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Drain, flush, refill annually?

Bucky Member Posts: 47
Hey all, me being a glutton for punishment and all, I was reading the comments in a radiator problem question posted on facebook. One of the commentors stated that "you should drain and flush your radiators every year". And it's picked up a bunch of "likes" too.

This is something I'd never heard of- in fact, if pressed, I would say to NOT drain and refill unless there's a specific reason- don't want to introduce more air into the system unnecessarily. I own and have read most of Dan's hydronics books, and I don't recall any recommendations like that in any of those (although it has been a while!)

So with your typical old iron radiator system, is there any interval for drain/flush/fill that I should undertake? Thanks!


  • PC7060
    PC7060 Member Posts: 1,156
    Steam or hot water. Definitely no for hot water.  Not an expert but expect same answer for steam systems. 
  • Bucky
    Bucky Member Posts: 47
    Hot water, I should've clarified!
  • Jamie Hall
    Jamie Hall Member Posts: 23,270
    I can't see any reason for a specific drain and flush -- of the entire system -- unless it is necessary to replace the water treatment or the treatment, if any, was poor and you need to flush that out.

    Not the radiators spcifically.

    And certainly not for steam.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • bucksnort
    bucksnort Member Posts: 167
    I think in 34 years I emptied my system once. And that was because I took out an upstairs radiator. Still on the original Taco 007 too.
  • hot_rod
    hot_rod Member Posts: 22,100
    Every time you add fresh water you add oxygen and whatever minerals are in the water. Fill it once with good quality water and let it run.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream