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adding additive to hydronic system?

ron Member Posts: 339
I have to replace some shutoff valves so I will be draining the system. I am interested in using a corrosion inhibitor additive. How does one add something like that to a hydronic system? And what's a good one that I should use?

setup: WM WGO-3 oil boiler with WM indirect tank, one circulator doing 2 zones having taco zone valves, and a 2nd circulator for the loop between the indirect and the boiler.


  • flat_twin
    flat_twin Member Posts: 335
    Weil McLain included a tube of Sentinel X-100 and a test kit with our Eco boiler. I used a caulk gun, shoved the tip of the tube into a short cut off piece of washing machine hose and threaded it to the low point drain of the boiler. Might be a good idea to test your fill water so you know what you're starting with regarding ph, water hardness and chlorides.
  • ron
    ron Member Posts: 339
    the fill water is city water (which is good to begin with) after passing thru an aquapure AP904 filter.

    I might re-relocate my expansion tank in addition to replacing zone valves and shut off valves on the return side prior to boiler. looking for piping ideas to make adding any cleaner/additive to the system easy