Best Solution for Connecting Copper to Iron Boiler

bassman92 · March 8

The picture above is the return line on my boiler, which obviously needs to be replaced.

It’s currently copper ⇒ iron elbow and nipple ⇒ boiler.

Is there a better way to connect this to prevent galvanic corrosion?

As far as I understand, here are my options:

Replace with the same. Replace again when it inevitably corrodes.
Use brass or bronze nipple and elbow. (Will this cause my boiler to corrode faster?)
Use a dielectric union. (But then I need a ground jumper, right? That doesn’t defeat the purpose of the dielectric union?)

Which option is best? Or is there another solution that I’m missing?

mattmia2 · March 8

just use a copper adapter. it is all crusty because it is leaking, not because it is iron to copper.

if it wasn't an installation issue then you might want to be concerned about the system getting a lot of makeup water or possibly an issue with the electrical system.

the leak is above your picture somewhere, wherever that crusty trail starts.

pecmsg · March 8

does this system have glycol in it?

bassman92 · March 8

https://forum.heatinghelp.com/discussion/comment/1847321#Comment_1847321

There is an a pinhole above it, yes.

You think copper to iron is a non-issue then?

Hopefully it’s just that the joint above it wasn’t sweated correctly

mattmia2 · March 8

It was either a bad solder joint or some issue with the water quality in the system. If it has glycol in it, that needs to be maintained or it will become corrosive. that is why @pecmsg asked. Occasionally the potable water that was used to fill the system is very aggressive. If there are small leaks and a lot of fresh water being added to the system, that will cause corrosion. In a closed hot water heating system with reasonable quality fluid connecting copper and steel directly isn't an issue.

Mad Dog_2 · March 8

Boiler? Round? That's a water heater or storage tank...Mad Dog

mattmia2 · March 9

https://forum.heatinghelp.com/discussion/comment/1847358#Comment_1847358

i think that is just the shadow of the mc

delcrossv · March 9

Not as much of an issue with a boiler, but code here for potable is to use a brass transition fitting between copper and iron pipe. Wouldn't hurt in any event.

Water heaters always need dielectric unions.

PC7060 · March 9

https://forum.heatinghelp.com/discussion/comment/1847358#Comment_1847358

Believe HTP Pioneers were round tanks similar to potable water heaters.

Intplm. · March 9

Experience has proven to me that a brass fitting or valve between copper and black pipe is a great transition method. It causes the least amount of issues.

@bassman92 You can also use a dielectric nipple as a transition fitting.

bassman92 · March 9

https://forum.heatinghelp.com/discussion/comment/1847323#Comment_1847323

https://forum.heatinghelp.com/discussion/comment/1847333#Comment_1847333

The system has never had glycol in it as far as I know. It does use well water, so it's possible there is a water quality issue. Besides the one pictured, I don't know of any leaks, although the area below the pressure release valve is sometimes damp—should probably change that out as well.

bassman92 · March 9

Correct, it is a boiler, definitely rectangle, not round.

pecmsg · March 9

can you post a pic from further back?

bassman92 · March 9

This makes sense.

Think I will go with an iron elbow out of the boiler and use this for my transition to copper: https://www.supplyhouse.com/Viega-79260-1-1-4-ProPress-x-Male-Bronze-Adapter-Lead-Free

mattmia2 · March 9

if the relief is dripping it is probably an issue with the expansion tank although the relief valve should be replaced every few years anyhow.

if the expansion tank is waterlogged and causing the relief valve to blow off when the system is hot that will bring fresh water in to the system and cause corrosion.

GroundUp · March 9

Galvanic corrosion and electrolysis are mostly mythical when it comes to closed loop hydronic systems. The corrosion pictured is due to a leak, not dissimilar metals. If it makes you feel better to use a brass elbow or valve, go for it but it's not necessary in a leak free system. Absolutely do NOT use dielectric unions- they cause 100x more issues than they solve.