I have a question concerning a repair job I'm doing to my boiler lines. I have hot water baseboard heating in my house and I have removed a section of baseboard element to replace with a smaller kickspace heater. The main loops in the heating system are constructed of steel tubing (I assume galvanized tubing) that is the same outside diameter as 1/2" copper pipe. The elements themselves have copper piping and have been sweated to the steel lines throughout the house. My question is, what type of solder and flux do I use to join the steel piping to copper? Installation instructions for the kickspace heater recommend using 95-5 solder. Is 95-5 a good choice and is there a specific solder to use for this job?

Thank-you in advance.

Mike

 

I always thought that steel and copper weren't supposed to go together like that. If I were going to connect them, I'd use a Shark-Bite coupling.

 

I thought the same thing about steel/copper but all the steel/coopper joints in my hydronic system are in perfect condition. Maybee because the solder separates the metals from direct contact? Maybee because of low oxygen levels in the hot water? Not sure.

Shark Bite is an interesting idea. I checked their web site and they are approved for hydronic systems but I wonder how those teeth would "bite" into the steel pipe.

 

I'm hoping a Pro weighs in...but I've never heard of soldering or brazing any steel to copper anything....

I'll be watching to see some expert answers.

 

I called Shark_Bite and they said NO GOOD. So forget that idea. I also asked him what solder he would recommend and he said that he had never heard of joing the two. I haven't either.

The idea of not having two different types of metals together is because of a chemical reaction between the two. It's well known in the plumbing world. What would it take to change everything to copper?

 

Mike, not that we don't believe ya... but can you post some pics of at least one of the joints? I think you CAN braze the two, but would you WANT to?

Is the filling silver in color? or yellowy brassy color?

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Soldering steel/iron isn't easy. Need to use a flux such as Kapp Comet, which isn't the nicest stuff around. Along with an high level of antimony with some silver in the solder for best results.

_Usually in plumbing_, the iron pipe is threaded, then a threaded copper fitting screwed onto it (with sealant). This allows other copper to be sweat to the copper fitting. Or even better, sweat the copper to the fitting, then thread onto the iron pipe.

Al.

 

This is a picture of the water return lines where they join with the control valves. The silver pipes coming into the valves are steel. ( I checked with a magnet). The steel tubing is the same dimensionally as 1/2" copper tube andthe whole house is run with this tubing and soldered into copper at the heating elements. The solder is silver in appearance. Now I did try some test solders yesterday on galvanized steel fittings. The solder adhered nicely using 95/5 solder which is 95% tin and 5% antimony. I used Oatey tinning flux too. It seems to work on my test sample but I would love to have some backup on this one. I would appreciate any more thoughts or ideas.

Mike

 

Maybe I'm older than I thought, but in my tattered old memory, you don't want to be heating up galvanized anything. Toxic fumes. If I'm wrong, I'll be out behind the wood shed waiting for my punishment .

Bud

 

[QUOTE=hooknem;1529560]... Now I did try some test solders yesterday on galvanized steel fittings...

Mike

Ahh, I missed the 'probably galvanized' in your original post. Being zinc plated is probably what makes the difference. I've never tried soldering to galvanized steel.

Al.

 

While I am in the HVAC field I am NOT a plumber.. is the galvinized pipe not meeting a BRASS valve in your pics? and not copper? edit.. let me answer that...
lol sorry...
The 95-5 would be great for copper to copper.. which is what the manf. probably recommends them to be brazed to.

Harris 45% Silver Solder for copper to brass, copper to steel, copper to stainless. With white paste flux.

You CAN solder galvanized, however, and it works quite well. It is perfectly safe if you're using a soldering iron, which doesn't heat up the zinc enough to be dangerous. You DO
NOT want to use a flame to solder it, however, as that will definitely vaporize the zinc coating.

and I am not sure where you are but here....

"Galvanized materials cannot legally connect to copper unless a dielectric union is used to avoid electrolysis."

all that said.. I would stub the copper to the dielectric union and then join the Galvanized pipe.

 

If the pipes above the valves you show in the picture are the "galvanized", they are not galvanized steel but rather tin coated copper. Such pipe used to be very commonly used for gas piping.
Another thing which makes me think you are not dealing with galvanized steel is the size. Galvanized steel & copper are two different sizes.

 

But Grady...he said a magnet sticks?

 

Oops. Didn't see that but something in the back of this feeble only mind tells me that pipe is attracted to a magnet. My iniitial thought of tin coated copper may not be correct.

 

I own some pretty big soldering irons... but I seriously doubt that even the biggest one I have is big enough to solder those pipes, and it almost takes two hands to pick it up!

Yeah, heed the warnings about vaporizing the galvanized... one of the first things they teach in welding school!

I believe the reason they are recommending that particular solder is for the lower melting point... they don't want you overheating the connection points to the kicker.

No... that's not true... 95/5 has about the HIGHEST melting point... hmmmmmm.

 

i have galvanized pipes in my heating system half of which have brass elbows with a plug in the curve of the elbow, but the rest are sodered directly to the copper baseboards, not right i know but it can be done. i will be replacing mine with pex and sweating a union onto the copper. whole neighborhood had galvanized, 50's ranhc's, a lot had problems of pipes rotting from inside out.