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gravity hot water boiler replacement

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Gasper
Gasper Member Posts: 148
in Radiant Heating
Is it possible to replace a cracked hot water boiler that was heating by gravity, with a new cast iron boiler, and continue to heat without a pump? A customer is requesting this, if possible. Thank you for any feedback.

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  • pecmsg
    pecmsg Member Posts: 4,845
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    Why?

    Ironman
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,523
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    You could and I have done it. I used a H B Smith BB-14 which was a large water content boiler. That was probably 40 years ago and it worked fine.

    Not sure you could find a boiler with a large enough water content today.
  • Ironman
    Ironman Member Posts: 7,376
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    That would be more trouble than it's worth. Why would someone wanna do this?

    A properly sized and installed mod/con works great on old gravity systems.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,523
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    The tappings in a modern boiler probably are not large enough for gravity flow. Pick a boiler and call the manufacturer and ask them
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,002
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    I've seen it done with a cast iron Peerless boiler.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Gasper
    Gasper Member Posts: 148
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    Tapping sizes were my first concern. Water volume of new vs old probably pretty important as well?
  • Gasper
    Gasper Member Posts: 148
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    We also, occasionally, have people asking if new boiler can be retrofitted with a power pile (like the old boiler they have) system. Any thoughts on that?
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,523
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    @Gasper
    I am sure a power pile conversion could be done they still use them in gas fireplaces etc.

    But, I am also sure it's not really legal
    Gasper
  • WMno57
    WMno57 Member Posts: 1,265
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    I'd buy one.

    Simple. Less to go wrong. Could be used off-grid. Would work in power outages. Smaller generator, smaller battery bank, smaller solar array.

    What is the MTBF for a Mod-Con? 12 Years?

    My current working Boiler is 70 years old.
    I DIY.
  • mattmia2
    mattmia2 Member Posts: 9,639
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    The older gas valves with the knob underneath to manually open them.

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