chimney pulling

[Ciaci]

Hi all,

I would like to calculate the pulling of a chimney (already installed). This chimney is connected to a pellet stove with a nominal thermal power of 17 kW.

The chimney is in stainless steel 316 L, Diameter DN 130. Its height is 9 meter and in the path there are nine 45° elbow.

Could you recommend me some formula or excell.. to calculate that value of pulling? I would like to verify that the chimney pulling will not be less than the required one by the pellet stove, that is 11 mbar.

Thank you so much

 

[georgeverghese]

Presume what you mean here is the draft pressure created at the bottom of this chimney by the hot flue gas from this pellet stove ?

 

[ione]

The natural chimney or stack draft is computed as follows:

ΔP = C*P*h*(1/To – 1/Ti)

where:
ΔP = pressure difference, in Pa
C = 0.0342
P = atmospheric pressure, in Pa
h = height of the chimney, in m
To = absolute outside air temperature, in K
Ti = absolute average temperature of the flue gas, in K


The diameter of the chimney and the fittings doesn’t play any role in natural draft calculation. They will be anyway indispensable to evaluate the flue gas pressure drop along the chimney.

 

[ione]

Francesco,

I suppose you’re from Italy, so I’ve taken the liberty of attaching a document that could be useful for your purpose.

 

[willard3]

What you want to calculate is chimney draft or stack draft

http://www.rumford.com/draft.html