Bit of a curious thread but would value any advice as to solving the annoying hum transmitted through the wall of our house from an external hung air conditioning unit. Had a Dakin split unit installed 18 months ago and it works brilliantly, heating in the winter and cooling in the summer. Annoyingly the outside unit now seems to produce an amplified hum in the fabric of the building- heard in several rooms. It is attached by brackets directly fixed to the first floor bedroom wall. The installers have so far replaced the rubber feet with no effect and now are suggesting placing it on an acoustic platform on the flat roof of a downstairs room. I have to respect their informed opinion but do not have much confidence in the suggested way forward.
The best solution is to relocate the external unit. Alternatively use Tico acoustic isolation mounts and pads everywhere there is contact. Generic rubber mounts are not suitable. Installing directly onto a wall of a residential premise would not be a design methodology I would recommend without knowledge of the structure. Relocate and isolate to somewhere not directly connected to your home. The flat roof is just transferring the issue elsewhere. ie the room below. Moving it is your best solution. I would also recommend an acoustic enclosure and dont skimp on regular mantenance periods. But if you cannot, then Tico are pretty much the industry lead in regards to this type of isolation. tico - https://anti-vibration.solutions/ Acoustic enclosure (residential) - https://www.ice-ltd.co.uk/air-conditioning/air-conditioning-acoustic-enclosures/
FirT try 6 mm rubber strip between the brackets and the wall so you are double isolating But maybe you have a balance issue on the fan or a problem with pump if it worked without issue for 18 months..
Good food for thought and will follow up on suggestions. Thanks. S'pose really would like to find an interested fitter who would sort the problem. The present guys will obviously charge every time the unit has to be taken off the brackets and refitted so want a level of confidence in the solution.
Sorry only just seen this.... I doubt it's the fan, if it can be felt through the fabric of the building. It will be the compressor, this has a large off centre rotating mass. Being a recent Daikin it will be under inverter control, so you should hear the pitch change with heat load. 1. Ensure that the bracket is not taught and acting like a drum skin. Is the wall a brick wall or stud? Photos? Professional unistrut brackets or a cheap pressed steel Are the pipes pulled tight? Use these sort of professional isolation fittings.... £100 trade price... No issue with moving a 5kW condenser to a flat roof.... I've got 100's of them working without an issue.... We always mount on proper professional mounts like this.... adding more mats where required.
The compressor (pig in the trade) is a sealed unit.... the off centre weight is part of the design.... I've had them make a vibration issue / compliant before, but always easily solved. Sometimes, just moving the outdoor unit brackets 6" or loosening all the mounting bolts and retightening.
You are a long away from me..... Take some photo's, especially the brackets that hang the outdoor unit. PM me if you'd prefer to take this conversation private.
