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Cast iron or steel boiler - which is best?

don_9 Member Posts: 395
I personally like a cast iron over a steel boiler.
Cast iron boiler are easier to clean,most have more then one are two passage to flue for better heat transfer,less
stand by losses.And did I mention how manly you feel after sittin it in place.

Steel boiler- most are tube,single vertical passage to flue
less heat transfer,more stand by loss because it hold more water,baffles that need to be replace every three to four years,unless specified most come vertical discharge so can
only installed in area with lots of head room.Can be a pain to clean after brushing all the soot out of the tube will need to pull burner to clean soot out of fire box.
They also don't last as long compared to a cast iron boiler.


  • D. T. Jones
    D. T. Jones Member Posts: 1
    Boiler design

    Is cast-iron or steel the best material for residential boiler heat exchanger design?
  • Jackchips
    Jackchips Member Posts: 344
    My late Father-in-law,

    who forgot more than I'll ever learn always told me that cast iron boiler sections are installed with steel push nipples which meant it didn't matter to him which you used. You'll get responses from some very bright people on this site but I think "Bill" knew what he was talking about.
  • Frank_17
    Frank_17 Member Posts: 107
    steel vs cast iron

    Heres the first opinion and I, m sure many will agree with me, and just as many will disagree.

    1)most all boilers now come with a lifetime warranty.
    2)cast retains heat longer than steel
    3) steel heats quicker than cast
    so I feel , 1)If you have a cold start boiler,steel is more economical, not as much standby loss.
    2)if you have a tankless, cast is better.
    3) if you're the guy hauling it down to the basement-STEEL is BY FAR BETTER.!!!!!!!!!!
  • John@Reliable
    John@Reliable Member Posts: 379
    Which is better!

    If price matters steel is the one.Selling the house steel is the one,what a unit that will last 40 years cast is the one!I find most steel boilers are done after 20 years but still work on 50 year old cast iron boilers all the time. The different in price is under 500.00
  • John@Reliable
    John@Reliable Member Posts: 379

    Jack,I don't know about all brands,but Burnham has cast iron nipples which expand at the same rate as the boiler.
  • heatboy
    heatboy Member Posts: 1,468

    The material the boiler is made of matters much less than the design of said boiler. My most efficient, highest quality boiler, the Vitola, is made primarily of steel. But I have seen many landfill boilers that were made of steel. All sectional boilers are made of cast iron and have varying designs. They range from great to landfill, also.

    As far as durability and duration, it matters little what the boiler is made of. If it’s installed incorrectly, it’s not going to last very long. Would I put any boiler in a low temperature application with out provisions for boiler protection? Of course not.

    There is no right or wrong answer to this, just a right or wrong way to install it.

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