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Rinnai tankless gas water heater sizing charts

bob eck
bob eck Member Posts: 930
Where can I get sizing charts for Rinnai tankless gas water heaters. Thanks Bob


  • bob eck
    bob eck Member Posts: 930
    For residential Rinnai TGWH units
  • Zman
    Zman Member Posts: 7,569

    The sizing (GPM output) is just a function of BTU output and delta t.
    BTU/delta t/500 = GPM
    If you have a 200,000 BTU/hr 90% efficient unit with incoming water at 50 and outgoing water at 120, the math would look like this:
    200,000*.9 =180,000
    180,000/70/500 = 5.14 GPM

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein