Hello folks. My 12KW unit seems to generate an annoying whirring noise [video] at the lowest modulation (25% according to VWZ AI) and 1200W electrical power consumption. This disappears when compressor starts working at higher modulation speed e.g. 35%+ and only fan can be heard. Is this normal?
Thanks!
That doesn’t sound typical to me, usually the unit should be quieter at lower modulation, not develop a distinct whine. It could be something like fan resonance, inverter noise, or vibration at that specific operating point. Might be worth checking mounting/clearances and raising it with Vaillant support if it’s consistent.
Thanks @Sarah_Wilson ! I had a call with Vaillant and they’ll send someone over. Since the unit is between 3 walls (but meeting necessary clearances in all directions), they suggested it might be due an acoustic effect generated within this space (standing wave?). If I put my ear just by the back compressor panel, I can audibly hear the whir which makes me think even if I could theoretically move the unit in the middle of the garden. I understand that my space could amplify sound by few db, but I’d like to be one of those ‘I stand by my unit and I barely hear it working’.
I’ll see what Vaillant folks will say and will report back!
The technician came, opened the case and checked the compressor noise (as it was running already with the lowest modulation exhibiting the issue). The compressor without the insulated panels is very noisy and although unit has heavy internal insulation, the compressor noise still escapes through front/back side where the opening is. That being said, he told me that it’s normal and options are to potentially block the noise by adding fence, etc. as my unit is in between 3 walls (with 2m front/1m side/1m back distances) and it’s what is most likely amplifying the frequency.
After he left, I put a 1m x 1,5m drywall sheet on the side of the compressor and lo and behold - this was enough to redirect the sound and get rid of the annoying buzz which was amplified through the open space we had. I’ll probably build an L shape enclosure from wood, covering the front and side of the unit (without blocking the fans) and this should be enough.