Cheap Preheater Idea?

[SeanD]

I'm thinking of saving a bit of time and $ by converting one of my steam pans to a preheater by drilling a hole through the side and putting a threaded ball valve on so that the preheated sap can drip into my pan just like some of the real ones do.

I would hold the valve on with a couple of washers and a nut. Can a compression fitting like this withstand the heat? Does brass react with sap or should I look for SS options?

[gmcooper]

I saw a factory made one years ago very similar to what you describe. The compression fitting would work as your exposure is to the steam and sap not the fire box.

[RileySugarbush]

Yes, that should work fine. Or if you want you can easily solder in a copper fitting from the hardware store. Just use liquid flux and clean the parts first. Use some lead free solder and very low flame on a propane torch.

With that type of preheater, make sure the condensate doesn't drip off the bottom and back into the pan or your are wasting effort.

[SeanD]

That could be easier. I didn't think I could solder two different metals without some major know-how. I have sweat pipes in my house. Are we talking the same skill level?

Should the copper fitting be a short threaded pipe for a removable valve or should I simply solder the valve right to the pan?

I'm actually hoping to sit this pan on some bricks that raise it above the back of the evaporator pan. All my pans together end up 4" shorter than my block arch, so I was going to sit the preheater above this open space. I haven't tried it yet, but I think it will work. It seems like a waste to let that last few inches of heated space go up the stack.

[mfchef54]

sounds like a great idea. What will you use to cut the hole?

[SeanD]

I have a set of hole saws. I'll have to double check, but when I got them, I think they were rated for cutting metal.

[RileySugarbush]

What I have done is use a copper sweat to pipe thread fitting and cut a hole so that the outside of the fitting fits through up to the hex. Then solder it around the fitting. If you can tin a layer on to each part ahead of time it works best. Then thread on a ball valve.

For cutting the hole thin sheet metal there is a great thing called a Unibit that you can get at a local hardware store. They are expensive but do the best job of cutting sheet metal and I find them very useful. Each one can enlarge a hole to several different diameters. The following link will take you to some photos of when I made a flue pan out of a steam table pan in my old setup. I was using a punch for the holes but the soldering is the same.

http://web.mac.com/jabushey/iWeb/Riley%20Retreat/Sap%20pan%20construction.html

[Sugardaddy]

Riley,

I remember seeing that thread with those pictures earlier. very nice! 2 questions, if you don't mind:

1. How do you avoid a burnt sugar line with your pan all the way in the firebox like that? Guessing you keep adding sap.

2. Can you elaborate on how you flared the copper pieces? I don't understand the pipe/plate picture, but it may just be the perspective.

Thank you,

Ed

[WESTVIRGINIAMAPLER]

Hole saws rate for cutting metal is totally different than cutting stainless. Stainless is about 10 times as hard to cut as regular steel, even very thin grades. Key is to go very slow and keep the bit cool or you can burn up several bits before getting a hole in the stainless.

Been there and done that.

[RileySugarbush]

Ed,

I don't use those pans any more, but they sure worked great while I did.

I never worried about the burn above the sap levels. Think of the old iron kettles. In my back pans it wasn't much of a problem since that was pretty dilute at that point. the front pans , with out the flue tubes, were effectively syrup pans and by the end of the day they would be charred black about the syrup. After filtering you would never have known, I've even made light syrup in them! The only problem is cleaning them and that is not that bad. Scrape off the loose stuff and let them soak with dilute muriatic acid (careful!) or full strength vinegar.

Here is how I made the flue tubes. The arresters came with a 1/2 inch end that needed to be cut off. Then the 1" open end needed to be flared 90° to solder into the holes in the pan. First I got them started by pounding them down onto a hydraulic fitting I had that had a 37° flare on it. That was just to get the flare started. Then I wanted to finish the flare in the pan so it would fit tight against the bottom of the pan. I drilled a 1" hole in a quarter inch aluminum plate, set it on a pipe and then dropped the pan with tube through and bounded the flare flat. I'm sure there would be an easier way, but it worked ok.

The trick to soldering them was very low temp flame. I didn't have a big soldering iron, that would have worked better.

[Sugardaddy]

Danka! Sounds like quite a project!

[SeanD]

Thanks for the advice, guys. That unibit looks good, but you're right, it's expensive. There are some cheaper equivalents on ebay, though. I may give the hole saw a shot first and see where that gets me (or doesn't get me).

[SeanD]

So I've been trying to get this preheater done. The hole turned out to be the easy part. The hole saw went right through it, but the trouble I'm really having is with the soldering.

I was able to finally find the liquid flux for stainless/copper, but I still can't get the solder to adhere to the stainless. I tried a low heat/flame approach. It took for ever, but eventually heated enough to melt the solder. A lot of it beads up and rolls off like water on wax paper. Eventually I can puddle up a ring around the hole. After it cooled, however the tinned ring just popped off the stainless.

So I tried a slightly higher flame. It went faster, but got the same result. After it cools, the ring of solder just pops off the stainless when I try to clean it up. I should mention that by the time the solder melts, the flux is long since burnt or gone.

I'm using a solder called silver solder/lead free, but it doesn't have the % breakdown of what's in it. If I go with the Staybrite low-temp silver solder from the welding shop, a 1 lb. spool costs $40.

The guy at the welding shop thinks I should go high temp. and braze it, but that goes against the advice I've got from the folks here. It also means I can't do it b/c I don't have a torch.

Does anybody have any advice for me? Thanks in advance.

[Grade "A"]

I did alot of soldering this year on the pan I made. When I solder copper pipes to my pan I tried lots of methods. What worked best for me was tinning a ring around the stainless first. I did this two ways first I used a old copper soldering iron that worked but was slow, the other was a open flame. First I would scuff the stainless around where I was going to solder with steel-wool then put on some liquid flux for stainless (Harris stay-clean). next I applied heat until it would melt the solder. Some parts the solder would bead off like you talk about, I found that it was because of to much heat (stainless oxidizes when heated and that is why you need the right flex). You can get the solder to stick by adding alittle more flux (1 or 2 drops) on those areas when the stainless is still hot and most of the time the melted solder around the area will flow back in, if not add more solder and heat if needed.

(Big Breath),

Now I took the copper pipe and put it through the tinned hole in the stainless. I did not tin the copper first, instead I would heat the copper and try not get the stainless hot. When the copper was hot enough I added solder to it and it would flow and melt with the solder that was on the stainless. The key was to not get the stainless to hot. I never had the tinned ring pop off but it might be because the stainless surface it to smooth, that is why I scuffed mine up alittle. sorry for the long reply I hope this helps

[SeanD]

I had scuffed/cleaned the stainless with a fine grit sandpaper, but maybe I'm being a little too timid.

I'll go back to the low and slow flame. Did you put the flame right on the flux or did you heat it from the back side of the pan?

Thanks for the help. I appreciate the detail. That's where my mistakes are. I'll give it another whack later today.

[Grade "A"]

I put the heat on the same side I was soldering with a open flame and underside when using the soldering iron. The flux does boil away but you can add more as you are soldering if needed.

[SeanD]

I can't seem to get this. I'm using a flame where the inner blue cone is about a half inch tall and I slowly move it around the opening of the stainless. How long should it take for the stainless to melt the solder?

I'm hitting it with the flame for 20+ minutes with no melting of the solder, but plenty of scorching of the flux. Seems like a long time.

If I increase the flame just a bit, I can get the stainless a little orange and only then do i get the solder to melt, but by then everything is blackened and the solder just runs right off in beads.

If I have used too high a heat on a previous shot is the stainless permanently oxidized? In other words can I keep trying this over and over again?

[RileySugarbush]

Grade "A"'s description is exactly my experience. If you get the stainless orage hot, you are way past too hot. If it takes 20minutes, the flame is way too small. I used Stabrite flux and silver solder. Low to mediam flame, and keep it moving, If you get a spot that beads, drop some flux on it hot and it will be clean enough to fill in. It's tricky, but doable.

[Grade "A"]

I use a small hand torch like all the plumbers use. I had a normal flame but would not let it sit in one place. like RileySugarbush said try moving the flame around alot so you don't get the stainless orange. Once you get the solder to stick in one spot start working your heat in one direction until you have it soldered instead of heating all the stainless at once. Try to clean off the black area with sand paper if you can. I am not sure why the solder is not melting faster, it only takes 10-15 seconds to get the solder to stick to the stainless

[danno]

When I made my finishing pan, I cheated. I bought a threaded spiggot and tightened the hex nut on the back and tightened it down - no leaks. It's an option if you can't get the ss soldered.

[brookledge]

Have you tried a good sized iron? I know that alot of times open flames can be to hot to fast. I've never had expierence soldering stainless but I'm pretty sure the manufactuers use iron and they can go right along.
Especially when doing repair work. Alot of times when the metal is fatiged and thin and you hit it with an open flame the hole will just get bigger and bigger but if you use an iron you can solder it right up. Big soldering irons are not cheap and not many used ones around.
However most are now going to tig welding.
Keith

[SeanD]

Okay, the good news is I got it to work. The normal-sized flame and quick passes over the area did the trick in about 10-15 seconds just like you had said. The stainless accepted the solder pretty solidly. Bizarre stuff, this metallurgy.

The bad news is when I soldered the bushing on, solder dribbled all over the threads (I had tinned it on a previous attempt) rendering it useless for a valve. Wiping it just embedded it into the threads.

That's more than okay, though. I tested the joint and it's rock solid. The technique works even for an idiot like me. Tomorrow I'll reheat the copper bushing, pull it out, and drop in a new clean one. I'm hoping if I do it slow enough the solder on the stainless won't be affected.

Thanks again, Matt and John.

[WF MASON]

If you can heat the threads enough to melt the solder, use a wire hand brush quickly and clean the threads out. If your using a flame , it might be to late though, all the solder will run at once. Wear your leather boots.
Keith is right on , use a big iron.

[3% Solution]

Sean D,
I have been working with a sheetmetal guy making an evaporation enhancement unit and stainless sucks!
Looks very good when done, but it doesn't solder for crap.
From what I was told, it oxyidizes vey quickly and if you don't get it to take the first time it no doubt won't take. Actually you can almost see it oxyidize, turns green where the solder didn't take. Steelwool the heck out of it.
He uses a large iron, cleans it a lot and sometimes that's not enough.
I had a couple of other projects for him, now those will be copper instead of stainless.
Keep at it!!

Dave

[lpakiz]

Hi All,
Instead of regular solder, try using Silver Solder. The flux and alloy are available on EBay or your welding supply shop. Some auto parts store carry welding gas and they also will be able to get the stuff from their gas supplier.
It takes a bit more heat than lead. The metal will have to be a very dull red.
The flux looks like toothpaste. First applied, it is like paste. Then with heat, it turns dry crusty white. More heat and it liquifies. Right after that it will be ready for the alloy to be melted onto the parts. Keep the torch about half on the base metal and half on the wire. After a drop of alloy, you can "dip" the alloy wire into the puddle and the solder will follow the heat anywhere.
Larry

[SeanD]

Here's the finished product. Thanks again to everyone who offered advice. I'll see how it holds up over the season before I try putting a couple in my 2 x 3 pan. Messing around with a cheap steam pan is one thing, but the big pan is something else entirely.

Used steam pan - $20
Flux for stainless - $6.47
Copper bushing - $1.37
Second copper bushing - $1.37
Learning how to solder copper to stainless - Priceless

[OGDENS SUGAR BUSH]

Looks Good From Here

Rich

[WF MASON]

I might of mentioned Sean that copper can be tig welded to stainless with the right welding wire. Brass fittings also. If that was an option.

[Grade "A"]

I would be happy with that. I found out what way worked by first finding 50 ways that didn't work (and lots of 4-letter words). Good job!