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Vitodens 200 question

I've got a new Vitodens 200 installed and with the temps dipping to 40 at night the boiler is making heat by morning. By late afternoon if the temps outside get above 55-60 the indoor temp will show 70 on the Vitotrol 300. The heating setpoint is set for 66 and the boiler will start heating water again later in the evening even though the temp in the house may still be 70. Obviously the boiler isn't heating the water much but I wonder why it's running at all if the temp on the Vitotrol is 4 degrees above setpoint. Is this normal? Do I just need to switch the program to DHW on days when outside temp will be above 50 and sunny?

Comments

  • GW
    GW Member Posts: 4,536
    That boiler is more sophisticated than most, you installed it? If yes, you picked a good boiler, not super easy for a newb to figure out. If a heating guy installed it can’t they come back and make it work?

    In any case-
    Are you using the DE outputs? Or simple old school Viessmann outdoor reset? Not sure what DHW has to do with your space heating question, unless things are really goofed up
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    [email protected]
  • gobucks823
    gobucks823 Member Posts: 24
    Yes I installed it. First Viessmann install I have done. I'm a pipefitter by trade but normally Im dealing with heating in an industrial scope.

    I'm using the outdoor reset.

    The DWH comment was just a question on switching the boiler to run in 'DHW only' mode when daytime temps are warm enough to keep house temp above heating setpoint.
  • Paul Pollets
    Paul Pollets Member Posts: 3,508
    edited October 2019
    Lower the heating curve if you're 4 degrees over setpoint. A reduction in the curve of .1 usually results in a 3 degree temperature change. I like to keep the DHW differential at 7 degrees. Once changes are made, leave it alone for at least 2 days so boiler computer can adapt to the change. Make sure the Vitotrol 300 thermostat has the sensor enabled.
  • GW
    GW Member Posts: 4,536
    check the BO settings
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    [email protected]
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,188
    And I thought you had 200 questions about Vitamins. ...and just spelled it wrong
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
  • gobucks823
    gobucks823 Member Posts: 24
    Thanks guys
  • Moose907
    Moose907 Member Posts: 2
    > @GW said:
    > check the BO settings

    Hi, I have a similar situation/system. The BO code should be what for the OP?
  • GW
    GW Member Posts: 4,536
    I would do 3
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    [email protected]
    Moose907
  • gobucks823
    gobucks823 Member Posts: 24
    I've got another question.....I live on Lake Erie and get some pretty fierce winds. When I'm getting strong North winds the boiler has trouble satisfying the setpoint with the current heating curve so I adjust it to compensate. A couple days later when it's now sunny and theres no wind sucking the heat off the house the indoor temps will creep past the setpoint. Is there coding that will shut off the burner when the setpoint is met but will continue to run the system pump? Unless I'm missing something I'm only finding the coding that will shut off the pumps when the setpoint is met. It would seem to make sense to keep the water circulating to use that heat.
  • GW
    GW Member Posts: 4,536
    You have an indoor sensor but you’re still drifting on temps? Should hold tight
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    [email protected]