Low drone from flat roof mounted air conditioning unit


Postby Phil Lucas » Mon Dec 22, 2008 12:56 pm

I have just installed an air con unit on a flat roof of my house. Construction is fairly basic: bitumen covered ply on 7" wooden joists with 12.5mm plasterboard on the underside of the joists forming the ceiling of the room below. The air con unit is mounted on hard rubber mounts on a metal stand which has four one 8"x8"square pad feet, each foot sitting on a thick solid rubber sole. Inside, we can hear a low frequency drone. I am about to renovate the rooms below, so I would be most grateful if someone would suggest a way of reducing the fan drone noise.

Should I try to decouple the air con unit some more? Perhaps by putting lead sheet or cork board under the feet?

Should I decouple a sound insulation ceiling board from the joists using Z-bars?

Should I put as much dense firbre wool matting between the joists as possible?

Many thanks, Phil
Phil Lucas
Rank: Labourer
Progress to next rank:
0%
Posts: 1
Joined: Mon Dec 22, 2008 12:44 pm

Sponsor

Simply Build It

Postby stoneyboy » Tue Dec 23, 2008 6:21 pm

Phil Lucas,
Can only suggest you get hold of some 25mm thick foam rubber sheet and some 300mm square paving slabs. Use these to form large bearer for the existing feet.
end
stoneyboy
Rank: Project Manager
Posts: 2742
Joined: Wed Dec 10, 2008 6:44 pm

Postby Perry525 » Sat Jan 03, 2009 6:35 pm

You need to identify if the sound is airborne or via the fabric of the building.
If airborne and via the windows then secondary glazing will probably solve the problem.
If transmitted via the fabric of the building, then you need to de couple the air conditioner from the roof.
Placing the air conditioner on a tray suspended by several springs from a frame, or spreading the load over a wider area using softer foam rubber will solve the problem.
Perry525
Rank: Site Agent
Progress to next rank:
46.8%
Posts: 734
Joined: Fri Jul 06, 2007 7:35 pm

Postby TheDoctor5 » Wed Jan 28, 2009 10:27 am

If you type the key words of your question into our search box to the left of the site you may find the answer is already posted or is in the DIY projects section of the website. Every post goes through a monitoring process and using the search box may speed up your answer.
TheDoctor5
Posts: 1382
Joined: Tue Jan 20, 2009 9:17 am

Display posts from previous
Sort by
Order by



  • DIY How to Project Guides

  • DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!



 


  • Related Topics