Talk:Stack effect

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SI equation was wrong[edit]

The constant of 0.342 was incorrect. I changed it to 0.0342 for pressures in kPa which I subsequently changed to 34.21 for pressures in Pa. The P was defined incorrectly as total pressure. I changed the definition to ΔP being the available pressure drop. I also added a caution that the equations only applied to buildings and they do not apply to combustion chimneys.

It very depressing to find mistakes like this in article. I can only assume that someone found the equation in the USA customary units and then made an order-of-magnitude error in converting to SI units by misplacing the decimal point. Such errors would not happen if people learned to always make a sanity check calculation before publishing an equation.- mbeychok 07:10, 12 April 2006 (UTC)

  • It IS very depressing to find grammatical errors like this in AN article. Such errors would not happen if people learned to always proofread before publishing a statement. -- P199 12:33, 13 April 2006 (UTC)
Very cute!! But it evades the point that there are all too many mistakes in many of the Wikipedia technical articles. - mbeychok 15:43, 13 April 2006 (UTC)
The split infinitive "to always proofread" has gone unremarked for over a decade. This is very depressing. (talk) 04:20, 8 January 2017 (UTC)

Reverted the move and name change by User:Tmangray[edit]

User:Tmangray moved and changed the name of this article to "Chimney effect" simply because he unilaterally decided that it was a more common name than "Stack effect". I disagree with his change and with his having done so without any prior notice or discussion here on this Talk page. The most common usage by far in thousands of industrial plants and power plants worldwide is "Stack effect" as well as in the engineering/technical literature.

There is an existing article called "Chimney" in Wikipedia which has a section, Chimney#Chimney_draught_or_draft, devoted to the subject of stack effect or chimney effect. Any non-technical reader would probably go there first and would find that section. They don't need this article as well.

This article was intended for a more technical readership that encompasses industrial people (engineers, plant operators, plant managers) as well as science and engineering students,

I don't mean to be disrespectful or snide, but I don't think that User:Tmangray should appoint himself to unilaterally be the arbiter of what term is more common. Using the advanced search function in Google, the phrase "stack effect" got 71,000 hits and the phrase "chimney stack" got 49,400 hits. I have reverted the move and name change back to what it was before User:Tmangray changed it. - mbeychok 21:36, 18 July 2006 (UTC)

Just a postscript thought for User:Tmangray to consider: why not redirect Chimney effect to Chimney? Would that serve your purposes? - mbeychok 21:43, 18 July 2006 (UTC)

  • I started this article (while Mbeychok greatly expanded it) and my intent was to explain the technical/physical aspects of the stack effect - this is the proper term because (as is explained in the article) the effect is not just limited to chimneys. Therefore I completely agree with User:Mbeychok on all his points and this article should remain "Stack Effect". -- P199 17:25, 19 July 2006 (UTC)

Nonsense qualification[edit]

The article currently says: "The equation applies only to buildings where air is both inside and outside the buildings." Does that really need to be said? How many buildings are there that do not have air both inside and outside? The few I can think of are vehicles like submarines and spacecraft, or structures like storage tanks, none of which are buildings as such. 19:10, 30 April 2007 (UTC)

Actually, it might be worth stating. An example of a "building" where this isn't the case is on board a ship. The boiler would be below the water line, requiring air to flow down prior to flowing up. Another example: shipboard fires. If there is a fire that is in a vertical compartment (ie, ladderwell) where the top is at teh waterline, the air would flow down, then back up, possibly effecting the dynamics. I'm not enough of an expert in either to quantify the effects. —Preceding unsigned comment added by (talk) 16:00, 20 June 2009 (UTC)

Link missing[edit]

Ref 3 link is dead

Regards, Tom (talk) 07:38, 23 February 2009 (UTC)
:₳New link is Kennethjyoung (talk) 00:20, 4 July 2009 (UTC)

Reference cited doesn't provide equation used in article[edit]

That pressure difference ( ΔP ) is the driving force for the stack effect and it can be calculated with the equations presented below.[1][2]

The equation used in the article doesn't match the citation reference equation. Kennethjyoung (talk) 00:28, 4 July 2009 (UTC)

Removed External Link[edit]

The external link directed me to a page that was essentially a purchase page for a related book. Very little useful information about the Stack Effect on the page itself. Removed the link. —Preceding unsigned comment added by (talk) 14:42, 5 March 2010 (UTC)

But if the book's content is highly relevant, the link is appropriate; relevance of the web page about it is not the appropriate metric. (I haven't looked at the edit, link or book in question yet, but rationale given suggests the removal was inappropriate.)--Elvey(tc) 21:22, 14 June 2016 (UTC)

missing explanation, where the constant C stems from[edit]

there should be a remark, how C was derived, which assumptions it is based on to make this number traceable. —Preceding unsigned comment added by (talk) 08:57, 10 November 2009 (UTC)

The C seems to be, at least partially, a unit conversion factor. It is also simplifying away a lot of the physics details, hiding other factors like the densities of air and the flue gases. This article is missing a lot of the physics discussion one would expect in an article about fluid mechanics. A more thorough exploration of the topic is given here, on The Engineeering Toolbox. Unfortunately they don't appear to cite sources either. It's been mentioned already that our article here cites a source that doesn't even contain this equation. Saprophage (talk) 18:16, 10 January 2016 (UTC)


Surely C is not the same in U.S. customary units as in SI units!?!--Elvey(tc) 19:45, 14 June 2016 (UTC)


Huh? Basic physics errors?[edit]

Am I missing something or is something very wrong? We speak of hot air sucking smoke up a chimney/hot air up a stack, but physically, that's inaccurate. It's the pressure of the atmosphere pushing down that causes the less dense hot air to be pushed up the chimney/stack. So the image and caption (replicated at right:

The stack effect in chimneys: the gauges represent absolute air pressure and the airflow is indicated with light grey arrows. The gauge dials move clockwise with increasing pressure.

) is all wrong, no!? Air density is low in/near the bottom of the chimney, but the air pressure isn't. Right? According to the source,, (page 9, slide 2) indoor and outdoor air at the same altitude is not at the same pressure but I'm pretty damn sure the source is inaccurate. Anyone have a more authoritative source handy to confirm I'm right? --Elvey(tc) 21:22, 14 June 2016 (UTC)

By the way, if it were accurate, the inflatable chimney idea would face a likely insurmountable challenge: if there were relatively low air pressure, as depicted, in/near the bottom of the chimney, it would tend to cause it to collapse/be crushed by the outside air pressure. --Elvey(tc) 21:22, 14 June 2016 (UTC)