Results 1 to 7 of 7
  1. #1
    Join Date
    Nov 2010
    Location
    Melbourne
    Posts
    1

    Default Whirlybird Ventilation

    Hi, I have recently fitted a "whirlybird" to my roof, however as my eaves are asbestos, I'm wondering about alternative methods of providing "flow-through" to the ceiling cavity. Fitting internal vents to the ceiling has been mentioned, but I've read this may actually cause problems with hot air pushing down through the vent(s) into the house. Any ideas would be appreciated!

  2. #2
    Join Date
    Aug 2003
    Location
    Pambula
    Age
    59
    Posts
    5,026

    Default

    Western rotary vents actually suck air out of your roof space, not pull it in, so you're not going to have hot air "pushing down". However the reverse will happen and if you have open vents in your ceiling, the vent will suck the hot air out of your room in winter, which you obviously don't want.

    I think that you really don't want the vent sucking air out of your room because it will just be replaced with warm air from outside - these things are designed to work by expelling the hot air from your roof space, so you really want vents to the outside, either through the eaves or through the roof. Or if you have gables you can install a gable vent.

    You might find that it works well enough without vents because a roof space is rarely air tight anyway.
    "I don't practice what I preach because I'm not the kind of person I'm preaching to."

  3. #3
    Join Date
    Sep 2008
    Location
    Melbourne
    Posts
    19

    Default

    I have 2 fitted without any additional vents, and they spin day and night. There is more than enough air flow with a natural roof.

  4. #4
    Join Date
    Apr 2008
    Location
    Perth
    Age
    43
    Posts
    0

    Default

    If you've got a tile roof, you can probably get away without puting in the vents. They would make the ventilation more efficent but hey will still work anyway... Stick you head up in the roof space, if you can see lots of light getting in, its probably a good bet there is also room for plenty of air to get in also..

    If you've got a tin roof - that changes things.

    I've 2 whirlybirds on the roof of my folks place and it made a noticable difference, I then put the eave vents in, they made a diffence but not a significant as the difference when i put the first whirly in.

    I've even got one of the clear plactic ones and put it in the roof of my shed as a vent/skylight... Definately worth doing
    Rgds
    Rob.


    Never underestimate the power of human stupidity
    Common Sense, Isn't quite so common
    Adapt, Improvise and Overcome

  5. #5
    Join Date
    Nov 2007
    Location
    Mt Crosby, Brisbane
    Posts
    316

    Default

    They spin when the wind is blowing. Any wind if the bearings are good.

    Hot air does not sink. Heat can radiate through still air. You would need a lot of heat and very little flow to get roof heat down into the living space. It would be radiating through the ceiling more than the vents.

    If the air in your house is cooler than the air outside and you vent in the ceiling there is a danger hotter air will be drawn in and dump energy or mix with the cooler air within before venting up through the roof. Usually however this isn't the case (unless you've got an air conditioner going) and the net effect will be cooler and fesher air within the house.

    Remember flow is driven by pressure and density. The variations are small so the "push" driving the air out is small, so you need to have as little restriction to flow as possible.

    Wetting asbestos reduces dust to a minimum. Add a good mask and a wet and dry vacuum and you should be able to manage it. No doubt the safety police will lynch me for that, but remember my generation practically bathed in asbestos dust for half our lives.

    2c.
    I'm just a startled bunny in the headlights of life. L.J. Young.
    We live in a free country. We have freedom of choice. You can choose to agree with me, or you can choose to be wrong.
    Wait! No one told you your government was a sitcom?

  6. #6
    Join Date
    May 2007
    Location
    Blue Mountains
    Posts
    0

    Default

    We installed ceiling vents that can be closed. Its a 1 minute job every December and April to open / close them. Just make sure they are not so close to the eaves that the radiant heat send warm air down the vents.
    "We must never become callous. When we experience the conflicts ever more deeply we are living in truth. The quiet conscience is an invention of the devil." - Albert Schweizer

    My blog. http://theupanddownblog.blogspot.com

  7. #7
    Join Date
    Jan 2002
    Location
    Melbourne, Aus.
    Age
    71
    Posts
    0

    Default

    Yeah, what the roof is made of is key.

    Tiles will leak air and you don't need vents. This is my setup and I have 3 rotary ventilators.

    If you have iron, eaves vents are a good idea but get them installed by professionals if the soffits are AC sheet. There is no safe level of exposure to asbestos fibres.
    Cheers, Ern

Similar Threads

  1. sub floor ventilation
    By magnet 12 in forum FLOORING
    Replies: 2
    Last Post: 14th December 2005, 08:10 AM
  2. bathroom ventilation
    By jasonbrisbane in forum BATHROOM & TOILET
    Replies: 2
    Last Post: 30th August 2005, 11:52 AM

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •