Hi all, you probably heard of solar roof ventilator. Do they actually work in term of bringing down inner roof temperature?
Came across brand like Solarstar, Broan etc…If they work, any brand I should go for?
Looking for recommendation for installers in Perth
Thanks!
I got one from Masters with a nice discount, I regret not getting more. I have ducted mine to a room that had poor air movement, problem solved.
I fitted mine under the ridge cap so I didn't have any leak issues.
Hi,
Got 2 passive whirly birds plus 4 eave vents, all north (sun) facing.
I also got a remote thermometer in the rough.
The roof temperature is hardly a few degrees above outside temp even in summer.
In conjunction with a decent ceiling insulation it works great.
With solar fans only really works with sun, not really when warm and cloudy, also solar panels age.
For me the passive solution is quite effective, no need for costly solar fans.
Cheers
I seen first hand the airflow of whirly bird.. Literally non existent though..no offence but it feels a bit like useless with traditional whirly birds.
I also got a remote thermometer in the rough.
You live on a golf course?
If you're doing it to cool the roof space cause you hang out there a lot, then I can understand the logic, but if you're doing it with the aim to improve cooling of your living spaces, I don't really see the point.
Not convinced that the roof cavity temperature impacts the room temperature much, if at all.
I used my thermal camera to check difference between areas where I have roof insulation and those which don't (few small parts). There is a noticeable difference in heat radiating.
In my opinion good roof ventilation keeps the roof dry, cooler and and in combination with decent roof insulation definitely also avoids heat radiating from the roof into the rooms underneath,
I'm more than happy to be corrected… but nobody EVER that I have seen has provided any actual evidence.
What was the exact "noticeable difference" that you measured with your camera (I'm happy to accept uncalibrated thermometer data)?
And how is this a valid test of the efficacy of roof ventilation?
It provides evidence that Roof insulation reduces radiation and nothing more that I can see.
Even then, testing different areas is not particularly scientific. The majority of difference might just be caused by the pitch of the roof bringing the hot roof closer to the uninsulated ceiling… Therefore more radiation from the roof directly hitting the un-insulated ceiling.
I'd accept a test of blocking up ventilators and testing a marked spot of the ceiling (not roof - although that'd be interesting) temp and room temp with an IR thermometer/thermal camera at a specified time of day (say Mid-day) on a cloud free day.
Then unblocking the vents to let the roofspace cool overnight and testing again on the following day at the same testing time with very similar outdoor temp and on a similarly cloud free day.
If there was more than a 1 degree difference, in ceiling temp, I'd rate that as different, but unlikley to be noticeable unless room temp was similarly different and on the fringes of reliability.
2 degrees difference in ceiling temp should be outside the error margin of the IR thermometer (not sure about thermal camera accuracy) and might result in a measurable difference in room temp.
Might even try this myself one day…
Just remove a few tiles and leave the manhole open to provide some airflow.
Would also be interested to know what sort of roof you have..
Steel roof, would have less ventilation than a tiled roof for example.
Suggest you do the test to your exacting standards, let us know how you go and makes sure you do it properly.
I am happy with my setup and its effectiveness to my standards.
If anything, they're less than the basic requirements to actually test the hypothesis. A proper test would be done across more than 2 measurement days and would include measurements of ambient, room and roof space temperatures as well as wind strength and direction.
Are you happy to share your data at least?
And what type roof you have?
Temperatures in a roof cavity can be very high. (I've measured temperatures in the 60s) This heat is going to get through the ceiling into your living areas. Of course ceiling insulation will help but it is best to get rid of as much of the "source" heat as possible.
A powered extraction fan is the best option (in combination with eave vents to give a flow path otherwise your fan is going to try and create a vacuum with no actual airflow).
"Wind powered" extractors are not serious movers but they do give you a vent in the roof through which the heat can exit, but not in any large volumes.
Solar powered fans are better but the manufacturers do not seem to specify the key parameter of cubic meters of air moved per hour (because this will depend so much on sun and installation and site factors). They will not have the same effectiveness of a more powerful mains powered extractor fan where the cubic meters per hour are specified.
This heat is going to get through the ceiling into your living areas
How?
Gyprock isn't exactly the greatest conductor or radiator of heat and radiation is the only way heat is going to get from your roof cavity into your home.
Convection will only heat your roof space.
RobMel above reckons he has seen some data on the conduction of heat through Gyprock albeit flawed data comparing insulated against non-insulated Gyprock.
Gyprock is a very poor insulator. With R ratings, the higher the better, but here are Gyprock's own figures
Thermal Performance - R Values, 0.05 – 0.07 m2K/W, 0.07 – 0.09 m2K/W.
So, without insulation, that ceiling cavity heat is going to be readily conducted into your rooms beneath.
On the other hand, with current cold weather on south east coast, I want my roof and ceiling to be warm and radiate any heat to the house. What's the best balance of insulation and ventilation in the roof to achieve heat retention in winter and minimising heat in summer?
There's a thermostat option.
Your extremes are such that there is no acceptable compromise. You need to have a completely different solution for summer and winter but in each case you need very effective insulation.
Movement of warm air needs appropriate temperature monitoring and intelligence and control to send it to the most appropriate destination.
But this is a very common scenario. What do people in say Melbourne do? They have very cold winters and very hot summers.
Block up your Eave and roof ventilators in Winter so you do generate some extra heat in the roofspace.
You'd then need either a heat exchanger to pull the heat from the roof down into the house or a filtration system to clean and suck the air from the roof space into your house.
The second method is probably cheaper, but you need a vent to push out the cold air without allowing cold air back in again (ie at night).
The other problem of course is that the roofspace doesn't get all that warm in Winter.
You're probably better installing a closed loop Solar Hot water system and running a heat exchanger off that!
I did a LOT of research before choosing an Edmonds Airomatic a few years ago, and so far it has performed really well and has made a big difference! It's the equivalent of about 6 whirlybirds. The fan is really powerful, if you go onto the roof and put your hand under it you can feel it blowing air hard on a hot day.
Automatically adjusts speed based on the roof temp, so at night it turns off completely.
It is a plug in powered roof vent, so it works even in winter to remove moist air. You need a normal power outlet in your roof to plug it into.
Before we installed ours, our ducted air con would not cool the house if the temp reached 35 degrees. Roof was too hot and it couldn't cope. Now it cools even at 40 degrees or more, it has made a huge difference.
Get them at bunnings on special order, i think i paid about 200 bucks.
https://www.edmonds.com.au/home-ventilation/roof-space/airom…
I didn't bother with eave vents in the end because it worked well enough without them, and tiles / bathroom fan seem to allow enough air in.
We installed a Solarking Yesterday, It works fantastic the fan helps to take the heat out of the roof.
Hey, I know it was 10 months ago but how is the Solarking performing? I'm looking into them & how much did it cost?
SolarKing installed here this time last year as part of major roof restoration (old tiles and battens removed, insulation sarking fitted, new battens, new tiles). 2 existing whirlybirds reused (after bearing replacement and repainting) at either end of the house and SolarKing in the middle. Placed about 10 under eave vents all round to help with circulation. The thing is fairly noisy when it's bright and sunny but it does the job in keeping the temperature down. House was an oven on hot days prior to the restoration work, a lot more comfortable now.
Can't tell you the price of the SK, as it was incorporated into the roof tile job.
If you're considering fitting one, try and fit some eave vents as well to help with circulation. We used these, they're pretty cheap and easy to fit.
Thanks so much! Mega helpful -
https://www.ozbargain.com.au/node/274810
still undecided