Copper feed and dry returns directly to black pipe

Koan

Hi - trying to help a very nice new next door neighbor. Two pipe vapor Hoffman steam system just like mine except they have a much newer boiler. The wet return header next to the boiler is all large copper - never seen that before but I believe @Steamhead said that may be a good idea to reduce build up in that area (which I have been fighting).

My concern is the GC had a plumber replace some supply and dry return pipe with copper. The copper is soldered to a male copper adapter then threaded right into the existing black pipe. I saw this and brought up the possibility of electro-galvanization possibly eating away the steel pipe at the junction. I have seen this (in our house!) in water feeds between copper and galvanized pipe and I assume it is a concern with steam piping as well but I am unsure. I suggested at the very least using brass connectors between the copper and steel.

The neighbor asked the general contractor who kind of just bullied them and said two plumbers that looked at this were master mechanics. The GC said the plumbers know more about this, "than your neighbor who probably just Googled it." When the neighbor asked the plumbers directly, neither were familiar with galvanization. At least one of them said he would look into it. How can a master plumber not know about this? Moreover, why is the GC deflecting rather than explaining with facts?

The pipes will run vertically through a sealed wall then horizontally in a sealed ceiling.

So my friends, please help me to help my new neighbor:

1) Is it acceptable to use copper feeds and dry returns at all?
2) If not, why specifically (thermal expansion, solder joints fail, issue with dissimilar metals)
3) Why is it acceptable to use larger copper at the wet boiler return header?
4) Is it somehow acceptable to join copper to steel in this case because it is a steam supply and dry return?
5) Or, should there be some more noble metal (brass) as a junction?
6) I assume a dielectric union is not made to tolerate the temperature of steam heat - correct?

I really want to help and not create needless concern.
thank you all for your input.

Paul S_3

Copper should not be used in a steam system.....for the exact reason you stated above....when i go from steal to copper i use brass between in hot water heating systems .... i never use those dielectric unions ive seen way too many clog up.....i guess they used a larger copper wet return header so its harder to clog up?.....maybe someone else can chime in..... you be fighting a losing battle with the contractors and plumbers are there any problems now With the system? Your neighbor should hire a professional for this or let you work on there system since you worked on your own.....99% when a GC uses a specific plumber, hvac contractor etc is because there cheap and hardly do good work....have your neighbor hire seperately ....

Koan

@Paul S thank you very much for the reply, but to be clear when I explain it to my neighbor, why is copper not to be used in the steam system? Is it for all the reasons I stated or because of just thermal expansion or because of dissimilar joints or all the above??

Paul S_3

Both

Jamie Hall

A few points -- first off, @Paul S is quite right; ideally copper shouldn't be used in steam carrying lines. Further, ideally there should be a brass junction if it is connected to black iron.

However... copper is perfectly fine below the water line -- a wet return, for instance.

The problem with copper in steam lines is primarily expansion, particularly if the junction between copper and black iron is where water can't lie in it. Therefore, since what you are worried about is expansion, take a look at the piping arrangement and see if the piping is arranged so that expansion can take place. Thus you don't want a copper header between two risers from a boiler. But a copper riser or runout to a radiator will be OK. Not great, but OK. What you may find as a problem is expansion noise when the system heats up or cools down, but that can be handled by making sure that there is room for the pipe to move. In general -- if the copper line can move at one end, you are probably going to be alright.

KC_Jones

So they are master mechanics, are they master steam fitters? Steam is a specialty and a majority of plumbers don't have a clue. Don't even know about galvanic corrosion, yeah I learned about that when my age was in single digits. Sounds like your neighbor has a bunch of hacks working on their house. If you are within the service area of @Steamhead your neighbor should call him and only allow him to work on their system and never look back. It's their house and if the GC is "bullying" them I would probably fire the GC too. Of course I am fairly black and white about things.

The expansion and contraction of going from ambient to steam hot and back again. That works the joints in the copper and can break them over time and then it leaks. The threaded black pipe will allow for some movement (with proper swing joints) and continue to function without leaks. In all honesty the corrosion would be the least of my worries.

Have they sloped everything properly? No water traps in the way they ran pipes? Have they sized them correctly? Running in copper indicates lack of knowledge, what other details are they not knowledgeable about? Have they used best practices to ensure those pipes in the ceiling won't make expansion noises? I am guessing they are re routing pipes due to remodeling?

Ask your neighbor if they like gambling? Seal up all the walls complete the remodel and then all the pipes are banging, or leaking or the house doesn't heat properly. What will the GC and the master mechanics do then?

Tell them to call Steamhead.

Koan

I'm hoping @Steamhead will weigh in on this. He knows where my house is as he has been there and helped us out tremendously. Their house is right next door, attached by a party wall to ours.

Steamhead

What KC, Jamie and Paul S said. That piping should be black threaded steel. And thanks for the recommendation!

New England SteamWorks

There is also this: copper is easy. All hand tools. Cut, solder, set. Black pipe requires an inventory of fittings, nipples, heavy pipe, and a big heavy threader. Oh, -and math.

Let's see:

A. Copper easy
B. Black pipe hard

Tough decision for them I bet.

Koan

@Steamhead , @Paul S , @Jamie Hall , @RI_SteamWorks, @KC_Jones.

Thank you all very much. I'm going to take this whole conversation and share it. You have all been very helpful and your input is greatly appreciated. You are helping a nice family in doing this.