Inline/duct Attic Fans - recommended quiet fans

[jonwestuk]

Hi,

Living in a 3 story town house, I realise that my top floor is going to get rather warm in the summer, especially now I have 300mm of insulation in the attic. I am therefore proposing to install attic fans into some of my rooms to draw out the hot air from the room and venting it outside.

I would very much like some recommendations on the different fan types that I should consider and particularly and recommendation on how I can reduce the noise to the bedrooms below.

Thanks,

Jon

 

[winston1]

Surely attic insulation will stop your house getting warm. It will prevent it cooling but in the UK it won't get warm to start with.

 

[PrenticeBoyofDerry]

I think natural ventilation is the best possible method.

 

[AndyPRK]

Interesting idea but think you would be better off with some ceiling fans to move the air about in the main bedrooms.

 

[jonwestuk]

There are quite a few examples of where this has worked well in hot parts of the US. I know for a fact that the temperature on the 3rd floor is much hotter than that of the 1st, 2nd or outside. As heat rises it is good to give it somewhere to go, if you want the rooms to cool. Many people point a regular fan towards the window to vent the heat out and pull the cooler air from the downstairs rooms. This works but it is not elegant.

The solution that many use is to have vents in the ceiling with duct fans which vent out of the soffit. These are controlled by a thermostatic switch so that the rooms can be cooled throughout the day ready for the evening.

------------
Back to the original question though.

What are the best types of duct fan for quiet operation?

 

[jonwestuk]

Probably also worth noting....

I have lived in town houses in the UK my whole life, and owing to the sun coming in through the windows and the heat rising, the top floors often get crazily hot in the summer. So much so that when I was growing up I used to prefer to sleep on the floor on the ground floor as it was so much cooler.

 

[AndyPRK]

Yes I'm well aware of the problem of heat on the top floor with modern houses.

Due to the poor airflow of fans you would need it Running during the day as you say.

My worry would be heat escaping in the winter.

I removed a down lighter bulb in a cloakroom this mild winter.
This caused air to escape into the roof space and made a significant drop in room temp.

This put me off fitting an extractor fan in there!

As mentioned I have a ceiling fan in bedroom and am pleased with the result.

 

[jonwestuk]

The loss of heat could indeed be an issue, but sticking a one way valve directly over the vent and surrounding the pipe and valve with insulation should mitigate this. After all, this is how the bathroom extractors all work!

 

[jonwestuk]

Just a quick update. I stuck a cheap toilet extractor fan in the attic extracting hot air through an unused flu when the thermostat is 30 + degrees. Although the fan is vastly undersized for the size of the room, I am still yielding a temperature drop of at least 10 degrees.

As a test I also used a new centrifugal fan which I am using for the bathroom to see if the temperature would drop on the top floor if I vented air outside. The results I have to say were impressive. Even when comparing temperatures when the windows were open with the fan off and on the temperature on the top floor dropped by about 7 degree, bringing the temperature to a comfortable level.

 

[EFLImpudence]

Surely, if the problem is that bad you don't actually require a fan, but merely vents in the ceiling - i.e. a controllable chimney.

Then physics will do the rest.

 

[jonwestuk]

Surely, if the problem is that bad you don't actually require a fan, but merely vents in the ceiling - i.e. a controllable chimney.

Then physics will do the rest.

Hmm - venting into a hotter attic, not sure how effective that is. I could put a chimney into the roof, but that is more expensive than a £12 fan and a £15 thermostat.

 

[EFLImpudence]

No, silly, outside where chimneys go.

Were you having the fan extracting into the loft?

 

[ekmdgrf]

Jonwestuk: I hate to be pedantic but heat does not rise. Air of a higher temperature will be less dense and so will rise above air of a lower temperature.