Secondary Air Distribution System

Lightning wrote:

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.

i have to admit I don't know if it's too much or little but, this is what I propose to do. I will put in 17 - 1/4" holes one every 3" around the ring.

if there is equally strong release i'll consider it good unless, it seems to be washing out excess heat. in which case I will use some caps and begin experimenting with restricted entry. if the release is weak in back i'll enlarge some of those holes.

i will also begin work on a ring with 3 ascending revolutions ( to gain more pre-heating ) with holes only in the upper and last radius.

onward,
steve

3 questions.

If built in 1 piece with 3 loops how does it go through the door?
If 2 inlets with one at each end don't the holes need to be in the middle loop?
How much secondary air do you need?
Is there some way to compare what other stoves use?
My wood stove while not a coal stove had 1/8 holes around 1 inch apart and 16 inches long. Wood is primarily volatiles and that seemed to do the job at least for wood. My concern with 1/4 holes is if you find out that you have way too much air capacity and run them only 1/2 open the air will bleed out the first holes without ever making it to the rear.

Again another thought experiment and do with it what you like as it is all a big experiment in the first place.

ddahlgren wrote:3 questions.

If built in 1 piece with 3 loops how does it go through the door?
If 2 inlets with one at each end don't the holes need to be in the middle loop?
How much secondary air do you need?
Is there some way to compare what other stoves use?
My wood stove while not a coal stove had 1/8 holes around 1 inch apart and 16 inches long. Wood is primarily volatiles and that seemed to do the job at least for wood. My concern with 1/4 holes is if you find out that you have way too much air capacity and run them only 1/2 open the air will bleed out the first holes without ever making it to the rear.

Again another thought experiment and do with it what you like as it is all a big experiment in the first place.

thank you very much for bringing up these points, I had considered them last night and intended to comment on them today.

because i'm using a standard bending "shoe" on a piece of pipe, by the time you have 180* done the material naturally hits the support pipe and you need to decide which side you are going to let it coil to. I flattened mine out after I cut off the excess.

if i'm going to do a "tiered" coil I will only "compact" it enough for each revolution to lay close to the last. to get them in the stove they will need to have an 8" gap which I will close and seal with unions. I see only having one inlet on the spiral and the far upper end capped or crimped off. the hole would only be in the upper revolution.

the over all biggest concern, which you have seen too, is the relationship of secondary air to the rest of the stove, and like you I believe there are lessons to be learn by comparison of other systems and the relationships between fire bed surface, combustion chamber and air tract volume as well as number and size of holes.

i'll use FRANK for comparison. the top of the fire pot is 16 x13 or 208 S.I. the combustion chamber is 21x20x15 or 6300 C.I. the air tract is 21" of 1" square tube open at each end with 9 - 3/8" holes with the odd one in the center and the others flanking it one each side.

now T.O.M. has a fire pot 16" across and like FRANK verticle sides. that's 201 S.I. the combustion chamber however is only 4020 C.I.
and the air track is 3/4" round tube, 46" long, if measured along the centerline, fed at both ends and having an undetermined number and size of holes.

so FRANKS air tract volume is 1 x 21 or 21 C.I. and TOM's is .44 x 46 or 20.24 C.I. for basically the same size fire pots.

so how do we reconcile the combustion chamber volume diff. to this and the number and size of holes needed ?

gotta go for now, i'll be back.

thanks,
steve

I wonder if the amount of secondary air needed is related to the amount of coal burning. If anthracite in general has 3% to 5% volatiles would the amount of secondary be proportional to the amount of coal burning and a given percent of volatiles in the coal?

The next and for me more confusing question that may or may not happen is this. Once you light secondary's does the added heat invite more volatiles to burn more easily? I am making the assumption the burning volatiles do add heat otherwise nothing to gain.

More food for thought.
Dave

Dave,

i have put links to our last 3 exchanges over in my own "new era base burner" thread to keep this one on Lee's topic and the experimental discussion over there.

thanks,
steve

So Im almost done playing with my frankenstove again. What I did now is I used the same 2 inlets for secondary air, with 3/4" pipe thru each, only now I wrapped the pipe around the stove with the drilled holes on the opposite side of the entry point. My quest was to have the air heated better before it came thru the drilled holes, as it seemed to not always ignite on the first 2 or 3 holes after entry (too cold) before. The threaded rod is just to put a plate on top of for a baffle, and that baffle is 3-4" above the air holes and is what you see in one pic.

The other difference this time is I only have 8 holes instead of 10, as I know I will have some leaks from not being able to tighten the corner pipes as well as I wanted too or I'd lose the angle. I used the same outlet pipes (drilled ones) with new pipe before it. I have to get the top on yet, and wait a couple days for refractory to dry then it will be burning wood for about a month before anthracite. Im hoping the extra couple bends in the one pipes entry wont matter but time will tell. I didnt want to have a drill another hole in the stove.

The thing that the pipes sit on is what held the top of the 2nd row of bricks before.

I had two rows of firebrick in this beast and I took out the top one and covered over the bracket for them and up a couple inches with refractory so I will have more of the shell exposed to the heat too. (plus it used to turn the stove red where that bracket was ) I didnt do a great job with the refractory but good enough for me. In all likelyhood this will eventually be a wood only stove in another year or two in a shed, but for now is my main unit, with jr picking up the slack on cold days and off seasons.

I promise videos of the burn in the future but for now just a couple coal *censored* pics.

Cool man! I'm looking forward to seeing it in action.

Here is my take. 30" black iron. I used the idea here of a floor flange for control.

Thank you Lee for the idea.

bjefferys wrote: ↑

Sun. Sep. 15, 2019 10:48 am

Here is my take. 30" black iron. I used the idea here of a floor flange for control.

Thank you Lee for the idea.

You are welcome, very nicely done Bro!!

Every single firebrick was cracked. Needed to replace them all. I needed to do a full clean out in prep for the cold anyway. Already stuffed the plates with fiberglass. Glass is on the way for the door and the grates are upside down. Need to do the shaker mod still. It is a must with these. I burn Bit and wood.

Nothing wrong with a cracked brick...it's the ones that crumble that need replaced.

Each brick was in multiple pieces. I was doing a full clean out anyway.

Got cool enough to fire up the box. Started at 7 am with Bit coal. Got a 12 hour burn. Temp outside was at 45. Got 12 hours before shake down. Could have gone 16 probably. Loaded at 7 pm. Another 12 hours. About 1/2 a pan of ash.

I also replaced the blowers with a furnace blower. Have the fan wired to high. It's controlled by my ecobee on stage 1 with a 24v relay while my propane furnace is stage 2 for backup.

Nice, what blower did you replace the two smaller blowers with?