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Navien guys, what is this M icon w/ circular arrows?

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TT_Vert
TT_Vert Member Posts: 57
edited April 2021 in Radiant Heating
I assumed it was for either the system or loop circs but it never turns on. This is NOT in the manual anywhere and I've even watched tons of vids hoping someone would mention it but no love. Also does anyone know exactly what S and R mean? I had heard in a video that it's suppose to mean something like there is a call for the boiler but i'm not entirely sure. Maybe it illuminates when it displays the inlet vs. outlet water temp?




Thanks
Dave

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  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,834
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    Could be an elaborate way of typing a "W"

    But the first thing that comes to mind is a motor. Now, what motor is anybody's guess? Could be the combustion fan motor. Does it have anything in the manual? Most manuals are online. All you need the model number.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • kenkim
    kenkim Member Posts: 2
    edited April 2021
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    If the "M" is displayed on your water heater, it means that your water heater is the Master unit of the cascade system.

    Also, S Indicates supply water control status and R Indicates Return water control.

    All the icons on the display are explained in the User's information Manual.
  • TT_Vert
    TT_Vert Member Posts: 57
    edited April 2021
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    Kenkim, I was going to provide you a link to the manual and I downloaded a different one (I was looking at the installation manual, unaware there was also a "users manual" from Navien and sure enough the link I was going to send you does have them. That's a pretty big fail on my part, sorry guys. What exactly does "return water control status" mean? Does that mean the temp currently displayed is return water temp?




  • kenkim
    kenkim Member Posts: 2
    edited April 2021
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    They are temperature control for supply water (S down) and return water (R up). You can activate or dis-activate these features by setting DIP switches (probably DIP Switch 2, depending on models).
  • TT_Vert
    TT_Vert Member Posts: 57
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    kenkim said:

    They are temperature control for supply water (S down) and return water (R up). You can activate or dis-activate these features by setting DIP switches (probably DIP Switch 2, depending on models).

    I'm not exactly following. Do you mean while using external supply/return water temp sensors? Those are the only DIP switches that pertain to supply/return. I have those illuminating w/o using any external temp sensors currently. Do those generally illuminate when you have it set to either satisfy return or supply water temp when NOT using any external sensor?

    Dave

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