[Stoves] smoke hoods for cookstoves

[Kevin Chisholm]

Dear Paul

The reasons why exhaust hoods fail are as follows:

1: Insufficient air supply.
* Cure: Open door and window on upwind side of house

2: Insufficient stack temperature for the size of the stack
* Cure: Enlarge stack diameter, increase height of stack,  or reduce air 
ingress to hood

3: Exhaust Hood too lip high
 * Cure: Lower hood

4: Side Drafts blowing smoke sideways:
* Cure: Side skirts

There is not enough information to design, from afar, a hood that would 
work. Following is an empirical approach to exhaust hood design....

You can make a TEMPORARY test hood and sideskirts  using wood panelling 
or even corrugated cardboard.  Locate the stove as close to the back 
wall as is practical and safe. Make an exhaust hood horizontal 
dimensions equal to the width of the stove, and the distance from the 
front of the stove to the wall. Mount it as close as possible to the top 
of the stove, while allowing convenient viewing of pot contents and 
adding/removal of covers.  Hang side skirts down to stove level. Install 
a "stop plate" at the  level of the top of the stove, covering the space 
between the side skirts, the wall, and the stove top. Try a 6" (150mm) 
diameter exhaust pipe,  about 1 meters long, venting inside the living 
space. If this doesn't collect most of the fume, then find ways to 
minimize the front opening area. Once you get a hood that works, then 
you can permanently install the exhaust pipe to teh outside. Do a 
cooking test, and go by what the Cook says about whether or not the hood 
is in the way of convenient movement and vision. Then make a permanent 
hood and side skirt installation from sheet metal.

If you could send along a picture of the stove in place, perhaps I could 
make more specific practical suggestions.

Best wishes,

Kevin

Paul S. Anderson wrote:
> Dear All,
>
> My thanks to the many who responded.  Dean, Lanny, and someone with the 
> link to
> the older BoilingPoint article really shed some light.  I am not going to move
> toward hoods.  The very low-income people have other priorities more important
> than the limited usefulness of hoods.
>
> I and my two assistants are operating my residential-size TLUD inside 
> with only
> window and door ventilation mentioned in my previous message.  Results are
> good.
>
> And I have the easy option to add a chinmey.
>
> So hoods are out for me unless other info is forthcoming.
>
> Thanks again,
>
> Paul
>