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How often to flush radiant loops ?

mootsmoots Posts: 18Member
Hi Folks:

I have a Burnham boiler with a combination of copper and mostly older galvanized ? piping for water based heat. Every few years in the past I have flushed the lines out which resulted in quite a bit of brown/dark water per zone I assume from aging piping and aging baseboard radiators.

How often or should I even do this for maintenance ?

Maybe every 3 years ?




  • GilmorrieGilmorrie Posts: 98Member
    edited October 2018
    Do not flush routinely. Every time you flush, you wind up injecting air that is entrained or dissolved in the fresh water, which causes corrosion. The brown water is normal and harmless - it quickly returns after flushing.

    Hydronic systems normally use black steel pipe, not galvanized. If yours is galvanized, that is fine though.
  • hot_rodhot_rod Posts: 11,252Member
    As little as possible. Put in good water with some hydronic conditioner and leave it be.
    Every time you add new water you are adding more O2 and minerals to the system and making conditions worse.

    The water will always have some color to it when you open a drain, that is not a problem.

    If you have some of the early radiant tube like Heatway Entran 2, or grey polybutylene, you need to keep a chemical regiment as those tubes allow O2 into the system. And/ or use all non ferrous components in non barrier tube systems.

    Now a water heater is a different animal, flush those occasionally to help keep the sediment out.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
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