# Forum Home Renovation Heating & Cooling  Rangehood vent to outside. How?

## N0mad

We have bought a Robinhood 90cm rangehood for our new kitchen and we want it to expel the air outside. This is a link to the hood  :Biggrin: . http://www.robinhood.com.au/products...00_Wall_Canopy
The plumber promptly said that he had never connected a rangehood to evacuate air to the outside of a house before and could I help with advice on this!!!  :Doh: 
Does anyone know how this should be done? Should we connect it to a "Witches hat" or to a hole in the eave (both suggested in the rangehood installation instructions). Can't go straight through the wall as there is a stud right behind where the outlet will be. Do I have to get a ventilation technician or a roofer instead of a plumber? As far as I can see, all that's needed is about a meter of straight ventilation conduit and a piece of flexible ventilation hose!? 
A previous place we rented had a small rangehood that expelled the air straight into my hair (I'm fairly tall). So after some greasy cooking my hair was as greasy as the frying pan. "The 1950's look" was then easy to achieve.  :Cool: 
Anyway, I just don't get the point of having a rangehood that doesn't get rid of the air outside.

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## Bloss

> We have bought a Robinhood 90cm rangehood for our new kitchen and we want it to expel the air outside. This is a link to the hood . http://www.robinhood.com.au/products...00_Wall_Canopy
> The plumber promptly said that he had never connected a rangehood to evacuate air to the outside of a house before and could I help with advice on this!!! 
> Does anyone know how this should be done? Should we connect it to a "Witches hat" or to a hole in the eave (both suggested in the rangehood installation instructions). Can't go straight through the wall as there is a stud right behind where the outlet will be.
> .

  Your plumber seems not to have had much to do with range hoods. Seeems he is really saying he doesn't want to externally vent it!  :Frown:  The instructions are quite clear - he can do top or eve vent outlet - http://www.robinhood.com.au/product_..._operating.pdf 
They can be used in re-circulation mode where the air is drawn from above the stove through the filters and straight back into the room. These are properly described as range hoods that do not work - they will remove neither smells nor visible smoke. IMO you should insist it be externally vented. 
So you need to vent to the outside. This can be done through the roof - usually as straight a path up as can be had - using usually gal steel duct pipe with a DekTite to stop leaks through the roof and hat with insect screening on the top to stop water and insect ingress. This one comes with a 150mm adapter so 150mm piping is the go. :2thumbsup:  
I try to stay away from eve vents or flexible ducting unless there is no way to get good access with fixed ducting (and there are bends and adaptors of all sorts in the fixed pipe). The reason is that they impede airflow and also collect dust and oils drawn in through the range hood and therefore need cleaning quite often (or do not get clean and become a smelly unhealthy fire hazard!)

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## N0mad

Thanks Bloss, that is as clear as can be. I will avoid the eave vent and go for a pipe with a hat as you described. I thought that might be the best alternative but it is very nice to have it confirmed. There is a direct path to the roof from where the range hood will be and it's a tin roof so it should be a relatively easy install. With any luck there won't be any need for bends between the ceiling and the roof.   :Iagree:  
Roger  :Seflag:

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## Bloss

> Thanks Bloss, that is as clear as can be. I will avoid the eave vent and go for a pipe with a hat as you described. I thought that might be the best alternative but it is very nice to have it confirmed. There is a direct path to the roof from where the range hood will be and it's a tin roof so it should be a relatively easy install. With any luck there won't be any need for bends between the ceiling and the roof.   
> Roger

  Sometimes a rafter or truss just needs a little bend in the pipe to get around,  but they are commonly available from pluming supply shops.

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## N0mad

Talked to the plumber again, it seems that his problem is that he doesn't know if (or where) he can find the witches hat part. Go figure!?

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## Vernonv

Should be able to get them at any plumbing place.  :Confused:  
Sounds to me like he doesn't want to do the job.

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## Bloss

> Should be able to get them at any plumbing place.  
> Sounds to me like he doesn't want to do the job.

   :What he said:  If he is plumber worth his salt he could make a witch's hat in 30mins or so!

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