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convert open system to closed system

I installed a diy open radiant system in my new house 5 years ago, slab on grade with in floor heat.  I am not happy with the way it heats . In redoing my heat source and some of the piping i want to convert  the system to a closed system where my newly bought water heater, AO smith cyclone xi bth-150 95% efficient unit heats my floor water via a heat exchanger and still supplies my domestic hot water. After reading about diseases when you have an open system where potable and radiant water are mixed i figure this is safer  for my family.My problem is that when i was sold my pex tubing, it was designed for an open system and the tubing doesn't have a o2 barrier. What should i do to prevent oxidation in my pumps, valves, etc. i haven't bought the heat exchanger yet. should it be of a special material to resist oxidation. its hard to get help from anyone local when you did'nt buy the system or have it installed by them.

thank you for any help 


  • Paul Pollets
    Paul Pollets Member Posts: 3,656
    edited September 2009

    A good solution would be to install the Taco X-Block,a module which has a built in flat plate HX, pumps and control. It will separate the non-barrier tubing from the heat source. You'll need to add an expansion tank, relief valve, tridicator gauge and feed source, per the manufacturers' instructions.  Using a water heater is not the best idea in hydronic heating. Try a mod-con boiler and an indirect tank for the upgrade...;
  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    closed side non-ferrous?

    I think the X-block has a cast iron pump on the system side? I might be wrong, but I think it's only non ferrous on the expected open side.

    If I am right though, you can do what the xblock does with heat exchange, and non ferrous pumps on both sides.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
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