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HX tube replacement

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  • HX tube replacement

    Hi all,
    Wondering if you can help me. I have removed the boiler from a Nuova Simonelli Program 2gp that I am rebuilding. I've sent it out to quote for replacing the heat exchanger tubes that are brazed into the boiler. The tubes have been fractured, allowing water from the boiler to go directly into the group head.

    What I need to know is, Will the inner diameter, outer diameter or thickness of the replacement tubes affect my brew temperature? I'm not talking about the replaceable tubes that thread into the bottom, these are the tubes that are soldered into the boiler, that the replaceable tubes thread into. I am asking because I need to advise the repair shop whether these dimensions are critical so they can select the appropriate size pipe to braze into the boiler. I suspect a metric sized pipe will be harder to find with me being in Canada, so if they can go with a SAE fractional sized pipe that might save me some time and money.

    What do you all think? The Nuova Distribution parts price pdf shows a replacement boiler for this machine priced at $640.10 USD but I have not asked about availability and shipping costs. Has anyone had this done?


  • #2
    Pic of the boiler. The tubes in question are inside, running diagonally through. Once the scale was dumped out I did not see a huge amount of pitting but the tubes are cracked and the near one had a piece missing.
    Attached Files


    • #3
      In theory you should be able to adjust for any variation so long as the replacement HX pipes are "close enough" but IANACST (I am not a coffee service tech), maybe get one quote for "critical" size and one for "close enough".


      • #4
        Thank you Sir I will do just that. Cheers


        • #5
          Re: HX tube replacement

          The tube diameter and thickness will definitely affect the heat transfer, however how critical it will be is hard to say. It will depend on how the temperature is controlled, and how much "headroom" there is in the design.

          My guess (as someone who is more familiar with industrial exchangers) is that small variations will probably be ok. The design looks rather crude anyway.