bubbling off, you've got to get that flux to the right temperature before you start applying. The next thing is thinking about where you place.

Your heat, so as a perfect example, if you're working with aluminum to copper, copper is a little bit more conductive than aluminum. It's also the higher temperature of the two, so it's the one that can tolerate the heat a little bit more. So what I usually do is I'll apply my heat onto the copper, a little ways away from the joint until it starts to kind of flow at the joint, and now I can move it over and draw it into the aluminum. It just helps protect that aluminum.

So that I'm not applying heat on just a single spot in that aluminum and potentially burning through it in general, when you're working with different materials, you usually want to apply a little more heat on the copper, because it is a little more conductive. The challenge just becomes that in some cases like when you're working with steel, because steel doesn't have that conductivity in order to get the heat all around it, I do tend to work with the steel kind of around the steel just so that way, you are making Sure that you're getting the steel to temperature all the way around, because again it's going to be more prone in the case of steel for the steel to stay cooler, because it doesn't have that conductivity. So there's a lot of different factors here, but the main point, the end of the day, is to get that entire joint to the proper temperature. That's what you need to accomplish, not just the one side, not just the other side, but the entire joint to the proper temperature, whereas most technicians, they start to focus on just that edge.

It's never just the edge that training camp you're always trying to pull into that joint if you're, making a patch on something like you're, making a patch in a existing coil or something where you're not actually doing a full joint. Well, that's a little different because now, at that point you really just are laying solder on and that's just sort of bonding to the base metal. That's the case with alloy saw you can make a really strong bonded patch on an aluminum rub out and now at that point it's a little different technique. But in most cases, what we're doing is we're trying to draw it into a joint where we have a fitting a coupling and a tube, and you need to make sure you get that whole thing to the right temperature and you got to take account of the Melt temperature and the working temperature of your rod, the melting temperature and the kind of the critical temperature of your base metal, the visual indicators, your base metal does or doesn't give you does it change colour? Doesn't it and then also think about what flux you're using? Is it the right one and what is the working temperature of that flux just a lot of things to think about? But if you think about those things - and you know what you're doing then, even without a lot of experience, you're generally gon na go in and make a decent bond, it may not be beautiful, but it's not gon na leak and that's a key thing.

So hopefully that helps thanks for listening. We will talk to you next time on the HVAC school podcast and oh by the way, if you're interested in what solder world has to offer, go to products by pros.com and find out more have a good one.