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Tankless Boiler Makeup Water

Mjplumbing
Mjplumbing Member Posts: 6
in Gas Heating
I understand it is correct to fill the system a the point of no pressure where the expansion tank is installed on the system...why is there an internal fill valve built into Navien's Combi Boiler if you are technically supposed to fill the system where the expansion tank is installed on the system?

Comments

  • Ironman
    Ironman Member Posts: 7,550
    It's for convenience. The system doesn't have to be filled a the PONPC; the circulator should "pump away" from that point, but the fill can be done at any point.

    With a cast iron boiler, it's a good practice to have the fill on the supply to prevent thermal shock to a hot block.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    Mjplumbing
  • Ironman
    Ironman Member Posts: 7,550
    Also, that boiler has an automatic internal fill valve, so an external one is not required. However, You still need the backflow preventer.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    Mjplumbing
  • Mjplumbing
    Mjplumbing Member Posts: 6
    I totally agree. looks like to me this combi unit fills the system on suction side of pimp thats built in..?

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