Secondary Air Distribution System

 
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Lightning
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Post by Lightning » Sun. Jan. 18, 2015 3:51 pm

No, that's fine.. :)

Feel free to start a thread with your intentions. You'll get plenty of great information.


 
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Post by hotblast1357 » Sun. Jan. 18, 2015 5:04 pm

I would try the actuator first because there is no chance of making the system positive pressure, it will all be done through the draft of the chimney, which I feel much safer with then a combustion fan, my thread lightning posted I believe has all the answers, if not, feel free to PM me anytime.

 
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Post by Indiana dave » Sun. Jan. 18, 2015 5:18 pm

Thank you , I'll read into your thread some more!

 
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Post by davidmcbeth3 » Sun. Feb. 07, 2016 12:39 am

I've seen caps like this:
Image

Find ones that fit its just a matter of pulling in and out to regulate. Jeeze ... brain FART OP is 3 yrs ago...I'm sure he fugured out something by now..

 
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Post by Lightning » Wed. Oct. 26, 2016 8:43 pm

Lol, I just saw that post David, guess I'm a little slow to the party too :lol: I ended up using caps just like those.

I captured a couple cool pics thru the window tonight of the secondary air doing its thing after igniting a fresh batch.

Check out the right side :)

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Post by scalabro » Wed. Oct. 26, 2016 9:09 pm

Those are gorgeous pictures Lee!

 
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Post by Lightning » Wed. Oct. 26, 2016 9:15 pm

scalabro wrote:Those are gorgeous pictures Lee!
Thank you Scott :)


 
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Post by KingCoal » Fri. Oct. 28, 2016 1:19 pm

Lightning wrote:
hotblast1357 wrote:Lee, what kind of equation did you use to figure out the 25 1/4 in holes are equal to a 1/1/4 pipe, I'm using a 3/4 in pipe and want 1/8 in hole, 18 inch long pipe
Area = Pie (3.14) times (radius squared)

So for the 3/4 inch pipe Area = .44 sq in
1/8 inch holes are .012 sq in
1/4 inch holes are .049 sq in

So according to this, it would take roughly 36 holes at 1/8th inch to equal the area of the 3/4 inch pipe (inlet).. You would need to space them 1/2 inch apart for the 18 inch length of pipe. This doesn't allow for turbulence around the small holes slowing air flow. I'm not sure if it would be enough. But its worth a try..

I would use bigger holes. 1/8th inch holes are pretty small.
It would take 10 holes at 1/4 inch per hole to roughly equal the area of the 3/4 inch pipe. You can add a couple more since turbulence around the holes will slow down air flow a little. You could use 12 holes (1/4 inch) spaced 1.5 inches apart for the length of the pipe..

Be keeping the collective small hole area in check with the size of the pipe, it will help with getting an even distribution down the length of the pipe..
Hey Anthra-Man,

going off this post, and working out the exit holes for the 48" long ring of 3/4" conduit making up the new secondary in T.O.M. it seems I should use 1/4" holes roughly 4.5" apart.

that would also roughly mirror the pattern in the GW #6 since my secondary tract is fed from both ends like the GW #6.

what do you think, should I throw in a couple more since the GW #6 actually has 12 and because i'll undoubtedly have some turbulence ?

thanks,
steve

 
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Post by Sunny Boy » Fri. Oct. 28, 2016 1:58 pm

If you have too many holes, air being lazy will take the path of least resistance. Due to pipe internal flow resistance, more air is likely to come out the holes closest to the in-feed and less at the rear, furthest from the pipe's in-feed ends.

Better to be a few holes total opening area shy of the pipe's cross section and get more even distribution than to have the bulk of the air coming out closest to the in-feed.

Unless,....... the in-feed is 180 degrees across from the exit collar. Then it may prove better as it will tend to draw a higher concentration of secondary air over the middle of the firebed and give more complete combustion ????

Paul

 
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Post by KingCoal » Fri. Oct. 28, 2016 2:35 pm

Sunny Boy wrote:If you have too many holes, air being lazy will take the path of least resistance. Due to pipe internal flow resistance, more air is likely to come out the holes closest to the in-feed and less at the rear, furthest from the pipe's in-feed ends.

Better to be a few holes total opening area shy of the pipe's cross section and get more even distribution than to have the bulk of the air coming out closest to the in-feed.

Unless,....... the in-feed is 180 degrees across from the exit collar. Then it may prove better as it will tend to draw a higher concentration of secondary air over the middle of the firebed and give more complete combustion ????

Paul
i think GW may have had this calculated and dealt with in their design and , why I've been trying to copy it.

dual intake entries in front and a ring of exits, with the gas path leaving the barrel in the center of the back not far above the fire bed. this seems like it would over come the "lazy air" at the back of the ring, not ?

thanks,
steve

 
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Post by warminmn » Fri. Oct. 28, 2016 3:45 pm

Im redoing my frankenstoves secondary as I type. I plan on the pipe coming in on each side, wrap around half the stove each direction, and then have the opening holes on the oposite sides. I plan on burning a fair amount of wood the next 2 years and thought that should really heat the secondary air up before leaving better than now. I'll throw some before and after pics on here when done.

It was like a blast furnace before when it was open, but as you mentioned the 1st holes had more air coming out them and it did not always ignite because it wasnt hot enough air yet. its amazing the flames it created before so I cant wait to see what this does.

Several of you in this post and a couple other posts can be credited with helping my creation. Thank you

 
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Post by Lightning » Fri. Oct. 28, 2016 7:18 pm

KingCoal wrote:
Hey Anthra-Man,

going off this post, and working out the exit holes for the 48" long ring of 3/4" conduit making up the new secondary in T.O.M. it seems I should use 1/4" holes roughly 4.5" apart.

that would also roughly mirror the pattern in the GW #6 since my secondary tract is fed from both ends like the GW #6.

what do you think, should I throw in a couple more since the GW #6 actually has 12 and because i'll undoubtedly have some turbulence ?

thanks,
steve
Don't forget to factor in that your pipe has two entry points for secondary air where mine have only one. So basically you'd want to calculate for half the total pipe length.

Also, it's my own thought that location of the exit collar shouldn't influence the distribution itself since negative pressure inside the stove cavity should be the same everywhere inside it.

 
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Post by KingCoal » Sat. Oct. 29, 2016 6:00 am

Lightning wrote:
KingCoal wrote:
Hey Anthra-Man,

going off this post, and working out the exit holes for the 48" long ring of 3/4" conduit making up the new secondary in T.O.M. it seems I should use 1/4" holes roughly 4.5" apart.

that would also roughly mirror the pattern in the GW #6 since my secondary tract is fed from both ends like the GW #6.

what do you think, should I throw in a couple more since the GW #6 actually has 12 and because i'll undoubtedly have some turbulence ?

thanks,
steve
Don't forget to factor in that your pipe has two entry points for secondary air where mine have only one. So basically you'd want to calculate for half the total pipe length.

Also, it's my own thought that location of the exit collar shouldn't influence the distribution itself since negative pressure inside the stove cavity should be the same everywhere inside it.
rereading what I posted I see that I left out the part about thinking 10 holes would do it. :roll:

and if I should consider this loop as 2 / 24" pieces and the 3/4" area should be satisfied on each one it now seems like I should use twice that. is that your thinking ?

as to the internal negative pressure being equal in all places I remember you talking about that now. I know it will be correct for a closed container just not quite convinced it's an absolute in the case of our stoves. :oops:

with FRANK I could make very obvious changes in the profile and direction of the tips of the blues at the front door according to whether I was using the direct draft exit at the back wall or the indirect paths along the sides. the first time I noticed it it took me so by surprise that I changed it back and forth 6 times to verify.

thanks,
steve

 
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Post by Lightning » Sat. Oct. 29, 2016 1:22 pm

KingCoal wrote:and if I should consider this loop as 2 / 24" pieces and the 3/4" area should be satisfied on each one it now seems like I should use twice that. is that your thinking ?
Yes, unless you think that would be too much secondary air.

 
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Post by ddahlgren » Sat. Oct. 29, 2016 4:02 pm

As a bit of a thought experiment what would happen with the following changes. Bend up 2 more rings to go on top of the one with holes, the new rings have no holes at all other than air in from the room and the other to feed one side of the ring with holes.

The other idea is to have smaller holes next to air in now heated to some degree and larger ones toward the end of the 24 inch section in the rear.

Just thinking out loud playing what if but might address what you have seen in the past.


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