Hi All,
Thinking of installing a whirlybird, just wanted to find out from those that have it, are they useful at all? Eg. would it help in cooling down the house during summer?
Saw on Bunnings website and the price range is from $69 to $126
https://www.bunnings.com.au/our-range/building-hardware/buil…
is there much of a difference between the cheapest one and the most expensive one?
He did the math!
That word is an abomination.
No, the correct word is 'maths'.
It is an abbreviation of 'mathematics'.
Only the Americans say 'math', because they corrupt everything to suit themselves.
He did the monster math!
elgrande if you have a newsletter I would like to subscribe to it.
I have a solar powered whirlybird and I find it has made a huge difference. It only runs when the roof space temperature is above 25degC.
The solar ones are so much better than the traditional whirlybirds. I've got 2. The battery backup means that they keep spinning when it's overcast and well into the night.
I went overkill and installed 4 in a single story home. Definitely noticed a decrease in heat.
Did you already have insulation?
Yes but the cheap kind from China about 5cm thick yellow colour. Only in the roof not walls as my house was built in the 1960s.
But I might replace the insulation one day with these:
https://www.bunnings.com.au/earthwool-r-6-0-275-x-430mm-5-49…
A few years ago I renovated my shed and added these in, and the temps have been pretty cool considering it has a metal roof.
Here are my current temps:
No AC are on currently.
Todays Weather | 33c
Google Reports | 24c Right Now
Weather Station Reports | 28.6c Outside
Indoor Temp | 22.2c with front door opened (Would be much cooler if door was closed but my dog wants to watch the cars)
EDIT: Should also mention that the room I'm currently in is carpeted.
A few years ago I renovated my shed and added these in
I am thinking of doing the same thing, mainly to keep my newly found doomsday preps in a cooler environment :D
Someone could make some money out of it in this climate! "Preparation Garage Conversions", corner off a section of a shed, add some shelving, a lock box, 6 pack of baked beans, 6x pack of toilet rolls and a whirlybird.
You need to build a special car viewing platform so your dog can sit on it and watch them through the window. :)
People say that you need at least 2 for them to be effective.
I have cathedral ceilings with no roof space, I'm thinking about installing a few as it gets really hot upstairs.
I had a cathedral ceiling and a partner that refused to have AC (I still have no idea why).
I installed an adjustable round vent in the wall at the roof peak with ducting to a whirlybird (it was a kit from bunnings). Closed in winter to retain heat, open in summer to ventilate. It did wonders.
vent was similar to:
https://www.bunnings.com.au/haron-international-200mm-round-…
Where did you mount the whirlybird? On the outside wall?
We have aircon downstairs but not upstairs and it gets really hot and I'm now working from home and sitting upsta so not looking forward to the heat of the next few months.
On top of the roof void adjacent to the room with the cathedral ceilings. Imagine that of the total roof space, only 1/3 was taken up by cathedral ceilings and the rest was a conventional roof void. It was a conventional mounting. I think if on the wall it would be too shadowed from the breeze to drive it and look like poo
There is no reason why you couldn't put the vent in the ceiling with a whirly bird directly above it and no ducting between the two.
@brad1-8tsi: Yes that is what I will probably do. There's only about 300mm between our ceiling and the metal roof with a little bit of insulation in between. I'd like to do it myself my the angle of the roof and also the height means I'll probably get someone else to risk their life to do it.
If you have no roof space, what space is the whirlybird going to vent?
Edit .. Brad just explained it
It's an "it depends".
If heat is being caught in a high spot as per comment re vaulted ceilings, it makes a lot of difference.
If you have a well designed house with a cross draft that vents out close to the ceiling it will make hardly any difference.
Do you have insulation in your roof cavity? It will keep the heat away much better than a whirlybird.
I lived in an old house with tile roof, no insulation. House was like a sauna. Then installed insulation, about 8cm thick, and the house because nice and cool during summer, but winters became a bit colder too :D
There is but it might be time to redo it.
Yeah useful. Not much sound. Get 2
This has been an on-going debate for eons and the evidence has been hard to find. The general consensus is that they will work but only if you install multiple units on your roof and have eaves vents installed also.
We had one installed almost 8 years ago now on a tiled roof with ceiling insulation. It "seemed" cooler in the house after coming back on a hot summer's day, but that may or may not have been placebo since it wasn't really measured in any way.
The nicer looking, more expensive ones also have higher quality, sealed bearings which won't end up drying out and making a whole lot of noise on the roof. You do get what you pay for with whirlybirds.
Given the chance to start over again, would I install a whirlybird? Probably not. Still not entirely convinced.
I'd add to this, that there's likely not much advantage on a tiled roof as there is already plenty of airgap to ventilate the roofspace through the tiles.
Having said that, removing a tile while working in the roofspace can help reduce temperature, or at least increase airflow, in the vicinity marginally.
Airgap? Only if you have no sarking under the tiles
I've being up in the roof space of alot of tiled roof's to install HVAC in summer and I can tell you right now they don't let any heat out, with or without sisalation installed. Once those tiles heat up they will just hold and radiate that heat into the roof space, the tiles get that hot you can't touch them.
Measured the temperatures a few times out of curiosity and got anything from 60-70°C during the peak of summer.
The ones that had whirlybirds installed had an obvious flow of air moving around and were noticeably cooler within the roof space.
actually when you go to roof during day time heat is trap inside and there is huge difference in temperature, also if you have aircon system ducting running through roof then your aircon heat get dispersed out within roof first then it hits your room so you loose lot in electricity and also aircon needs to work hard. My friend had same probleam and aircon guys request them to install on their roof and all aircon problem got resolved.
also many bathrooms exhaust are dispersed into roof cavity so moisture gets trap up in winter and develope condensation over period of time the insulation batton becomes a rock and loose the efficiency.
My old house had pink bat insulation, plus under tile sarking with the reflective side facing outwards and an open 500mm sq louvre in the roof peak. It was still shockingly hot which was detrimental to the goods being stored in there and also made an adjoining room very hot despite wall insulation (split level with cathedral ceilings).
I fitted 2 whirlybirds and 2 under-eave vents (these improve the overall air flow a lot) . The heat difference was amazing with the added benefit that the roof space had less condensation.
If you fit the clear whirlybirds it also deters some vermin and insects.
Negatives:
I think it draws in more dust
Only works when there is breeze although hot air will still escape due to the thermosyphon (whatever it's called - hot air naturally rises) effect. I'd get a solar powered unit next time.
If you do a bit of research there are a few websites that provide the details of how to calculate the amount of air movement required for the extractors to be at peak efficiency.
Basically, you need to work out the volume of air in the ceiling/roof cavity and using the air flow of the extractor it can be determined the hot air removal per hour.
We are looking at getting one of these or similar. They work more effectively than whirlybirds.
Do most houses have a well-sealed ceiling cavity? In my experience with tiled roofs there is always so much air gap that it wouldn't be possible to draw cool air into your roof. You would only be moving some air directly around the whirlybird.
And roof tiles themselves have such a huge thermal mass that on a hot day you would need a high pressure blower to begin to make a difference. not a exhaust fan spun lazily by the breeze.
If you were working in a roof and removed some tiles to let some air move around I'm sure it would feel much cooler to a person (because of air movement) but not actually cool the cavity enough to stop heat penetrating down through your ceiling.
Can confirm… Working in the immediate vicinity of a removed tile feels cooler, but go anywhere more than ~1m radius and there's no discernable difference.
I thought you meant a helicopter landing pad for the roof for some reason. Was like, I guess its useful if you really need to get somewhere fast and you have money to burn, though parking will be a pain.
I installed a couple on the roof a few years ago. The one thing that struck me the most was when I removed one roof tile and was standing next to the hole the air gushing out was incredibly hot. Getting that hot air out of my roof space lowered the indoor temp by at least 6 or 8 degrees on a summers day.
Actually, I can try this on weekend. Remove a tile and see how hot it is in there.
I was standing on the roof and every time I put my face near the hole it felt like a strong breeze blowing on me.
We installed a Bradford Airomatic on our roof.
Its mechanicaly driven (doesnt rely on wind).
You can set the speed manually or have it on auto which will maintain the temp at or below 25c.
Definately makes a difference. Our AC also doesnt have to work as hard as the ducting in the roof doesnt get heat-soaked.
Whirly birds are used to reduce the temp of the roof space, this reduces heat.
I also have Bradford yellow batts (to reduce the ceiling heat transference for my a.c. so it works better) working very well, I didn't have a heat wave lol.
In Tasmania where it doesn't ever get that hot, we have a heat transfer unit in the roof to take residual heat into the house. So clearly you would want the temperature to go up when the sun shines in winter (most of the year!), but my partner has a whirly thing on the roof… im all for removing it in our case.
She got it thinking it would reduce humidity and condensation and hence mould in the house and for some reason people told her it would. Maybe temp differential causes more condensation on the ceiling. Anyways, easier to leave it on the roof.
Is your roof tile or sheet metal?
The device simply sucks out air form your roof cavity.
You may be sucking out cool air and sucking in the outer hot, if you install.
Pink Bats should be doing their job
Tiled roof.
We've got a tin roof and it does get pretty warm in the roof space over summer… we have 2 whirly birds on the roof and this is the coolest house we've ever lived in over summers (weatherboard too). We've been here for 2 years and bought it this way so can't compare no whirly to whirly, but they run pretty quick during hot days so I assume they do a good job.
Would this be good for metal roof and bathroom exhausts (with no ducts)?
$57