# Forum Home Renovation Bathrooms  where do range hood exhaust goto?

## wozzzzza

i have a rangehood i need to install in my kitchen, but what i want to know is where do i extract the exhaust to??  does it just go straight into the roof or does it go elsewhere?
if it just goes intot he roof, wont it mess the roof up and make it all greasy and oily after a while??

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## Sybarite

Illegal and dangerous to vent a hood into a roof space. 
Your range needs to exhaust to the outside via ducting through either your wall or through the ceiling and roof. 
There are lots of special kits available to do this, but a good tip is to use straight pipe rather than concertina tube where you can. 
Cheers, 
Earl

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## wozzzzza

ok, so straight through the ceiling past the roof into the atmosphere? so there will be a pipe sticking out of my roof afterwards then with a cap on it like on top of chimneys for fireplaces??

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## cabman

did my range hood awhile ago just bought some fexilable duct from bunnings from the rangehood to outside under neath my eve and just bought a vent to put over the duct very easy all up i think it cost my $70 with the vent cheers

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## Kanga

> Illegal and dangerous to vent a hood into a roof space. 
> Your range needs to exhaust to the outside via ducting through either your wall or through the ceiling and roof. 
> There are lots of special kits available to do this, but a good tip is to use straight pipe rather than concertina tube where you can. 
> Cheers, 
> Earl

  Earl 
Did you not see that wozzzzza is in South Australia.
Your statement ONLY applies if he lives where you do.
It is NOT illegal nor dangerous in South Australia to vent into the ceiling space 
Reason being we dont have high humidity here like in Qld. 
Insurance company in Qld insist on venting rangehoods into the attmosphere. 
Flexable ductwork creates resistance and slowes down the air flow.
Straight, smooth sided ducting is best if possible

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## Sybarite

> Earl 
> Did you not see that wozzzzza is in South Australia.
> Your statement ONLY applies if he lives where you do.
> It is NOT illegal nor dangerous in South Australia to vent into the ceiling space 
> Reason being we dont have high humidity here like in Qld.

  How about that Kevin? 
You are correct that I assumed these restrictions were nationwide - I always thought that the restrictions on venting into roofspaces had to do with rangehoods exhausting greases that will eventually settle around the vent in the cavity and pose a fire hazard...never knew it had anything to do with humidity! 
I would still recommend venting to the atmosphere regardless. 
And once again, another good reason for avoiding concertina pipe if you can. 
Cheers, 
Earl

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## davo2310

agree with not using flexible ducting for range hood, especially if you dont want rats chewing through it.

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## Kanga

> How about that Kevin? 
> You are correct that I assumed these restrictions were nationwide - I always thought that the restrictions on venting into roofspaces had to do with rangehoods exhausting greases that will eventually settle around the vent in the cavity and pose a fire hazard...never knew it had anything to do with humidity! 
> I would still recommend venting to the atmosphere regardless. 
> And once again, another good reason for avoiding concertina pipe if you can. 
> Cheers, 
> Earl

  Earl
You are correct in the fact that grease will pose a fire risk if they settle around the vent in the cavity.
With a decent rangehood and regularly cleaned filter(s) grease should NEVER be able to get into the flue in the first place.  
This is why the filters need to be kept clean.
There is a bigger fire risk from greasy filters and gas cooktops than most people  
realize. 
This is why it is necessary to clean the filter regularly. 
As far as humidity goes, this is a ruling by the insurance companys here in South Australia.
Venting into the atmosophere just adds another point for water to leak in.

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## Buggermedumplings

Depends on your rangehood too- Check the specs as you do not want to undersize the pipe.  Our single motor Qasair needed 200mm solid ducting as a minimum.  Kanga is right too, if the filters are doing their job, grease shouldn't be an issue.

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## Kanga

> Depends on your rangehood too- Check the specs as you do not want to undersize the pipe. Our single motor Qasair needed 200mm solid ducting as a minimum. Kanga is right too, if the filters are doing their job, grease shouldn't be an issue.

  I"ve seen the Qasair brand ,they seems to be very efficient rangehoods.
I think they also make twin motor models as well

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## zx9

Hi, 
I 'm in the process of designing my kitchen for a townhouse. unfortuntly the exhaust duct for the range hood has to go up across the ceiling then turn & up the wall of the second level to the roof. this will mean a very long exhaust duct with at least 3 90 degree bends. is this ok? it doesn't sound ideal but i dont have many options?

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## Buggermedumplings

> I"ve seen the Qasair brand ,they seems to be very efficient rangehoods.
> I think they also make twin motor models as well

  Efficient and quiet.  They do make twin and even triple motor versions of nearly all models- very pricy though.  Single motor versions push 950m3/hr which is plenty, if you were doing a lot of wok/asian style cooking then you could fork out for the twin.

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## Kanga

> Hi, 
> I 'm in the process of designing my kitchen for a townhouse. unfortuntly the exhaust duct for the range hood has to go up across the ceiling then turn & up the wall of the second level to the roof. this will mean a very long exhaust duct with at least 3 90 degree bends. is this ok? it doesn't sound ideal but i dont have many options?

  There are two other possibilitys here
You _might_ be able to vent out horizontilty through a wall instead of going vertical. This will save a few bends, and make for a more efficient air flow.
The other method worth considering, recirculated rangehood with a charcol filter.
No ducting required at all. just change a filter every so often.
Of course the downside is you don't get rid of the  cooking heat this way.

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## Metung

I can't help but think that regulations mentioned with regard to range hoods is nothing more than over regulation. If any of the concerns referred to were of any real consequence then it seems to me that there should be a regulation ensuring that the cook top will not operate unless the rangehood is operating.  
I agree with Kanga, and I am most reluctant to cut a hole in an external wall, which is the only option, to vent a ground floor rangehood that will be seldom used . At the moment it will be going up through and to the top of the overhead cupboard, with another filter at the top.  
I'll be having the inspection for the certificate of occupancy soon so it could be interesting.  :Rolleyes:

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## Just George

> i have a rangehood i need to install in my kitchen, but what i want to know is where do i extract the exhaust to?? does it just go straight into the roof or does it go elsewhere?
> if it just goes intot he roof, wont it mess the roof up and make it all greasy and oily after a while??

  
What Earl says in your first reply is correct. Having said this, if your rangehood is working correctly, it should remove all moisture and oil.

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## chuth77

> Earl 
> Did you not see that wozzzzza is in South Australia.
> Your statement ONLY applies if he lives where you do.
> It is NOT illegal nor dangerous in South Australia to vent into the ceiling space 
> Reason being we dont have high humidity here like in Qld. 
> Insurance company in Qld insist on venting rangehoods into the attmosphere.

  Your last statement says it all... Insurance... But I don't think it's just insurance asking for it, I thought it was part of the BCA now in that any exhausting to ceiling spaces of moisture was not allowed... 
It's got nothing to do with humidity, but rather exhausting cooking gases and the resulting oil into you ceiling space is huge fire risk.. Ever seen what the exhaust looks like after 12 months of cooking...

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## Bloss

National regulations (BCA) specify various installation parameters for range hoods such as the heights from the cooking surface to the bottom of the hood. 
There are vented and unvented hoods - operations of both are governed by Australian standards on electrical and/or gas appliances (which for example mandate certain filter types for recirculating systems etc). 
If hoods are ventilating then they must be to the outside and in most states that venting must be installed by a licensed contractor (mostly a plumber). 
In almost all local government areas there are rules about venting any material to the air and especially relating to combustible materials (such as oil and fat fumes) from exhaust vents (often based on OH&S issues). Although moisture build-up from in bathroom vents and oil and dust in kitchens are a concern over time the biggest issue is fire safety. 
Stove-top fires are one of the most common causes of house fires in Australia. It takes little to imagine what happens when a fan above stove draws the flames from a oil/ fat fire directly into the roof space even if through the metal mesh filters commonly used. 
As has been said the pipe work should be metal and as straight as possible one 90 degree bend will reduce efficiency by around 35% and each additional bend by around 20% or so and that is assuming that the pipe size is correct for the outlet and the flow capacity of the fan.   
In your situation I reckon you should probably just get a non-venting recirculating type which have charcoal filters to remove odours, in addition to the metal mesh fire resistant ones.

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## wozzzzza

this is what im gonna do, ive found a venting kit for $165, bloody ripoff, so i thought stuff it, create my own,, i can get the 1.8m metal pipe needed for $13.90, flashing for $10, and make the cowl my self for $8 totalling about $32 saving me $133.
it will stick out the roof and be safe.

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## Bloss

Good choice - save your self some pain though by using a suitable flashing kit such as those from Dektite - http://www.deks.com.au/flashing.htm. 
 I assume you have gal iron roof so you just need to cut a hole then place the pipe through flashing over the top (has neoprene seal)tap lead into corrugations lift around edges and silicone (with proper roofing sealant) tap back into place and you are done.

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## wozzzzza

no, tiled roof.

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