Cast iron radiators and water treatment concerns

[goosegunner]

I talked to Precision chemicals today about cleaning the old cast iron radiators if I buy them. He said it would be asking for problems if I added them to my system due to all the rust and crap I could introduce to my expensive system.

I asked about using a plate exchanger between and he said that would be good to isolate the two.

After thinking about using them in my garage and shed maybe that would be better anyway because I could use glycol in them in case I decide not to heat for a while.

What does a plate exchanger and glycol due to efficiency of cast iron radiators?

gg

 

[ewdudley]

I talked to Precision chemicals today about cleaning the old cast iron radiators if I buy them. He said it would be asking for problems if I added them to my system due to all the rust and crap I could introduce to my expensive system.

Sounds like afraidium contamination to me. After the radiators have been flushed, rinsed with acid, and flushed clean, just how many pounds of rust could possibly remain ready to contaminate the system? And crap, what crap? Are they full of mouse nests and hornet hives?

 

[goosegunner]

No I when I say crap I just meant rust and scale debris. He said because cast is so pourous it is really hard to clean.

Does the acid flush do a good job cleaning the metal?

EW as long as I have your attention what is your feeling on copper to black iron to steel tank. I get confused on all the different opinions on metal contact.

gg

 

[ewdudley]

No I when I say crap I just meant rust and scale debris. He said because cast is so pourous it is really hard to clean.

Chinese cast iron and General Motors cast aluminum can get pretty porous, but if radiators with shells two or three sixteenths of and inch thick can hold water for a century or more it's fair to assume the inside of the radiators are no more porous than their smooth exteriors.

Does the acid flush do a good job cleaning the metal?

Good enough I guess, when the muscle car frames come back from the acid dip shop they're ready for primer. All you need is to get the loose rust out. Inside a closed hydronic system anything left would be inert soon enough.

EW as long as I have your attention what is your feeling on copper to black iron to steel tank. I get confused on all the different opinions on metal contact.

By the book you need brass in between, but if the outside is dry and the inside is free of oxygen and/or an effective electrolyte then going directly from copper to steel is done all the time in closed hydronic systems with no ill effects. I had to rework some plumbing when I replaced a 37 year old oil boiler in our house that had some direct copper to steel fittings here and there and I could find no evidence of any problems. However I can't sit down and tell you here's the ions, there's the metals, and this is exactly why there won't be a problem.