[Stoves] Cooking hood

[Kevin]

Dear Kobus

There could be a major difference between a "smoke hood" and a "cooking 
hood", in that the smoke hood would have the relative absence of grease from 
cooking. If the cooking was mostly boiling and simmering, the steam would 
not be a fire hazard. However, if the cooking was mainly frying, there could 
be a significant grease absorption on the hood surfaces, creating a possible 
fire hazard. The chimney should be generously sized, to encourage good 
ventilation, and thus cooling. There should be sufficient "air inlet area" 
to the kitchen, to allow for entry of "make-up air." Elbows to get through 
the wall should be sloped, so that if there was grease buildup, it would 
drain back and signal a need for cleaning, rather than pooling and building 
up where it could not be seen. A vertical chimney, through the roof, would 
be best from a draft standpoint, but is structurally more complex, because 
of roof leakage considerations. The penetration through the wall or roof 
should have a "thimble" that creates an air space, with no contact of the 
chimney with combustible material. In warm climates, where heating of the 
living space is not a problem in Winter, an open space can be left around 
the chimney, but if such air loss would be excessive, the space should be 
filled with fiberglass insulation.

The hood needs a velocity of about 100 feet per minute around its open 
perimeter for good pick-up of smoke and grease. (EG, a hood that was 2'x2', 
located in the center of the room, would have an open  perimeter of 8 feet, 
and the flow should be a total of about 800 CFM.  If the stove was located 
in a corner, the same sized hood would only have an open perimeter of 4', 
and would only need a flow of about 400 cfm. To keep the size small, it 
should be mounted as low as, and as close to the top of the cooking area 
that will be convenient for the cook.

Welding is not necessary. Sheet metal can be held together with "angled 
brackets", that are attached to the sheet metal at the joints by rivets. 
Rivets can be made from short length of thick copper wire.

Best wishes,

Kevin

----- Original Message ----- 
From: "Kobus" <ventfory at iafrica.com>
To: "stove list" <stoves at lists.bioenergylists.org>
Sent: Monday, May 30, 2011 3:54 AM
Subject: [Stoves] Cooking hood


>
> Content analysis details:   (0.0 points)
>
>  pts rule name              description
> ---- ---------------------- --------------------------------------------------
> _SUMMARY_
>
> Does anybody know whether or not it is possible to construct a 'cooking 
> hood' out of material other than metal? I've had a query from a Peace 
> Corps volunteer in Cambodia where they don't have access to welding 
> facilities. The hood is to be positioned above a rocket stove, akin to 
> what you'd expect to find in a 'stove test hood' to catch emissions. Not 
> looking for a 'for' and 'against' hood discussion here but to ask if 
> anybody has any knowledge on this or have any suggestions.
>
> Thanks
>
> -- 
> ________________________________
> Kobus Venter
> http://www.vuthisa.com/
> http://za.linkedin.com/in/vuthisa
>
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