Connecting Steel and Copper Pipes: Central Heating Boiler Replacement & Corrosion Risks

Hello.
I intend to replace only the central heating boiler and the installer informed me about the need to replace the entire installation in the building, because according to him, if the steel pipes in the central heating system are connected with copper pipes, the steel pipes will corrode faster.
Is it true?

Yes, but: It will corrode the steel pipe where it connects to the copper one. If the connection is made with a piece of plastic pipe, for example, then it will not.
If every steel in the installation combined with copper corroded, then the furnace would also have to be copper.

You can also connect a steel boiler with a copper installation using a union.

There is a bit of truth in this. Small electric cells are created, where theoretically corrosion develops faster. It supports high-pressure devices, where various brass or copper elements are used. more often they corrode and need to be replaced, although special chemicals are used to maintain the proper pH, so that corrosion does not occur. flexible connections have been installed for years and at the moment there are no damages due to this. All heat exchange coolers are made of copper and silver welded and then connected with metal elbows, then stainless steel flexible connection, iron pipes and there is no corrosion at all. The most common elements where corrosion occurs are the elements return water vapor. Personally, I would not replace the entire installation if it is made of copper, because it will certainly serve longer than iron pipes.

Hello
while I plan to replace the steel pipe installations with pex / al / pex ... I have copper led out of the boiler and now how to connect plastic with copper?
Regards

There are special threaded connections to connect the plastic with other elements. You also need to take into account the temperature at which it will work and what pressure the system will have. Will it be a water or steam system so as not to tear the plastic connections.

Each PEX system has threaded fittings. Restrictions only apply to temperature and pressure, but that's only for PEX pipe

And in pex-al-a fittings, special plastic rings are used to prevent electrochemical corrosion between the aluminum core and the brass fitting.
And there are so-called corrosion inhibitors that reduce the impact of different materials on each other in the installation.
Regards

Before the holes fall out, there will be such a scale or sediment (black) that the efficiency of the system drops at a rapid pace. I know from personal experience. Physicists or chemists even trumpet about this and they are right. Fe and CU and the appropriate PH of water always = electrochemical corrosion. no brass or plastic "inserts" can stop the process. Only PROPER water treatment prolongs the life of the installation (without loss of efficiency).
Then we have posts like,..help mega-gas bills.

On a micro scale (the building you are right - first of all, do not mix), but on a macro scale (water supply network), you have everything tangled and somehow it works.

It works because in the water supply system copper is the last link, and the water "doesn't go around".

Yes, but from steel to copper! Never the other way around!!

That's what I wrote.

hehe the overlay!

From the point of view of electrochemistry, it makes no difference whether copper is on the right or on the left. Cell current copper electrolyte (water) steel always flows in one direction, no matter if the water is circulating or standing. In the home installation, you have copper pipes and steel or aluminum radiators. Both have a lower electrochemical potential than copper, so it should corrode most at the point of contact.

Hello!
Sorry to butt in, but what corrosion time are we talking about: 5 years, 10, or more, and what factors affect the rate of corrosion. If we create a cell, we can also short-circuit it (I don't know - with a jumper, a counter-cell, or an electrode - as in electric boilers.

Hi!

I do not know how they can be shorted, but one phenomenon I have been observing for years, i.e. siltation of heat exchangers (all) and a serious decrease in efficiency.
I wrote butter butter, but I have no words to explain it to dull hardened brains!
I wrote about it a few posts ago!!!
I am no physicist or chemist, just an "observer" for years after what I read in professional magazines, and unfortunately they are right! Only that everything depends on many factors, how is this evil perceived? I would have to write for a long time.
In short, I will say that the wrong pH of the water + economically calculated radiator power = problem!!! Oversized power and adjacent to the duplex wall = approx. For many years my attention has been focused on, among others, on this, and I already know it. But I'm about to meet a different opinion from the tabloid press or I don't know what. But please, I'll read it.

Here, we all consider joining steel and copper pipes, and we all assemble metal radiators for copper installations.
WHAT'S GOING ON ?

Metal radiators for copper installations... as if copper wasn't a metal. I have had such a combined installation at home for 15 years. There are no problems.

Please do a simple experiment. Put two copper and steel wires in a potato, apple or lemon and measure the voltage with a millivoltmeter. You can make several such cells and connect them in series to power, for example, a watch!
Nothing seems to happen in the installation, but just drain some water and wait for it to settle. Then you can see nothing.
As I wrote, everything depends ... on the ph of the water, especially! Therefore, using a corrosion inhibitor, you can easily connect steel radiators with a copper installation.
I also know installations where nothing happens (water intake from the Brda River) and also those where after two or three years the exchangers in the boilers are covered with black mud and stone (deep water intake from the Gdańsk Forest)
If everything is so rosy, why has KAPEC been treating water for years?

Water is treated rather because of hardness, not galvanic cells ... Treated water also has a reaction (unless someone purifies the water osmotically). In order for it not to be an electrolyte (although it is weak), you would have to pour distilled ...

The main reason for water treatment is scale. After a few years, it can cause cracking of the boiler block. As it happened recently in one of the boiler rooms. After this incident, they remembered to treat the water...

Sorry winetu, but you can write what you want! You won't convince me so easily. Read books to children, not to me. Forgive me, you need to work a bit and observe, and then let's share the experience.
I read a bit on various forums and there I also found what I observe myself. So don't talk about matters in which you have no experience.
MB-1 conditioner, do you know it? If not, read what it is for and what it does with water for CO purposes. If you find other products of this company, then also read exactly what they do, and then write on the forum where hundreds of people are reading you can enter in error.

What did I say that wasn't true? Specifically, please.

Quote:

MB-1 conditioner, do you know it? If not, read what it is for and what it does with water for CO purposes. If you find other products of this company, then also read exactly what they do

I'm sorry but maybe we'll start with this, and then a discussion supported by many years of experience, ok? And no offense please.

I read it and I still don't know where I made such a mistake. The preparation slows down corrosion but does not eliminate it. You say that solves the problem. I believe. But I do not believe that the link does not form then. I understand that experience is very important, but you can't forget about theory.

So I say what I know! And I have had a lot of tests for 25 years. A gaffe is in the first sentence. Not that I am not mistaken, but I have an example at my neighbor's side, whose late father made a new central heating and hot water system 12 years ago because they had tiles and an electric boiler. Installation in Cu, steel radiators and a Beretta II-functional boiler. Who do you think maintains it to this day? Then my father listened to his son for the first time and asked to install MB-1 in proportion to the max as stated in the manual Until today, in the heater, I have not found anything but polished metal (CU) inside from the water entry side!!! I took it for HCL because I did not believe it, but unfortunately, or fortunately, no scale!

I most definitely believe! We only wrote about something else because not about stone but about electrochemical corrosion, but there is no point in discussing it any longer. I learned a lot from this conversation. But wouldn't installing a reverse osmosis system give the same effect? I ask out of curiosity.

km88 wrote:

I most definitely believe! We only wrote about something else because not about stone but about electrochemical corrosion, but there is no point in discussing it any longer. I learned a lot from this conversation. But wouldn't installing a reverse osmosis system give the same effect? I ask out of curiosity.

I made such installations copper combined with ordinary pipes eight / ten years ago and nothing happens, the sea is true about the negative impact of copper on steel, but I don't have such unpleasant experiences. Regards.

It has to work and it has to break. That's what life is all about. There are no eternal things.

Gentlemen, you say that nothing bad is happening. And what is the definition of "bad" and in what heating system. Some time ago I replaced a 45-year-old installation that worked "properly" until the very end. After replacing the pipes and radiators, the client was surprised that it gets warm so quickly in the apartment and uses less gas per month!
I suspect that the plumber who performed it would also argue that his work has been working for 45 years and nothing bad is happening. Did I make myself clear?