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Viessmann wiring question

There are three high temp baseboard circuits and you're bypassing the Comfortrol™ unit and allowing the boiler to heat to your fixed maximum temp when any of them call by using the "external call for heat" function. Why do you want to do that?

Set your reset curve for the baseboard and let the mixing valve do its job to supply the other (lower temp) radiation. That way the Comfortrol™ is doing its job all of the time and your baseboard zones will run for longer periods with lower space temp fluctuation. Your supply temp will be lower as well, because in the way you describe the b/b zones no longer have reset.

If you must use that external call, you would want your low-temp (mixed) circuit pump running whenever THAT zone needs heat.

IMHO this sounds like a <I>very</I> poor way to use a Vitodens...


  • Kritz_3
    Kritz_3 Member Posts: 85
    Vitodens 200 wiring question

    The system contains one mixing valve for rad. and three high
    temp circuts for baseboard and a vitocell 100. When there is a
    call the rad manafold pulls in a relay through a multi relay board
    that will make x4.1 and x4.2. But what enables the circulator for
    the mixing valve circut. Is this energized via a temperatue drop?
    The rad circut has a pressure bypass valve. Does the(rad.) pump run when any of the other high temp. circuts are calling as well?
    Should the mixing valve get it's own power circut or can it be run off the same outlet the power supply is on, since it has the LWCO
    I think it should be on one and the same.
  • Ted_5
    Ted_5 Member Posts: 272
    The external heat demand

    is only used for things like plate heat exchangers or limited use fan coils things like that, not as a "TT" conection! Call your Rep. or Viessmann to get the right way to do it.

    WI. Viessmann rep.
  • S Ebels
    S Ebels Member Posts: 2,322
    You got questions

    We got answers, but we need a little info to get started.

    First, is this a Viessmann mix valve? Gotta know that before anything else. If it is, you should have an expansion board in the Viessmann control module to run the mixing valve circulator.

    Second, are you using a low loss header? This also will make a difference on how the system is piped and controlled.

    The best way to run your setup is to let the boiler run itself. Turning it "on/off" with the 4.1 and 4.2 connection will not let the Vito "learn" the system. It's not the way that boiler was designed to operate. It's not a dumb on and off type boiler. It will think and learn and to do that it needs to be installed the right way.
  • Kritz_3
    Kritz_3 Member Posts: 85
    Vitodens wiring

    Thanks all, I spoke to my rep and he gave me the skinny. Yes it has a LLH, Viessmann MX/Valve with exp. board. I will let the
    Vito learn the house and the only dumb one here is me or was me
    after being set straight. Thanks again!
  • S Ebels
    S Ebels Member Posts: 2,322
    Obviously, you're not dumb

    You were smart enough to ask.

    You were smart enough to understand what you were being told .

    You were smart enough to accept some good advice.

    You were smart enough to learn something new.

    Nope, you don't sound dumb to me. The dumb ones are those who are too proud and stubborn to ask, learn and change.

    Good luck and Happy Holidays to you.
This discussion has been closed.