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Tankless Water Heater for Cast Iron Radiators?

joel_28 Member Posts: 21


  • Duane_4
    Duane_4 Member Posts: 1
    Tankless Water Heater for Cast Iron Radiators?

    I have an old house, currently heated by an oil-fired boiler with hot-water cast iron radiators. The oild tank is leaking, and we want to replace it with a natural gas system. Does anyone have experience with using a tankless hot water heater to provide hot water to cast iron radiators? I have one contractor telling me this is a great way to go, less expensive and very efficient. I have another contractor telling me that tankless hot water heaters don't have enough flow capacity to do a good job, and a boiler is really required. As a side note, our climate is moderate - very cold nights here might get down to 20F, but that is rare. Thanks.
  • J.C.A._3
    J.C.A._3 Member Posts: 2,981
    Start right.....

    Either do or have a heat loss done as the first step.

    From there...talk to a few different contractors. I highly suggest the "Find A Contractor" list here at the top of the page.

    I'm not a fan (personally) of using a water heater for/as a boiler as a rule....but that doesn't mean it can't be done. (IMHO...it shouldn't be done....but I digress)

    Cast iron radiators are one of the best way to heat a home. If you can match the radiators to heatloss knowing that they can work with far lower temps than a standard boiler(bang/bang) would provide, a mod/con boiler will be your best bet.

    Secondly...if you use the boiler to make your hot water...you'll eliminate yet another appliance from having to break down or be serviced.

    3rd...tighten the envelope first! Get your home to the lowest possible heat LOSS, and reap the benefits of using whichever boiler the best contractor can provide.

    Hope I helped. Chris
  • joel_28
    joel_28 Member Posts: 21
    1 word

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