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Nti boiler too much psi

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Sfam
Sfam Member Posts: 4
We removed our combo boiler nti to just use as a tankless for hot water. We went forced air. We removed all components from the steam heat. We have a ton of discharge from the purge valve which the psi is sitting around 20-30. How do we lower the psi on it 

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  • dko
    dko Member Posts: 611
    edited April 21
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    edit: I may be wrong

    Can you post your NTI model number
  • Jamie Hall
    Jamie Hall Member Posts: 23,455
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    Yes please. We need the model number. And I'm confused. This is the very first time I've encountered a combi being used for steam heat. Something just does not compute here.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    WMno57Mad Dog_2
  • pecmsg
    pecmsg Member Posts: 4,895
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    Sounds like a Heat Pump replaced everything.

    Sad very sad!
    WMno57SuperTech
  • WMno57
    WMno57 Member Posts: 1,349
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    Sfam said:

    We removed all components from the steam heat.

    I wonder if they removed the expansion tank?
    I DIY.
  • GGross
    GGross Member Posts: 1,072
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    can you take a picture of the install as well
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,113
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    He probably meant "system" heat..Mad Dog

  • Sfam
    Sfam Member Posts: 4
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  • Sfam
    Sfam Member Posts: 4
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    I don’t have a before pick still looking. For one. We used to have baseboard heat all around the house. We removed it all and closed everything up

  • Sfam
    Sfam Member Posts: 4
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    thanks everyone

  • Mustangman
    Mustangman Member Posts: 113
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    Im a little confused. Did you just abandon the heating side of the boiler and just are using the combi part of the boiler? If the boiler pressure is going up, you may have a bad plate heat exchanger. If it has a tiny hole, you are putting city water pressure in the boiler. Boiler pressure is much lower than city or well water so naturally the boiler pressur will rise… remember at 30 psi, the relief will dump. I assume that you checked and set the boiler pressure with the PRV? We get so many calls for boiler relief leaks or high boiler pressure. I tell the men its always one of 3 things. Bad fill valve that is over filling, water logged expansion tank, or bad relief from people yanking on the relief lever everytime they walk by it. Hope that helps.

  • GGross
    GGross Member Posts: 1,072
    edited April 23
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    You still need an expansion tank on the heating side of the boiler, looks like you put one on the domestic piping, but that tank never sees the boiler water.

    You need 2 relief valves total (one for DHW, and one for boiler), and at least an expansion tank on the boiler side, preferred to have one on the DHW side as well but not always necessary

    you need these things whether or not you are using the boiler for space heating, it is still a pressure vessel, and it is still being used to heat your water, both the DHW and boiler side are used to make DHW

    It's a good thing these boilers have built in safeties

  • Jamie Hall
    Jamie Hall Member Posts: 23,455
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    And I hope that you didn't drain the heating side of the system. I the heating side heat exchanger is dry, it will die a nasty and early death — if it hasn't already. Not sure quite how I would handle that situation, since the heat exchanger must have water in it — and that water must take the heat away from it, even when only the domestic side is calling.

    hmm…

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England