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Non-ferrous components for closed loop hydronic systems

davidd Member Posts: 84

In looking over my current boiler closed loop and thinking to the future, when I intend to add on another closed loop/heat exchanger for under floor heat, I'm wondering about reducing the amount of iron containing components. I doubt I'll be able to get rid of every bit of it, but the more I reduce it, the longer my water can maintain its proper chemistry. I'm not suggesting to not treat the water with an inhibitor.

Given the above, I'm asking for references to products that are made out of non-ferrous materials. I'm including stainless steel in that list, even though it contains iron. So products that don't contain cast iron, black iron, or steel are the type I'm looking for.

Here are the component categories I've come up with. I'll start off the list by including one make or model in each category. Hoping others can add to the list.

Pumps (plenty of stainless steel pumps, but including this here in case there are makes/models made from other materials)

  • Taco stainless steel pumps

Magnetic dirt separators

  • Caleffi DIRTMAG (brass or brass and nylon models)

Hydraulic separators (including those with built in magnetic dirt separators)

  • Spirotherm Spirovent Quad (brass models)

Expansion tanks

  • Calefactio bladder tanks (instead of diaphragm)

Check valves

  • Caleffi servicable check valves (stainless steel and copper/brass)

Thanks for any help in filling out the list. Please add any component categories commonly used in modern hydronic systems, if I left any out.



  • hot_rod
    hot_rod Member Posts: 22,474

    I read about the relative area effect in some of the CDA research, Copper Development Association

    The analogy they use

    A ship in the ocean built with a steel hull has a single copper rivet. The hull will see very little corrosion with that dielectric connection. Salt water is an excellent electrolyte for those two metals far apart on the periodic table

    Now build a ship hull out of copper, add a single steel rivet. The rivet would corrode very quickly in sea water.

    Their point being, the smaller amount of sacrificial metal, the less nobel steel in this example, the more aggressive the corrosion of that part.

    In large steel pipe iron radiator systems not much electrolysis corrosion, until some adds some copper.

    Bottom line, I suppose, use 100% non ferrous, or risk accelerated corrosion with a small amount of ferrous metal in the system. Stainless steel or brass nipples for example instead of steel.

    The conductivity if the fluid plays a part also. The DI water will slow corrosion potential, however the low ph will need to stabilize. It does this by pulling ions from the weak metals used in the system until it balances

    corrosion inhibitors in the hydronic conditioners add a film otovider to protect new metal surfaces from attack. I feel it is an important part of hydronic conditioners, as are the ph buffers for that aggressive fill water.

    so, to make a long story long🥴

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,166
    edited March 2023

    I believe that you will be spending more money than necessary. As long as the pipes, fittings and tubing has an oxygen barrior like Steel pipe, Copper pipe, HePEX or PEX-Alu-PEX tubing, there is no need for those non-ferrous parts. There are 100+ year old Steel Piping systems that are connected to aluminum block boilers with no real issues. Get the water chemistry right at the first fill up and leave it alone. Only need to verify chemistry every couple years… if that, or if you need to drain and refill the system with new water for a repair.

    Once the initial oxygen oxidizes the ferrous components, the deed is done and the boiler water stays oxygen free as long as it is in there. But if you have extra money and don't mind spending it, I will PM you my address!!! I also accept: ApplePay, CashApp, Direct deposit, PayPal, Venmo, and Zelle.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • hot_rod
    hot_rod Member Posts: 22,474

    ma nature gates any imbalance. If she sees an o2 starved condition, she will jump thru hoops, or Pex tube, to balance that.

    So I propose all hydronic systems with any ferrous metals have some magnetite or hemitite in them

    Older cast boilers just held that heavy metal particle in the bottom of sections.

    With today boiler technology may as well protect against the enevitable. Treat and repeat, add a mag Sep.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream