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Round Flue Vs . Square Flue

Posted: Sat. Apr. 22, 2017 10:43 am
by Den034071
See New Chimney Post jack

Re: Round Flue Vs . Square Flue

Posted: Sat. Apr. 22, 2017 11:01 am
by Hambden Bob
Seems that's always been a Deep Discussion here,and rightfully so...

The Round vs Square/Rectangular Theories have been a part of Stove Design Discussion for better Combustion Characteristics and Thermodynamics.....

I'm towards the Round Crowd myself. The Cylindrical Swirl seems to make it go well,in less than Laymans' Terms !

Re: Round Flue Vs . Square Flue

Posted: Sat. Apr. 22, 2017 11:31 am
by coaledsweat
Not sure if I'm correct here but I'll give it a shot. The area to surface ratio is better on a round flue. Along the surface of the flue, the movement of gasses is stalled and turbulant, at center, the flow is laminar. The less surface area, the lower the amount of velocity upset per square inch of cross section. Make sense?

Re: Round Flue Vs . Square Flue

Posted: Sat. Apr. 22, 2017 12:24 pm
by Rob R.
I think insulation and height makes more difference than square or round, assuming the flue is properly sized.

Insulated round flue would be my top choice.

Re: Round Flue Vs . Square Flue

Posted: Sun. Apr. 23, 2017 6:54 am
by Sunny Boy
Rob R. wrote:I think insulation and height makes more difference than square or round, assuming the flue is properly sized.

Insulated round flue would be my top choice.
That would be my assumption too.

It's heat differential and retention of that heat, plus height, that is the driving force to make draft.

I had a 3 story high, 6 inch round single-wall pipe chimney for my potbelly stove. Very difficult to not have back drafts when starting a cold stove. And once the stove was running, the draft was too poor to idle the stove down because of the heat loss in the chimney.

I have a tall brick chimney now, no liner with rounded corners. My range has about the same coal capacity as my small potbelly stove was. With this brick chimney - built back in the days at the height of coal use - it is easy to start a fire, and the range will idle for hours at a steady burn as low as .005 mano reading.

Paul

Re: Round Flue Vs . Square Flue

Posted: Sun. Apr. 23, 2017 7:40 am
by oliver power
I agree with others. Really doesn't make a difference. I do like the round flue better. Don't really know why. MAYBE a little stronger than the square flue. One thing for sure, the round would give more room for insulation. I put round in my masonry chimney.

Re: Round Flue Vs . Square Flue

Posted: Sun. Apr. 23, 2017 7:52 am
by waldo lemieux
I had a round flue before I switched to coal. It was always easier to clean a round flue with creosote buildup, no corners...

Re: Round Flue Vs . Square Flue

Posted: Sun. Apr. 23, 2017 7:55 am
by freetown fred
That's why they make square brushes WL. LOL

Re: Round Flue Vs . Square Flue

Posted: Sun. Apr. 23, 2017 8:05 am
by waldo lemieux
They make brushes that are square???? :oops: I always bought a oversize round brush and took it down to my barber to make it square, used to charge me extra to get his scissors sharpened after....

Re: Round Flue Vs . Square Flue

Posted: Sun. Apr. 23, 2017 8:14 am
by freetown fred
That's a good barber my young friend :)