Stack Effect Calculator

carlherrnstein · By: **carlherrnstein** On: Thu Aug 09, 2012 1:39 pm

I found this and thought it could make life simpler http://www.wisdomandassociates.com/educ ... ulator.htm I am guessing the height is in feet and the inside and outside temps are in degrees F. I think the inside temp should be the temp of the flue gas leaving the appliance. It spits the stack effect out in pascals which can be converted to inches of water here http://www.convertunits.com/from/pascal ... ter+column

lsayre · By: **lsayre** On: Thu Aug 09, 2012 6:25 pm

Very cool! I wonder why they chose to mix Fahrenheit and Pascals? That part seems a bit odd.

steamup · By: **steamup** On: Fri Aug 10, 2012 5:13 pm

Be very, very careful. If it is using pascals, it is probably using celcius for temperature.

This web page has both english and metric charts....

http://www.engineeringtoolbox.com/chimn ... d_175.html

rberq · By: **rberq** On: Fri Aug 10, 2012 8:01 pm

carlherrnstein wrote:I found this and thought it could make life simpler

Sure didn't make mine simpler. Is this saying the temperature of the flue gas doesn't matter -- it is only the difference between room and outdoor temperatures that counts?

Can somebody summarize this in English? Then I will use Steamup's link to translate to Traditional Chinese and I will know as much as I do now.

EarthWindandFire · By: **EarthWindandFire** On: Fri Aug 10, 2012 8:26 pm

I found this link today when researching chimneys.

http://www.woodheat.org/how-chimneys-work.html

lsayre · By: **lsayre** On: Fri Aug 10, 2012 10:26 pm

EarthWindandFire wrote:I found this link today when researching chimneys.

http://www.woodheat.org/how-chimneys-work.html

That site was quite helpful. One pascal is 0.004" of water column.

Lightning · By: **Lightning** On: Sat Aug 11, 2012 9:30 pm

lsayre wrote:
EarthWindandFire wrote:I found this link today when researching chimneys.

http://www.woodheat.org/how-chimneys-work.html

That site was quite helpful. One pascal is 0.004" of water column.

So, if I did this right.. I have about a 25 foot chimney and I'm gonna say my flue gases were about 100 degrees hotter than the outdoor temps since my pipe ran about 140 degrees give or take a few.. According to the chart that should yeild 16 pascals or a .064 inches of water on the manometer right? Question is, what about the temperature of the gases as they rise thru the stack and cool down? Oh, thats why my manometer usually read a .02 to a .04 I'm guessin.. Hey Fred the rocket science is back again :lol:

lsayre · By: **lsayre** On: Sat Aug 11, 2012 9:34 pm

Lightning wrote:So, if I did this right.. I have about a 25 foot chimney and I'm gonna say my flue gases were about 100 degrees hotter than the outdoor temps since my pipe ran about 140 degrees give or take a few.. According to the chart that should yeild 16 pascals or a .064 inches of water on the manometer right? Question is, what about the temperature of the gases as they rise thru the stack and cool down? Oh, thats why my manometer usually read a .02 to a .04 I'm guessin.. Hey Fred the rocket science is back again

The trick is to apply to the formula the average internal chimney temperature, which would presumably be substantially below the temperature of the flue pipe.

steamup · By: **steamup** On: Mon Aug 13, 2012 8:49 am

The inside temperature is the temperature of the flue gases, but after the barometric damper or draft device. This temperature will be lower than the unit's stack temperature.

Remember, your manometer is reading BEFORE the draft device. The purpose of the draft divertor or manual pipe damper is to compensate for too much draft.

The chart also assumes readily available combustion and dilution air. If there is a restriction of this air, the draft will read lower.

Stack Effect Calculator

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