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Navien NCB 240E Space Heating not Turning on

choag Member Posts: 1
I had a Navien combi unit installed about two months ago. After it was installed everything seemed to work fine including the space heating side of the unit. In the last few weeks it has started to get cold so I turned on the heat via thermostat only to find that cranking up the thermostat does not engage space heating. I confirmed that the T/T connection on the Navien is getting 120V when the thermostat is calling for heat. I can also confirm that DHW is working fine and even that the space heating works when I make it permanent by turning DIP switch #7 on located on the PCB. In normal mode where the Navien is controlled by a zone controller linked to thermostats (DIP Switch #7 off) it does not seem to kick on. Any ideas on what could be going on? MY only thought left is that it is the PCB itself.


    JUGHNE Member Posts: 11,061
    Someone installed this for you 2 months ago?

    Where are they?
    I would not even adjust or change anything, but call them back.
    If you made any changes the installer can point fingers at you as to why it doesn't work. IMO.