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minimum velocity in a chimney

minimum velocity in a chimney

minimum velocity in a chimney

(OP)
Hi guys,
Does anyone know if there is a minimum flue velocity required by any standards for a chimney connected to a pellet stove. Following my calculation the velocity of the gas in this chimney is 0,49 m/s, that in my opinion is too low.
Infact a low flow velocity will allow particles to settle out and promote condensation of any creosote that may form.

Since I do not know any code or standard that cites the minimumu velocity for the smoke in the chimney, I would like to be helped.

Thank you in advance

RE: minimum velocity in a chimney

House use? I can't imagine a pellet stove being used commercially.

But think about your criteria and your concern: Place your hand on the floor, and try to raise it all the way to the ceiling at 1/2 meter/sec! That is a "lot" of air flow. Are you not more concerned about the replacement of that much combustion air in the room with cold outside air, and the drafts inside the room as that air is moved from the walls towards the stove?

RE: minimum velocity in a chimney

(OP)
house use! So do you think that 0,49 m/s is a fast flue velocity?

RE: minimum velocity in a chimney

FWIW this says 2 m/s is the max for "small" furnaces. Implication ( or my infer-ation ) is that is chimney velocity, but the source is missing and the wording is vague.

http://www.engineeringtoolbox.com/chimney-sizing-d...

If I had access to the ASHRAE handbooks I'd be checking there, after quizzing the pellet stove manufacturers.

RE: minimum velocity in a chimney

Your stove manufacturer should have data on the correct flue size. Keeping the fire too low and slow will be a bigger factor in creosote formation than flue size.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

RE: minimum velocity in a chimney

What kind of calculation? Is it a buoyancy calculation based on temperature assumptions, or a fan-fed flow?

RE: minimum velocity in a chimney

There is a section 30.2.1 In the book, "Hand book of HVAC design" by Nils Grimm and Robert C Rosaler on; "factory built vents Chimneys and stacks" that addresses some but not all of this. It does not mention stack velocity, however it does mention that stacks for wood pellet stoves be classified as requiring a stack that can withstand 3 ten minute cycles of 2030f to simulate burning creosote. It also mentions some dis agreement between US and Canadian authorities on just how this should be implemented.
B.E.

You are judged not by what you know, but by what you can do.

RE: minimum velocity in a chimney

Amantino,

It's a bit remiss of you not to advise that this post contains lots more info on your issue.

www.eng-tips.com/viewthread.cfm?qid=403655

A lot of this should be vendor driven

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: minimum velocity in a chimney

An open air bonfire or free-drafting campfire will not greatly exceed 1/2 meter per second. Look at the small sparks, or suspended little particles going upwards.

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