Author Topic: air vent air extractor above my flat  (Read 3785 times)

adrienne

  • Guest
air vent air extractor above my flat
« on: January 03, 2009, 04:09:14 PM »
Hi,

I live on the top floor of a four story building. All the flats bathrooms do not have windows. Half the flats in the block are owned by the local council. The council has an air extractor unit that extracts air from the bathroom. The unit in the bathroom is circular about 14c.m across.

The air vent is a very large industrial type of machine. It has two motors that shift from left to right at diferent times. After many years of complaning we measured the decibels at 49db. They replaced this expensive motor with another bigger motor. We only have 20 one bedroom flats in the building. I thought it unnecessary for such a large motor.

The aitr vent runs through a cavity which is met with pipes from the water tank also on the roof. Some nights the two become too unbearable.
The pipes rattle, the tank fills up and the air vent vibrates.

The only problem is it is on a nature reserve in London and very beautiful. It is hard to come by such beauty and i dont want to move.

I fitted a fire door as I thought the noise above the passge outside my door was the loudest and might help. It did nothing.

I arranged for the motor to be slowed down. It is running at a unit of 5, which is the legal limit.

I swopped the bedroom and lounge as this reduces one of the noises.

I am now directly below the air vent. The ceiling and walls are so thin i can hear every word from the neighbours.

The noise must be below 15db BUT as `i put my head on to the pillow I can hear he vibration BUT NOT when i am standing up.

I conclude that my ear is parrallel to the ceiling and this could be the problem.

As I do not own the flat I was wondering if the Convoluted Acoustic Foam 4inch thick glued to the ceiling is an option. The area is around 4metres x 4 metres.

Will this make a difference?
Can I glue it straight to my the ceiling?
Is it easy to remove the glue and foam when moving?

Many thanks

Any advise would help as i am near collapse from lack of sleep.

Adrienne ::) ::) :o :'(

johnbergstromslc

  • Guest
Re: air vent air extractor above my flat
« Reply #1 on: January 03, 2009, 11:44:33 PM »

The noise must be below 15db BUT as `i put my head on to the pillow I can hear he vibration BUT NOT when i am standing up.

I conclude that my ear is parrallel to the ceiling and this could be the problem.


The reason you can hear the vibration when you're lying down is probably that your bed is in a corner, or near a corner, where the sound (especially low-frequency sound) is focused and reflected by the 90 degree angle of the walls.  With low-frequency noise in particular, the orientation of your ear with respect to the origin of sound makes little difference - the sound is omnidirectional.

Since, as you say, the noise bothering you is 'below 15 dB', I would advise not attempting to soundproof to a lower dB (an expensive and nearly impossible task in a unit where you're not authorized to make the structural changes you require) but raising the noise level in your flat to 30-40 dB with a white-noise machine.  Your brain will quickly get used to the noise (it sounds like a forced-air space heater) and even at it's loudest setting, it won't drown out the alarm clock.  I have an extremely quiet bedroom but I still use one. Sometimes 'too quiet' can be unnerving, too.  A 30 dB transient noise spike in a 0 dB room can wake you right up!!

Another thing you may want to try is asking the building management to mount the motor on vibration isolators, instead of directly to the frame of the building.  That would help a lot..