sizing a simple stack for heat draft off a furnace

[prichmon]

I am working on installing a simple hood with stack to draft the heat from a 1,000,000 BTU/HR furnace with a vertical escape and horizontal run. The unit uses a blower running ~7" WC. Furnace opening is ~3"x 36". My current plan is to use a simple rectangular sloped up hood attached to stove pipe with multi layer construction to keep the heat and velocity as high as possible.

I looked in the 12th edition MERM and could not find anything on this subject. I did find design height; Stack effect head; and a simple draft equation. Based on research on chimneys has lead me to believe a 12" diameter pipe ~16' horizontal run with ~20' rise to get the draft I require. My gut tells me 12" will easily work but I feel I could lower my cost by using a more common size such as 8". However I can't find any data to support my gut.

The goal is to provide as much draft as possible with as little cost. I wish to avoid using forced air to increase draft so I'm limited to the chimney draft effect or some other means.

Can anyone point me in the right direction for a reasonable assessment of flow and sizing?

Rich

 

[prichmon]

bumpy... Can anyone lend a hand?

 

[LittleInch]

I think you may have put this in the wrong forum. Most people who respond on this one are experienced in pipe and pipeline design, not fired heater design. Try local exhaust ventilation or search for simialr questions and see which forum got the better response.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[prichmon]

THANK YOU.