roof ventilators ( house )

[waynep]

i've bought a couple of those whirly gig roof extractors to put on the house roof and try and vent the roof space and keep the inside house temps down over summer.

Just wondering if anyone has any advice on where to position these on the roof. Its an L-shaped house with tile roof ( non sarked )

I also bought a couple of the ceiling vents ( ones you can open and shut ) . .where should i put these in relation to the roof extractors .....ie right under them or across ways a bit ?

we don't have aircon at the moment just seeing if these ventilators and sun blinds keep the house cool enough to avoid installing it.

[Blknight.aus]

the ventilators go up near the ridge line about equidistant from the ends and each other.

but the vents are going to be a bit of a conspiracy theory....

do you want them in the house sucking the air out of it and drawing fresh but hotter air into the house OR do you want to put them in the eves outside so that the air can circulate in the roof space leaving the air in the house untouched save for what gets drawn in via the kitchen extractor and toilet/bathroom roof vents?

I like the latter idea ESP when it comes to heating in winter.

[4bee]

What Dave said. Bung the vents into the eaves.

Fans flash under the ridge capping. Vent the roof space only.

[101RRS]

Do they work though.

The ones bunnings sell just have the whirly thing - I was told the logic is that the wind turns the whirly bit that creates a vacuum that in turns sucks out the hot air - but I would have thought the wind entering the whirly bit would have filled any vaccum and the hot air would stay put.

I have seen some that have a fan connected to the whirly bit so that the wind is driving the fan which extracts the hot air - Bunning models cost about $80 but the ones with the fans are closer to $200.

I am interested in this because my house is a hot house - normally getting hotter than the outside air in summer - is a high house, lots of glass and faces west.

Garry

[4bee]

Gazza. Air in (eaves) = Air out (vent).

The hot air flowing through also spins the vanes as does a very light breeze. In fact, even when I cannot see the leaves moving, the vent is spinning away.
Seems to work for me but I really do need more inlet air (problem ex- motor garage/ now garden room roof.)


http://www.laserlite.com.au/residential/vents/spinawayMK2.asp




http://www.laserlite.com.au/commercial/alsyniteIndvent.asp

[Blknight.aus]

the simple ones work, I put 2 in the house in townsville and providing I remembered to keep the downstairs part closed up it dropped the house tmep 3 degrees And I could work in the main roofspace during the day if i really needed to.

they work paritally on centrifical force, partly on vortex dynamics and partly on hot air rising.

on a day with dead still air you will see new ones (or well maintained old ones) slowly turning from the hot air venting out of them they are essentially at this point just an opening in the roof.

when they are spinning from external wind the downwind side of them develops a vortex (like the back of a landie on a dusty road) that sucks the air out of the whirly gig (anyone who points out the whole no such thing as sucking gets a free set of curses and an addition to my "things I hate" list)

and when they are spinning the air inside them is centrifuged towards the outside and then out the vent slots.

Heres something fun....

If you look at one of the cheap ones(call it $80 as previosly mentioned) and then one of the expensive ones($200) you will notice that aside from the addition of a metal or plastic fan in the middle of the shaft that supports the whirly gig spinnery bit they are identical... and all that holds it together is a metal shaft 2 support bearings a couple of washers and about a 10mm nut...

If you goto the tip/junkyard/recyc shop you will find lots of extractor fans (the ones that go in the ceiling for your bathroom/toilet/kitchen) that have a plastic fan on them.. Find one with the same shaft diameter as your whirly gig, pay the man $5 for a burnt out one then go home and dissasemble both the whirly gig and the extrator fan. Drill the mounting spigot for the fan all the way through with the same size drill as your whirly gig shaft then assemble the fan onto the whirly gig (pay attention to fan orientation here) secure in place with some 2 part epoxy, the little mounting grub screw or some loctite bearing lock.

you now have an $85 whirleygig that is more or less exactly the same as a $200 whirly gig.

If you put a pully on in place of the little nut at the bottom (use a thrust washer and a grubscrew located pully) you can attach a small 12v stepper motor with a pair of blocking diodes and a capacitor that will happily charge a 6v gel cell battery that is more than capable of running LED lights in the ceiling as emergancy lighting for when the power goes out (or when you blow the bulb in your work light while your up there)

[JohnE]

Aside from the fiddly stuff just just talked about, I am on my second set of ventilators, the only difference was i wanted to maximise the eave vents so I have 6 coming from the back through a skillion roof to a pitched roof and out.
just had the roof replaced , corrugated zincalume, on top of sisalation, to date the house is 10 deg cooler than before,a lot easier on the A/c's
i only put the new spinners in last week.
the easiest way to test the draw, from the eave vents is to go to your manhole on a warm day and open it up, you should get a sudden instant rush of air straight past you and into the roof.

I wouldn;t use the in room ventilators, because as BK said, what goes through them must come from somewhere and outside air is the obvious place, trying to get rid of heated air and replacing it with heated air defeats the reason for having them.

the electric, thermostat controlled ones, with the fan, I think they are called the 'thinking cap' use electricity and have to be wired, the others spin with or without wind.


john

[loanrangie]

I'm thinking about a couple of them as well, after yesterday then todays heat our house is like a sauna and we only just got our 7 mnth old to sleep after first trying at about 7.30. Also looking into evaporative cooling as the little box aircon unit does squat. Our eaves are fully enclosed so maybe some vents spaced around the house would also help.

[waynep]

Thanks for the replies guys, much appreciated ... I knew ther'ed be a wealth of knowledge on this.... us LR owners like "alternative" solutions to things ....
a lot to read through there I'll have to print it out and go through it all. ;)

couple more questions leading from your comments :

1. these are the type of extractors I have bought http://www.edmonds.com.au/html/products/supavent_turbine_ventilator_250mm.htm
the instructions say if you have a non-sarked tile roof there is no need to put the vents in the eaves because enough air comes through the gaps in the tiles. Is that true ?

2. we have downstairs a double brick basement that is hafl undergound and stays really cool in the summer ( in fact we sleep down there when it gets really hot. :D). My theory in putting in the ceiling vents was to perhaps draw some of the cooler air from downstairs in to the main living area upstairs. Would that work ?

3. Our upstairs is brick veneer. The inside plaster has the wall vents up near the ceiling. Now I heard that those vents actually let hot air in from the space between the bricks and the plaster, and you can now legally block them up. Is that true ?

[4bee]

My theory in putting in the ceiling vents was to perhaps draw some of the cooler air from downstairs in to the main living area upstairs. Would that work ?

Wayne, to me that would be a bad move as you will then heat up your cool oasis which will then need to cool down again. While that is happening, assuming that the weather doesn't get hotter, you won't have the benefit of the Oasis.

It will also depend on whether soil behind the walls is up against the walls (unlikely) or open as a vented to outside & therefore ambient temperature storage area.

[George130]

They do work. I fitted one 2 years ago to our tin roof house. Tiles are easy as it just replaces the tiles so there is no cutting. I would set it up to only vet the roof space.

[loanrangie]

Thanks for the replies guys, much appreciated ... I knew ther'ed be a wealth of knowledge on this.... us LR owners like "alternative" solutions to things ....
a lot to read through there I'll have to print it out and go through it all. ;)

couple more questions leading from your comments :

1. these are the type of extractors I have bought http://www.edmonds.com.au/html/products/supavent_turbine_ventilator_250mm.htm
the instructions say if you have a non-sarked tile roof there is no need to put the vents in the eaves because enough air comes through the gaps in the tiles. Is that true ?

2. we have downstairs a double brick basement that is hafl undergound and stays really cool in the summer ( in fact we sleep down there when it gets really hot. :D). My theory in putting in the ceiling vents was to perhaps draw some of the cooler air from downstairs in to the main living area upstairs. Would that work ?

3. Our upstairs is brick veneer. The inside plaster has the wall vents up near the ceiling. Now I heard that those vents actually let hot air in from the space between the bricks and the plaster, and you can now legally block them up. Is that true ?

Wayne, this house sounds like it has the same layout as ours, 3 b/rooms upstairs with a spare room and luandry downstairs, we also sleep downstairs if its too hot upstairs. In regards to tiles, what does sarked mean ?

[waynep]

Wayne, this house sounds like it has the same layout as ours, 3 b/rooms upstairs with a spare room and luandry downstairs, we also sleep downstairs if its too hot upstairs. In regards to tiles, what does sarked mean ?

I'm no builder but I beleive sarking is the stuff they put directly under the tiles. It used to be a bitumeous paper but these days its more like a aluminium coated paper. I believe it is supposed to stop the condensation from the tiles dripping on to the ceiling ? Any roofers / builders on here will correct me I'm sure. As far as the ventilation part goes, if you've got sarking then no air can flow in between the tiles and out through the ventilators, therefore you need to install vents under the eaves.

Yes your place sounds exactly like our setup.

[RonMcGr]

i've bought a couple of those whirly gig roof extractors to put on the house roof and try and vent the roof space and keep the inside house temps down over summer.

Just wondering if anyone has any advice on where to position these on the roof. Its an L-shaped house with tile roof ( non sarked )

I also bought a couple of the ceiling vents ( ones you can open and shut ) . .where should i put these in relation to the roof extractors .....ie right under them or across ways a bit ?

we don't have aircon at the moment just seeing if these ventilators and sun blinds keep the house cool enough to avoid installing it.

I have four of them, evenly spaced out accross the ridge line of the roof.
I also have about 10 airvents in the eaves so the hot air is drawn out of the roof cavity. On top of that, the top of the ceiling is also covered with "space age foil" (bubble wrap with silver on either side).

The result, roof cavity is a lot cooler, house is a hell of a lot cooler in summer and TOO cool in winter. :eek:

[waynep]

Wayne, to me that would be a bad move as you will then heat up your cool oasis which will then need to cool down again. While that is happening, assuming that the weather doesn't get hotter, you won't have the benefit of the Oasis.

It will also depend on whether soil behind the walls is up against the walls (unlikely) or open as a vented to outside & therefore ambient temperature storage area.

Hmmm good point.

so it looks like I need the eave vents then ...gotta get some of those.

I think i'll still install the 3 internal ceiling vents /registers I bought, then I can open them up in the evening to assist with cooling down of the house ( venting the hot air up through the roof )

..gonna be interesting ti see how much difference this makes ... i'll report back.

[loanrangie]

I will be fitting a couple of whirly gigs next weekend as well, i dont have anything under the tiles at all but i think a few well spaced vents in the eaves will help. I have rolls of insulation foil that i thought of stapling to the under side of the roof bearers.

[4bee]

i think i'll still install the 3 internal ceiling vents /registers i bought, then i can open them up in the evening to assist with cooling down of the house ( venting the hot air up through the roof )It just shows there ain't nothing new in the world.

You just reminded me, Wayne.

Back in the days of olde when I did my Refrigeration Apprenticeship (& later Air Cond) I purchased an Audels Refrigeration & Air conditioning Guide AKA 'The Bible', & not because it just looks like one either.:D

In it, it describes the design & installation of "Attic Fans". (USA 1949)

In a 2 storey house there was located in the upstairs ceiling, a couple of grilles open to the living area. Connected to those by ductwork was an electric motor driven centrifugal fan.

The plan was that as the evening ambient temperatures outside fell, one opened all the windows in the house & fresh, & supposedly cool air was drawn through all night.

Come daybreak, the windows were shut & windows closed. Repeat nightly as necessary. :D



Btw, if you want to know how to air condition a Pullman Railway Car or build a cork insulated Butcher's Ice Box or air condition your Cargo Ship, let me know. I'm your man.



Dunno why the Caps haven't worked. ?????????

[JamesH]

I've wondered about roof vents myself. Is there a way in winter that you can shutdown the whirly doover or close off the exit hole.

They'd help you'd save cooling costs in summer but you would not want them to increase heating costs?

[4bee]

Yes, you could do what they do with Evap Coolers. Tie a plastic cover or UV plastic bag over them.

When I first mentioned this the bloke said all he did was put a long screw through it to stop it rotating. :confused:

But I think you would still want them to ventilate the roof space ONLY, in Winter, as Kitchen & Bathroom exhaust fans normally discharge into the roof space & they would assist in reducing the build up of excess moisture.

[Tote]

It just shows there ain't nothing new in the world.

You just reminded me, Wayne.

Back in the days of olde when I did my Refrigeration Apprenticeship (& later Air Cond) I purchased an Audels Refrigeration & Air conditioning Guide AKA 'The Bible', & not because it just looks like one either.:D

In it, it describes the design & installation of "Attic Fans". (USA 1949)

In a 2 storey house there was located in the upstairs ceiling, a couple of grilles open to the living area. Connected to those by ductwork was an electric motor driven centrifugal fan.

The plan was that as the evening ambient temperatures outside fell, one opened all the windows in the house & fresh, & supposedly cool air was drawn through all night.

Come daybreak, the windows were shut & windows closed. Repeat nightly as necessary. :D



Btw, if you want to know how to air condition a Pullman Railway Car or build a cork insulated Butcher's Ice Box or air condition your Cargo Ship, let me know. I'm your man.



Dunno why the Caps haven't worked. ?????????

The Lands department building in Bourke, built in 1898 was also designed on such a principal, there were vents in the floor that pulled cool air from the under floor area and distributed it inside the building.
Regards,
Tote

[waynep]

Yes, you could do what they do with Evap Coolers. Tie a plastic cover or UV plastic bag over them.

When I first mentioned this the bloke said all he did was put a long screw through it to stop it rotating. :confused:

But I think you would still want them to ventilate the roof space ONLY, in Winter, as Kitchen & Bathroom exhaust fans normally discharge into the roof space & they would assist in reducing the build up of excess moisture.

Yes from my reading ventilators do provide benefit in winter too.
On that subject, this is interesting
http://www.condorvent.com.au/comparison.html

The guy's theory is that the "whirly-gig" ventilators ar primarily a "winter" device and his inert design works much better in cooling houses in summer -
maybe i bought the wrong thing oh well - might need to try Blknightts "mod" and put a fan in them.

[4bee]

https://www.aulro.com/afvb/images/imported/2007/10/126.jpg

Tote. Slightly OT
When I was doing Refrigeration Maintenance I did a run every couple of months through the country & this old Farmer's Union Cheese factory on the Western shore of Lake Alexandrina at Milang, was one of the places I visited.

Under the road in the foreground is a brick/stone tunnel that starts in the storage area & finishes up in a steel grille on the bank of the lake.

The lake breezes flowed through this & cooled the cheese rounds in the store.

I think the grille is blocked now, but I will reinvestigate this week when I take a drive there to see just how much the poor old lake has dropped. It didn't look good last photo I saw.

lanyfromanutherland may also be interested.

[4bee]

Lake Alexandrina a couple of years ago. It's much lower now.:(


https://www.aulro.com/afvb/images/imported/2007/10/125.jpg

[Blknight.aus]

a hand full of things...

1. industrial rolls of alfoil make excellent under tile insulation when backed with the cheapy rolls of speaker padding insulation alfoil to the tiles and then staple the insulation tightly under them on the supporting timbers

2. you can get a winged butterfly that attaches to the bottom of the whily gigs and has a pull cable on it, route the cable and extend as required to your man hole and come winter you can just release the cables and the butterfly springs back... (assuming you dont let them rust...

3. when you put them in put walk boards onto your main trusses so you can get to them easily for a few reasons

We had birds trying to nest in one of ours so had to crawl the space to get to them

when the bearings develop a squeek they will drive you insane as the squeek does not remain constant so its hard to tune out.

ditto for when you get a bird strike on one and it gets a ding that makes it scrape and stick.

since youve put walkboards in you can now start extending them and using the roof space to store shoebox sized boxes of stuff you want to keep cleanish and dry and out of harms (or prying eyes) way

[JohnE]

I'm no builder but I beleive sarking is the stuff they put directly under the tiles. It used to be a bitumeous paper but these days its more like a aluminium coated paper. I believe it is supposed to stop the condensation from the tiles dripping on to the ceiling ? Any roofers / builders on here will correct me I'm sure. As far as the ventilation part goes, if you've got sarking then no air can flow in between the tiles and out through the ventilators, therefore you need to install vents under the eaves.

Yes your place sounds exactly like our setup.


on newer houses they don't sark unless you request it, it used to be mandatory for tiles because they can chip with time and crack.

the more modern stuff has thermal qualities

here

http://www.insulationsolutions.com.au/pdf/Sisalation-438.pdf

with the roof ventilators you need to be able to replace the air in the roof cavity, as it heats up on a hot day and doesn;t go anywhere, the gap in tiles is not enough to give you a full cycle of air movement. eave vents are, remember the hot air rises principle.
If you are a closet smoker, once you have installed eave vents, just put a lighted cigarette under each one, if all is working correctly the smoke should be drawn up.


john

[waynep]

Well that was easy :D

... I installed the two whirlygigs and the eave vents on Saturday all in about 3 hours.

...they were really spinning on Sunday with all the wind. :o

[jx2mad]

In my past life I spent a lot of time in roof spaces. I am amazed that tile roofs that do not have sarking are actually waterproof. If you look around you see daylight through most tile joints (between rows), so the provision of vents in the gable ends is almost superfluous. Jim

[PhilipA]

I have half done mine in that I have put in eave vents and am "gunna" put in the whirlygig I have had lying in the garage for a couple of years.

Even the eave vents increase air circulation greatly . On a windy day you can feel the flow from the downwind side.

My plan is to get a closable vent for the manhole cover , or just get another piece of fibre cement and bore lots of holes, and to put a matching vent inside the linen cupboard to draw cool air from under the house. Then close them off in winter.
However SWMBO always objects when I go to get on the roof even to fix broken tiles( of which I have lots due to my overhanging Gums).
Anyone know where I can source a closable vent to fit in a manhole cover? I have tried Bunnings etc and on line but no luck.
Regard sPhilip A

[4bee]

Try an AC Contractor who specialises in Evaporative Coolers as that is about the size diffuser you are talking.
You can get manually closed blades in the segments or you could fit a diffuser box over the neck & control it remotely with a motorised Damper. No ladders etc.