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Is This 'Storage Rust' on Section of New Boiler?

D107
D107 Member Posts: 1,849
edited April 2019 in Gas Heating
Month-old install; I expect final tuneup and control tweaks to be finished tomorrow. Peerless MI-03; looking forward to seeing significant savings over old oversized boiler. Yesterday I took a look at the cast iron sections and found one apparently with rust. What does this look like? Should it be cleaned up? This section is on same side as the return. When boiler was first installed for a few days I did smell some kind of mild chemical steam-humid-smell but attributed it to the inhibitor and de-mineralizer installed in the system water.


Comments

  • Steamhead
    Steamhead Member Posts: 16,796
    Yes. It's just on the surface, won't affect the boiler's lifespan. Don't worry.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
    D107Intplm.Rich_49ethicalpaul
  • Tim McElwain
    Tim McElwain Member Posts: 4,612
    Watch out that it did not get hit with very low temperature on the return. That can sometimes cause this to happen. Other than that it is probably okay.
    D107
  • D107
    D107 Member Posts: 1,849
    @Tim McElwain thanks--how would I tell what the cause is? Or tell if it's surface rust or worse? The Hydrostat 3200+ has a circulator hold feature.
  • JohnNY
    JohnNY Member Posts: 3,226
    It's not a problem. I see it all the time.
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.
    Classes
    D107
  • Tinman
    Tinman Member Posts: 2,808
    The two on the right are actually the unusual ones.
    Steve Minnich
    D107JohnNYRich_49ethicalpaul
  • mikeg2015
    mikeg2015 Member Posts: 1,194
    edited April 2019
    It’s so even and consistent that I’d guess it rusted at the factory. They made a batch of left end sections that sat on a pallet all winter then humidity condensed on them that spring or something like that.

    To save costs, they probably have to order batches of each section type (right, left, middle) in quantities of maybe 500 (total guess) or more or as long as a mold set will produce before rebuild/replacement or whatever determines a run length at the foundry.
    D107
  • D107
    D107 Member Posts: 1,849
    @mikeg2015 I took a look under the boiler and found what look like some rust spots on the cement block, and also--other photo not that clear--two rust marks on one of the firing tubes, which I would assume have come from the sections above.

    Makes me wonder, maybe a leak between sections that has since sealed itself with rust? Or if somehow outside water touched the rusted section and dripped down? We have a water meter on the feed you can read down to .01 gallon showing no water lost at least in a few weeks since I noted the reading. See photos.





  • Tim McElwain
    Tim McElwain Member Posts: 4,612
    Is this on the return side of the boiler. If so there is a possibility of condensation if there is a drop in temperature of the water returning to the boiler. Anything less than 140 degrees can start to condense and cause evidence of water which is actually the condensate and not a water leak. What is the temperature of the water leaving the boiler and the water returning? It should typically be as close to a 20 degree (delta T) difference. As the return temperature drops from the 20 degrees the potential for condensing increases.
    D107
  • D107
    D107 Member Posts: 1,849
    Yes, on return side. I've always heard that as long as temp gets above 135 or so within 10 minutes there shouldn't be a problem. Peerless installs a hydrostat 3200+ on the boiler which has a 'circulator hold' feature which will not allow circ to run until boiler temp reaches 125, and will then shut it off when it falls to 115. Possibly similar to Buderus' Logamatic 'Pump logic'. I know those are low numbers but apparently Peerless sanctions it. Two of three of our zones are cast iron so there is quite an initial cold return, esp in shoulder season where heat cycles are farther apart. (Heat loss 38K, more likely 30K.) We don't have t-stat setbacks and I think within ten minutes or so return temps are ok but will have to watch this next season.
  • mikeg2015
    mikeg2015 Member Posts: 1,194
    Could add a aquastat in series with the circulator so it doesn’t come on until above 125 at the boiler.
  • Zman
    Zman Member Posts: 7,561
    D107 said:

    Month-old install; I expect final tuneup and control tweaks to be finished tomorrow. Peerless MI-03; looking forward to seeing significant savings over old oversized boiler. Yesterday I took a look at the cast iron sections and found one apparently with rust. What does this look like? Should it be cleaned up? This section is on same side as the return. When boiler was first installed for a few days I did smell some kind of mild chemical steam-humid-smell but attributed it to the inhibitor and de-mineralizer installed in the system water.


    I think the the factory stored those end sections longer or in a more humid warehouse than the others. You would have to be returning super cold water (50 degrees?) to get condensation on the outside. The water would then need to warm up instantly as it passed to the next section. I just don't see it.

    If you wipe the 2 unrusted sections with mineral spirits to get the oils off and then spray them with a mist of water, you will get them to match nicely :)
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    D107
  • D107
    D107 Member Posts: 1,849
    @Zman Thanks for clarifying the physics of this--something we homeowners can't always visiualize since we don't work with boilers everyday. So the other good news I take from your post is that even where there is condensate arising from low return temps, that is all external to the system water in boiler, piping, etc. --fire-side only..

    The only question I have is that I have heard rust once started is a continual process that never stops, so should the rust on that section be removed/cleaned up? Or if it/s just from storage is the rust process so slow--and maybe inevitable with cast iron that is exposed to sometimes-humid summer ny air--that it's not an issue?
  • Zman
    Zman Member Posts: 7,561
    If you are getting low return temps, the damage would be on the fire side of the boiler and inside the vent.
    I would not worry about light rusting on the outside of the sections.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    D107
  • Tim McElwain
    Tim McElwain Member Posts: 4,612
    @d107 you can reach me at my e-mail address timmcelwain@gastcri.com .
    D107