[Stoves] Air exchange RDP Homes

[Venter Forestry]

Dear David W and list,

Thank you for your insights, a hood definitely has potential then in these
areas when using good improved wood or charcoal stoves, but not so much
coal.  Improved stoves will no doubt be the way to go by venting cleaner
emissions in "smoke free zones".  

But what about the replacement of oxygen used by non electric stoves, good
or poor?   

Someone gave me the following equation to determine the air exchange in a
room (and CO buildup), but as of yet I have not been able to put it to use
as an example was not provided, and I am not well versed in these types of
things!  I would be grateful if anyone could assist.

He states:

mg/m³) from (t) = 0 to ti hr: ,

C (t) = [(E+O)/V][1/(a+k)][1-e-(a+k)t]

where E is your stove emission rate (mg/hr), O is the outdoor CO
contribution to indoors (mg/hr), V is the volume of your room (m³), a is the
air exchange rate (hr-1), k is the CO decay rate (hr-1), and t is time (hr).

Please note, you probably can assume O is 0, and k is 0 as well.

You may use the following equation to determine your indoor CO concentration
from the time you stop burning:

C (t) = [(O/V(a+k)][1-e-(a+k)(t-T)]+[Cmaxe-(a+k)(t-T)]

Cmax is the maximum CO concentration achieved.

Each habitable room and I quote the housing spec ..."must have an opening
not less than 5% of the floor area of the room, or 0.2 m2, whichever is
greater, comprising either of an opening or door in an external wall, or an
openable glazed window in an external wall or in a suitable position in the
roof"... The regulations also states that the floor space of each home is to
be 50m2. If windows and doors are shut (a scenario apparently not mentioned
by the writers) a ventilation opening of 140 x 140 mm in each room will
conform to these regulations. Are these openings sufficient to allow for the
use of non-electrical stoves indoors? 

Regards

Kobus

>Dear Kobus,

>In my opinion, hoods placed directly over or stoves placed directly under
hoods, with incoming >ventilation is a better option than a chimney.

>With a hood over a fire, the operator can see the burn and adjust if smoke
occurs. With most chimney applications I've seen or heard about, the
operator pays less attention >to the burn and if smoke occurs it leaves the
home often to enter the windows of the >neighbors. My wife heard so many
tales of this woe when she was in Mexico training solar >cooking promoters. 

>In Bolivia, we recommend using sticks or bamboo as a basic structure in a
corner, forming a triangle >from wall to wall, decreasing in width as it
increases in height, using mud or stucco to >plaster inside and out of the
structure of the hood and have an opening in the highest part directly >in
the corner if it is possible without harming the corner's structural
integrity. Then an open >door or open windows or shuttered hole low in the
opposite wall provides sufficient ventilation. >The top hole can have a
shutter or plug for when it is not in use, in the case of cold >climate.

>If good improved stoves are used, they should not smoke and the ventilation
will evacuate the >majority of harmful gases and particles, without causing
excessive outdoor pollution or bothering >neighbors.

>can discuss more off list if you wish.

>warm regards

>David Whitfield