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Cast Iron Radiator Cleaning

Hello, I am restoring an old farm house and I am keeping the cast iron heaters. I am wondering what I should put in the boiler water to clean inside the cast iron radiators / heat lines.


  • Jamie Hall
    Jamie Hall Member Posts: 21,535
    Steam or hot water? If it's steam, there's no need to do anything at all for the radiators and the steam lines. Wet returns might need to be flushed, but that's just a matter of figuring out how to run water through them. If it's hot water, there are a number of cleaners which can be used -- if needed.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • RidgeReaper56
    RidgeReaper56 Member Posts: 9
    It's hot water
  • hot_rod
    hot_rod Member Posts: 19,877
    You could install and run a hydronic cleaner, just a strong detergent really.

    Then flush with a good flow rate to move out and rust and dirt particles. It is tough to get all the corrosion particles cleaned out of old rads like that.

    Best not to over pump them and strip up the crud that will get into circulators, boilers and control valves.

    I'd also add a good dirt separator with a magnetic function to help keep any crud that breaks loose out of the components.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Gilmorrie
    Gilmorrie Member Posts: 180
    A hot water boiler shouldn't need to be flushed. By flushing you add a lot of water with dissolved or entrained oxygen - which leads to corrosion. Make sure that you have an operating air elimination device.
  • flat_twin
    flat_twin Member Posts: 340
    Glad to hear you're keeping those radiators. Seems like many remodeling jobs toss the cast iron rads in favor of forced air. If you replace the boiler down the road, thats the time to flush the heating system and add a corrosion inhibitor.
  • mikeg2015
    mikeg2015 Member Posts: 1,194
    A little crud sitting in the bottom the radiator would have a negligible impact on operation anyway.

    Use a good boiler treatment and follow the instructions. They may include a single flushing or just draining off crud from the return.

    A mentioned, a good dirt separator is a must have item, especially if a high efficiency boiler is used.

    An never drain a system once filled except for repairs. Keep it under pressure and fix any leaks even if minor.
  • RidgeReaper56
    RidgeReaper56 Member Posts: 9
    Thank you everyone for your input