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cleaning and old CI rad for HW system

GW Member Posts: 4,693
Thanks for the help on the last thread, I think I'm going to just tap the other side and not mess with the slotted plug.

I would like to clean out this old rad and make it spanky fresh so my new wall hung Viessmann doesn't object (this will be the only "old" part of the entire new heating system).

Is there a magic formula for TSP or should I go after some other solution?

Thanks for the help!

Gary Wilson
Wilson Services, Inc
Northampton, MA


  • Brad White
    Brad White Member Posts: 2,398

    Gary, do you mean what concentration to use or to use a different chemical entirely?

    I would take about a cup of TSP per gallon in the hottest water you can get from the tap in order to dissolve it. If it precipitates out, the solution is saturated so back off from that. Hook up a cheap circulator with hoses in and out of the radiator and let it run overnight. The first cleaning will take out most of it.

    Drain and repeat until the water runs clear and does not have that "slippery" feel to it.

    A large wye strainer with some rare earth magnets can harvest stray iron continuously upstream of the Vito, for less money than my Neptune filter feeder.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
  • Ken_40
    Ken_40 Member Posts: 1,320
    I would...

    Hook upo the entire system and clean it all - with TSP. There's the boiler, the old rad, and the rest of the system. Cutting oils, flux, pipe dope, rust, scale, etc. are present. Why just focus on the old rad when the rest is also suspect/contaminated?

    About one cup per 100,000BTU's is typical. Pump it in somehow, remove the air (bleed?) heat for 1/2 an hour while circulating and dump it all - rinsing well. All the "funk" will be out, and only fresh clean water will be left. Trace amounts of TSP are a good thing, because the pH of TSP is alkaline, it acts as a mild rust/corrosion inhibitor.

    BTW, nice day at Ruthies!

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