90 y.o.hydronic heating system

[Mec]

Hi,

Recently, I have visited an old building with hydronic heating system. However, I have noticed a lots of pipes are rusted and there's leakage. The plumber has shown us a section of clogged pipe. In addition, I saw spots of rust on the radiator, the landlord told me that the radiator also leaked. Can somebody tell me how come this kind of system can rust, it's a closed system?

Thanks!

 

[Matt30]

Its likely full of black iron pipes.

While it is a closed system, you have to make up lost water from time to time. Weather you lose it thru a leak, or evaporation the system has to replenish itself. Your make up water, is now fresh water which has oxygen. Black iron/cast iron/some steel doesnt like oxygen. So if you are having a constant supply of fresh water introducing oxygen to the system all the time it will begin to attack your pipes and boiler.

If its a condensing boiler, that could be opening up a whole new can of worms. But for now ill just assume it isnt.

 

[Mec]

Thank you!

 

[Matt30]

You're welcome