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Clean rust out of Radiant Tubing?

Having done this four times now, and losing the eight paragraph posting each time, here is the short version!

Have a 16-year-old radiant system using red 3/8" Bio-Flex non-barrier tubing in a staple-up application. Original system, without a heat exchanger, went through two stainless boilers in the first four years and is now running a larger cast iron boiler with a heat exchanger installed. Despite the separate system, I continue to get rust out of the system during purgings, and the circulators continue to require annual cleanings to remove the almost solid black deposits completely filling them. I am currently having problems heating my LR/DR zone, which dried out completely in 2006 when the manifold failed (sparking the heat exchanger and several other system improvements), above 55-60 degrees despite the circulator running full time (boiler does cycle so is not undersized). I believe that the drying may have plugged up much of the tubing (water still flows) and have not been able to blow it out using 90 psi water. Is there any other way to clean the rust out of the system once and for all? Any chemical means can not hurt the tubing. Any help would be appreciated. Bill


  • Paul Pollets
    Paul Pollets Member Posts: 3,617
    edited October 2009
    Non Barrier system

    If you have an iron pump on the non-barrier system side, rather than a stainless or bronze pump, that could be a problem.  Cleaning a system may not be easy.

    I use Rhomar chemicals, Hydro-Solve to clean....ProTek added after the sytem is cleaned. Check out their website...

  • Bill_In_CT
    Bill_In_CT Member Posts: 2
    Cleaning rust out of radiant tubing

    Paul, thanks for the information, and I have confirmed that these products are sold locally. I am sure it will take a while to get it all out, but at least I have something more effective than system heat and water flow to help rid the system of scale, etc. As far as actually adding these fluids to the system, what do you recommend? I remember the installer adding "tubing conditioner" with what he called a "bucket pump." Looked much like a manual tire pump, open at the bottom for intake, and with a hose having a standard male hose coupling designed to go on a boiler drain valve.

    I have just replaced one of the four cast iron circulators with a bronze pump, and will begin to replace the others as I can (currently out of work and understandably trying to keep my expenditures low). The only other items on the system side that are not copper, brass, or bronze are the stainless steel plate heat exchanger, and the expansion tank. As the threaded areas of the expansion tank seems to rot out every year or so (with spectacular results!), I will look for one with an epoxy or other coating to kill the raw steel edge. Thanks again for your reply, Bill
  • Paul Pollets
    Paul Pollets Member Posts: 3,617
    edited October 2009
    Non-Barrier protection

    The steel expansion tank needs to be changed to a potable expansion Amtrol ST-12 or equal. Sometimes, we use 2 tanks, depending upon the size of system.

    Cleaning the system requires several types of pumps, either a Silver King force pump or a condensate cleaning acid pump.  Both are expensive and require knowledge of how to clear the stubborn debris.(hot fluid works best) and patience.  We use  a compressor to blow the debris out of the loops, after chemical treatment has softened the crud, in worst case scenarios. 
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