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Brand new hydronic system. Water brown/black

jeff121 Member Posts: 13
edited December 2017 in THE MAIN WALL
Hey guys. Just fired up my boiler for the 1st time. Litterally brand new everything, top to bottom. Turned on 1 zone to make sure everything worked, and it did. But after 1 hr of running, i can see the pex lines turning brown/black. Should i flush the system again? Something else i should look into?

Its a buderus g115/ws4 with a riello bf3 direct vent


  • hot_rod
    hot_rod Member Posts: 22,467
    Did you run a cleaner when you first filled? The cleaners will strip out flux, oil, pipe dope, etc. Then flush and refill with good water.

    The boiler installation manual probably has a water spec, TDS, Ph, maybe more numbers to check.

    You will always get some color in the water as the O2 in the fill will oxidize any ferrous components. Usually a grey or light red color after a few days.

    A hydronic conditioner will also assure a good fluid quality after you clean flush, fill, watch for leaks, then add a conditioner.

    Rhomar, Fernox, Sentential are a few good brands. Get a start up kit that includes an arose can of cleaner, and conditioner to squirt into a drain valve.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • jeff121
    jeff121 Member Posts: 13
    no i did not run a cleaner. I did let it circulate, flush. heated up, flush. I got home today and let it circulate with the return shut while flushing...the water is crystal clear. I will pick up some chemical flush this weekend. Does the pex turn brown/ black for any reason other then minerals in the water? I think the high temp i saw was 184*. i know the pex is supposed to be good to 200-210*F
  • kcopp
    kcopp Member Posts: 4,448
    The pex is not breaking down. Its just a film on the inside. Copper tubing would do the same...just cant see it.