Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Phase 3

Maynard Member Posts: 74
Can A Phase 3 Indirect Cause Rusty Hot Water? I Thought Stainless Steel Does Not Rust?


  • Big Ed_3
    Big Ed_3 Member Posts: 170
    Hi Tempertures

    Running water heaters on higher temperatures , above 120*will cause solids to drop out of solution ......

    Don't forget the rest of the house system . Galvanized piping and miss placed iron fittings....

  • Perry_3
    Perry_3 Member Posts: 498
    Yes, SS can rustt...

    I don't know what a "Phase 3" is....

    But, the 400 series of SS does rust rather easily (but rarely rust through). That is why "modern" SS exhaust systems are rusty (but do not normally rust through); and why the flue liner on atmoshperic furnaces and boilers can get a rust layer on them.

    300 series SS can rust under some very special situations: like destroying the inhibiting chromium oxide layer and having chemicals that suppress the chrome from oxidizing to form the protective layer. However, I am not sure how in a normal home heating environment that you would have the chemicals present that would make 300 series SS rust; and the Boiler Mft should have ensured that its products were OK from the factory.


  • hr
    hr Member Posts: 6,106
    Is it a new tank, and or problem?

    as you know the outer tank is steel on that style and brand. Could it have a leak? Pressure gauges and relief valves could tell.

    What about any steel fittings in the pipes? Or an iron bodied recirc pump.

    hot rod

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • Maynard
    Maynard Member Posts: 74
    Phase 111

    11 year old tank. No galvanized or steel nipples or fittings in domestic lines. Cut into domestic hot water line coming out of top of Phase 111...ran into pail and water came out very rusty.
  • hr
    hr Member Posts: 6,106
    Guess you shouldn't have cut into 'er

    Sometimes the tanks will get rust or sediment in them from the water source. It will stay at the bottom just fine until you open a very large draw. A full open condition can cause enough flow to the bottom to stir up the bottom crud.

    Same thing when you tip an old tank over or on it's side to drain them.

    Or something up stream of your tank has been "stired" ?

    A break in the city main supply pipe somewhere? A well tank going south?

    There is a procedure for filling that tank in tank type of indirect to prevent damaging the inner tank. What is the pressure on the boiler side of the tank?

    Got an installation manual handy?

    hot rod

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • Cosmo_3
    Cosmo_3 Member Posts: 845
    I didn't remember seeing that before

    I didn't remember seeing that before in the instructions, though on a recent install when I finally did, it did make a lot of sense to me.

    I remember hearing about some failures of the steel tank back 5 or so years ago, maybe this was one of the possible issues?

  • Home Depot Employee
    Home Depot Employee Member Posts: 329
    Well or public?

    Did you mention this was municipal water supply or well.
    If well, theres your problem
    If Municipal, was there a recent fire or hydrant flushing in you area, if so, there is your problem
  • bigwilly104
    bigwilly104 Member Posts: 50
    FIne Iron

    particles in water will cause this. I have a customer who has well water that was clear but slightly sulferic. The water guy put in tanks with airerators and ozone generators. this solved the sulfur problem but the fine iron in the water rusted and turned the water brown. This was corrected but the boiler continued to turn the water brown. This is a chemical reaction that I don't under stand but se alot in my area. When water with fine iron deposits is heated fast it rusts and even collects together to form heavy deposits. I would take a water sample to a water specialist and se what they say. I used a water softener in a comercial building and it worked great. Also if the tankless is new and the problem starten with the tankless standerd water heaters don't have the effect as much. Or the iron will settle in the tank.
  • Aidan (UK)
    Aidan (UK) Member Posts: 290

    There is a form of bacteria that thrive in hot water with an elevated soluble iron content. They feed on the iron and the rust is the by product of digestion. If its just the hot water side, this is probably the cause and its probably not the municipal system.

    See the attached bulletin from AO Smith for more info.
This discussion has been closed.