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Vitodens 222-F noise

SwampgasSwampgas Posts: 11Member
About 3 years ago we had the Vitodens 222-F installed to supply DHW and the main floor radiant floor (wood) and lower level Runtal radiators. Everything was fine until I had the installing contractor come out for annual maintenance. It became a circus of leaks, errors and broken parts on what had been a perfectly functioning system. Not long after that I got a recall notice on the heat exchanger so I had them come out in the summer to replace that when it wouldn't be trouble to be without the boiler for a short period. Right after they exchanged the exchanger I noticed a loud humming noise coming from the boiler. I called them back out to look at it and they said it was just because the outdoor reset and indoor temp was such that it was making a pump run because the technician had taken it off of DHW only mode which is where I had it for the summer. Now that we are into the heating season I hear the humming all the time throughout the house. Before the exchange I don't recall ever hearing the system at all unless I was standing right next to it. The pump that seems to be making the noise is located inside the housing, not the circ pumps on the wall. It is the one that draws off the low loss header.

Any ideas what may be causing this noise and how to rectify it?


  • Paul PolletsPaul Pollets Posts: 3,201Member
    Do you have a 3 way mixing valve and motor actuator on heating circuit #2 for the radiant load ?
  • Paul PolletsPaul Pollets Posts: 3,201Member
    The HX replacement requires a careful purging of air in all circuits and the HX itself. Your system may be air-bound in several places. Pumps should not be making a noise.

  • I'd call your contractor back and ask them to call Viessmann technical support at (844)649-5886 to figure this out.

    Could be like Paul says: air. Could be low water pressure; should be 15-20 psi for a 1- to 2-story house. What does the gauge say on the front control panel. Is it in the green zone?
    Often wrong, never in doubt.

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  • SwampgasSwampgas Posts: 11Member
    The pressure is right around 15 psi. There is a Veissman mixing valve connecting the floor heat return, the floor (circuit 1) and the supply coming off the low loss header. The Runtal radiators for circuit 2 are supplied straight off the LLH. The LLH has an air vent on the top, would that eventually release the air from the system without having them come back to mess around? It's been humming like this for a few weeks now so I'm guessing not.

    Thanks for the help.
  • The air vent at the top of the LLH will vent air, but you've got to somehow get the air to move from where it's stuck to the LLH to be vented.

    Humming is not usually a sound caused by air. Air typically makes a sloshing sound. Humming comes from vibration; something out of balance or loose.

    Does the humming happen all the time or only when there is a call for heat or DHW?

    Get a technician out there and have them raise the pressure to 25psi and see what happens to the sound. Take it back down to 15psi once he's done.
    Often wrong, never in doubt.

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  • SwampgasSwampgas Posts: 11Member
    The humming is when there is a call for heat or when the outdoor reset tells the controller that there is a certain delta between outside and inside temp (according to the tech). No humming on call for DHW. Inside the cabinet there are two pumps, one for DHW which is nice and quiet and the other for the heat which is the humming culprit. I can tell it's that pump by the amount of vibration when I touch it. The further away from it I go the vibration lessens.

    I'll risk having the tech out again to see what happens.
  • If you'd care to share, let us know the outcome when it happens.

    Often wrong, never in doubt.

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