AA 260 Chimney Size

 
lprince
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Post by lprince » Wed. Oct. 10, 2018 5:29 am

OK so about 4 years ago I scored an AA260 and started building a room on the side of my house to install it in, well as life goes and some serious medical issues for my wife the project went on hold. Everything is better now and I am on big push to get this beast back to work.

When I started this project I never really gave any thought to the chimney. I was considering using triple wall duravent stainless, but I am now having second thoughts. I guess I thought since the unit has a fan it induces its own draft this product would be fine but I believe my thought process is flawed.

So the question is based on experience If I would go with an all masonry chimney what is the minimum flue size I should use? The boiler is heating a 30x40 bilevel house in North East Pa Pocono Mountains. I currently have a 100K BTU oil boiler heating the house with 5 separate zones. I will be adding an additional zone directly off the AA260 to a 50K btu forced hot air water coil to keep the basement warm. So the Beast will never a significant load and never run near capacity.


 
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hotblast1357
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Post by hotblast1357 » Wed. Oct. 10, 2018 5:53 am

I have a 8x8 tile lined block chimney I put up for my 260, but I don’t see why 6” Duravent wouldn’t work.

Of coarse block and tile lined is the done once solution.

 
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coaledsweat
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Post by coaledsweat » Wed. Oct. 10, 2018 6:26 am

Six inch is not big enough for the chimney in my opinion. While a 260 doesn't require a good draft at idle, it has to move a lot of air when humping and that air is going to want to expand. Six inch isn't what you want.

 
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Post by lprince » Wed. Oct. 10, 2018 7:42 am

Caoledsweat what size do you think would be sufficient?

 
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Rob R.
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Post by Rob R. » Wed. Oct. 10, 2018 7:45 am

You can always call Pete Axeman for his recommendation.

The AA260 spec. sheet says 12"x12"x15' for the AA260.

 
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hotblast1357
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Post by hotblast1357 » Wed. Oct. 10, 2018 7:45 am

coaledsweat wrote:
Wed. Oct. 10, 2018 6:26 am
Six inch is not big enough for the chimney in my opinion. While a 260 doesn't require a good draft at idle, it has to move a lot of air when humping and that air is going to want to expand. Six inch isn't what you want.
Well then you better rebuild the design of the 260, cuz it’s a 6” outlet.

 
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Post by Rob R. » Wed. Oct. 10, 2018 7:49 am

No one is disputing the 6" breech on the 260. The intent is to keep the velocity high in the pipe between the boiler and the thimble, and allow the gasses to expend once inside the chimney. This is what prevents the fan from pressurizing the chimney,


 
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hotblast1357
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Post by hotblast1357 » Wed. Oct. 10, 2018 7:51 am

So your saying from the breach to exit, if it’s only 6”, same size as the exit collar, the draft will go positive?

 
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coaledsweat
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Post by coaledsweat » Wed. Oct. 10, 2018 8:01 am

hotblast1357 wrote:
Wed. Oct. 10, 2018 7:45 am
Well then you better rebuild the design of the 260, cuz it’s a 6” outlet.
Most solid fuel appliances have a 6 inch breech, name one manufacturer that recommends a chimney the size of the appliance's breech. At minimum, a chimney flue should be 25% larger than the thimble. The stovepipe itself will see the gas pass in a laminar flow. Once it reaches the chimney, that flow becomes turbulent and the gas wants to expand. Both of these changes require more room. That requirement gets a bit more important with an Axeman due to the size of it's combustion blower. It is huge and moves an enormous amount of air.

No need to redesign the Axeman, it's perfect. The proof of that is the design has remained unchanged for 7 decades.

 
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Rob R.
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Post by Rob R. » Wed. Oct. 10, 2018 8:09 am

hotblast1357 wrote:
Wed. Oct. 10, 2018 7:51 am
So your saying from the breach to exit, if it’s only 6”, same size as the exit collar, the draft will go positive?
No. I am saying if the pipe from breech to thimble AND the chimney flue are 6", it won't work as intended.

I'll repeat my recommendation to just call Axeman Anderson. They have been making these things for almost 70 years and have a good idea what is needed.

 
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hotblast1357
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Post by hotblast1357 » Wed. Oct. 10, 2018 8:18 am

Page 4. Not less than 6”.

http://hitzer.com/uploads/page/Files/50-93__30-95 ... d_2016.pdf

Page 2. 8” breach, requires 8”x8” square tile.
http://cdn.efmheating.com/DF520.pdf


I’m looking for some more..

 
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Rob R.
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Post by Rob R. » Wed. Oct. 10, 2018 8:22 am

hotblast1357 wrote:
Wed. Oct. 10, 2018 8:18 am
Page 4. Not less than 6”.

http://hitzer.com/uploads/page/Files/50-93__30-95 ... d_2016.pdf

Page 2. 8” breach, requires 8”x8” square tile.
http://cdn.efmheating.com/DF520.pdf


I’m looking for some more..
You can stop looking, and please stop confusing the original poster by referencing equipment with a totally different design. Natural draft appliances or stokers with a combustion fan on the cold side of the fire are different animals.

If you want to post links to manuals, post the one for the AA260.

 
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coaledsweat
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Post by coaledsweat » Wed. Oct. 10, 2018 8:35 am

lprince wrote:
Wed. Oct. 10, 2018 7:42 am
Caoledsweat what size do you think would be sufficient?
My Axeman has about a 16' chimney and 10" square tile. I've had problems with my old hand fired but none with the Axeman as far as the chimney goes. I would not go smaller than 10" though, especially at that height.

 
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hotblast1357
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Post by hotblast1357 » Wed. Oct. 10, 2018 8:35 am

It took me a while to find it rob, those other references where for coaledsweat to read about.

Page 11, minimum flue size is 6” for the 260.

https://greenftechn.com/downloads/CommercialCoalG ... l05.25.pdf

 
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Post by Rob R. » Wed. Oct. 10, 2018 8:38 am

http://www.axeman-anderson.com/pdf/anthratube.pdf

Last page has the chimney recommendations.


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