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rinnai 75 combi mod range

jjwest
jjwest Member Posts: 6
in Gas Heating
Does anybody have an idea on the actual working modulation range of the ng Rinnai E75c? The unit I have always cuts out at about 25kbtu. The specs say it should go to 17kbtu. Is this normal for the Rinnai because of better combustion efficiency?

Comments

  • Aaron_in_Maine
    Aaron_in_Maine Member Posts: 315
    LP

    If your boiler is hooked to Propane it will not go as low as natural gas.

    There was an error rendering this rich post.

  • jjwest
    jjwest Member Posts: 6
    Natural Gaz

    Good guess, but no. It's NG. Is there any chance the computer thinks it's LP? The Rinnai tech laundry list hasn't found the problem yet so I was hoping for dumb mistake suggestions like "did you hook it up to propane?"
  • jjwest
    jjwest Member Posts: 6
    Natural Gaz

    Good guess, but no. It's NG. Is there any chance the computer thinks it's LP? The Rinnai tech laundry list hasn't found the problem yet so I was hoping for dumb mistake suggestions like "did you hook it up to propane?"
  • Aaron_in_Maine
    Aaron_in_Maine Member Posts: 315
    Possible

    It's possible, the conversion is a chip on the board and a orifice for the gas valve. It could have the wrong chip. The combustion numbers would be off if the orifice was in there. But the chip would keep it from modulating all the way down.

    There was an error rendering this rich post.

  • Jack
    Jack Member Posts: 1,049
    How are the gas pressures?

    Aaron is correct on the chip/orifice, but gas pressures enter into this as well. Was this unit factory supplied as NG or converted?
  • Jack
    Jack Member Posts: 1,049
    Another thing...

    Check the min. Input setting in the set-up procedure. Perhaps the min setting was re-set to a higher number.
  • jjwest
    jjwest Member Posts: 6
    Min mod setting

    What parameter # is this?



    Factory Gas



    I'm going to get another meter.



    Thanks
  • Jack
    Jack Member Posts: 1,049
    Was speaking with a firend

    and he suggested that you power it down and then up. The first thing that will show on start-up is the software version and it will show a 1 for ng or a P for propane. While unlikely perhaps there is a mix of orifiice/chip.



    Min/max setting is parameter 3. Reading is in kw, so X 3414 for btu.
  • jjwest
    jjwest Member Posts: 6
    Could the system just be under radiated?

    I don't see the delta causing it to shut down instead of mod down, but maybe I'm wrong. It is the correct software version. I thought parameter 3 was only for max fire.? When parameter 3 is at its lowest setting, it does fire at 17kbtu.
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