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Navien Combi Boiler NCB 190/080H Boiler Not Reaching Thermostat Temperatures

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NavienBoiler
NavienBoiler Member Posts: 2
in Radiant Heating

I just recently had a new Navien Combi Boiler installed and wired to 3 wifi thermostats for 3 seperate zones. The combi boiler is sized correctly for the size of my house at 2200 sf. In mid November I could dial up my temperature in my house to 70. Now in mid December with the temperatures colder the temperature in house will only reach 68 degrees when 70 is called for. My house is extremely well insulatated with closed cell foam upstairs and a foot of rockwool insulation downstairs. My boiler is constantly running trying to get to 70 but will only reach 68. Any help would be appreciated.

Thank you.

Comments

  • bjohnhy
    bjohnhy Member Posts: 144

    What sort of heat emitters do you have?

    Do you have a set back programmed into thermostat schedule? What model thermostat?

    Is there an outdoor reset function set up for this boiler?

  • NavienBoiler
    NavienBoiler Member Posts: 2

    The boiler serves radiant floor tubing throughout the house. I'm not sure what you mean by set back programed into the thermostat schedule. I have Watts Tekmar 561 thermostats but I do not have any schedule set or defined for these thermostats. Regarding the outdoor rest function, that is being installed on Monday.

  • neilc
    neilc Member Posts: 3,129
    edited December 24

    so what is your heating water setpoint temp now? raise it 5, 10 degrees

    known to beat dead horses
  • bjohnhy
    bjohnhy Member Posts: 144

    Raising the supply water temp 5 degrees may be all you need to do as @neilc suggests. Setting up and tuning the outdoor reset will also address this problem if its only related to supply temp. What temp have you been running?

    However, it could be related to flow problems. What are your supply and return water temperatures?

    3rd potential issue is lack of heat transfer from infloor piping to room. BUt if it worked last year fine, this is not your issue.

    I ask about the thermostat, as some of the "smart" thermostats will automatically dial you back a few degrees with their energy saving alogorithm.

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