A better explanation...

[Chris-PA]

L.O.L.
I'm lovin' the drawing Steve, but ya' forgot the air wash/primary, so I added it in red.

It's super easy to tell where the air wash/primary is reversing direction by looking at the glass on my door.
The bottom two-thirds is now a white milky, translucent color... the glass is permanently etched because it wasn't getting the cooling effect of the air wash.
When I got that thing it had been used a few years, yet the glass was crystal clear... and it stayed clear right up until the cold weather and operational problems started.
The transition from clear glass to etched glass is exactly where the newspaper smoke reversed direction during my "smoke bomb" test... which was very enlightening, the upper third (or maybe a bit more) of the firebox filled with thick, rapidly swirling, grayish-yellow smoke, the lower two-thirds barely even turned hazy... and even that took a couple of minutes before it did.

If I stop mine down for a long burn the door glass will cloud up too, but I don't get the coaling.

I think the drawing is a good illustration, but it's still a small firebox and I don't believe you can have that much airflow through the top half of it and get the bottom so starved for oxygen it coals.

I think the missing ingredient is burying the bottom logs in ash from a fast burning fire up top due to uncontrolled secondary air.

BTW - I like having an on-topic group discussion and figuring out real problems.

 

[Steve NW WI]

I think the missing ingredient is burying the bottom logs in ash from a fast burning fire up top due to uncontrolled secondary air.

I don't see enough ash to strangle the coals under it being a possibility, unless you're burning something like slabwood from a mill that's mostly bark. From what I've seen of Spidey's wood piles, I don't think that's the case. I can burn down a full load of red oak in my 3 1/2 cf firebox and only have enough ashes left to fill a small coffee can - far from enough to smother a fire. Lack of oxygen is much more likely.

 

[Whitespider]

slowp,
Look at the drawings... the coals are not getting air (oxygen), or at least very little air.
Without air they cannot burn and heat, they just smolder and eventually die.
It's sort'a like one of those "air doors" (if you've ever walked through one?)... a rapidly moving wall of air keeps the cold air outside, and the warm air inside.
In my firebox, during extreme draft conditions, a wall of turbulent air sets up above the coal bed, causing the coals to just recirculate the already oxygen depleted air in the lower firebox back onto themselves... no oxygen, no heat, and they eventually smother completely. That turbulent and rapidly exchanging air in the top of the box steals any remaining heat from the stove, carrying it out the flue. Unless I keep adding wood to keep the secondary burning... I'm pretty much just heating the out-of-doors during extreme cold weather. Adding wood continues to build the coal bed, until there ain't hardly room for wood... so then I shovel out all that potential heat to make room (so I'm wasting wood on a grand scale). For some reason that still doesn't make 100% sense, I can't modify the intake or the exhaust to get proper balance during extreme cold (draft). If I get the draft/intake/exhaust pulled down enough to shut off the "air door" effect... basically, I've shut the stove off. The stove, or more correctly, the combination of the stove design and my draft situation will not allow a "happy medium"... it simply doesn't work.

 

[Chris-PA]

I don't see enough ash to strangle the coals under it being a possibility, unless you're burning something like slabwood from a mill that's mostly bark. From what I've seen of Spidey's wood piles, I don't think that's the case. I can burn down a full load of red oak in my 3 1/2 cf firebox and only have enough ashes left to fill a small coffee can - far from enough to smother a fire. Lack of oxygen is much more likely.

That's a valid point, but how do you get hot coals to go out when there is high velocity air circulating a couple of inches over top of it? Those hot coals will create a lot of rising air and local circulation all on their own, mixing fresh air back down.

What makes the bed of hot exposed coals go out? The air that rises from them must be replaced by other air in the box, and that air contains oxygen from an abundant supply of fresh air moving through.

Is there some combustion condition here that causes more ash? Are the people with excessive coaling problems finding a lot of ash too?

 

[Whitespider]

Read my "air door" theory above... wad'ya think?

I gotta' believe there most likely is a "sweet spot" where the stove will run correctly, but it's so darn narrow you can't keep it there for longer than a few short minutes.

 

[Whitespider]

Is there some combustion condition here that causes more ash? Are the people with excessive coaling problems finding a lot of ash too?

That's an interesting question... and I'll tell you why.
During warmer weather and reduced draft, like the last few days, the firebox work pretty darn good, and when I clean the ash out it's super fine, light weight and whitish in color.
But during cold weather and increased draft (even when I purposely fiddle with the coal bed every half hour to get it to burn down) the ash is course, heavy and dark grey-to-almost-black in color (and full of un-burnt, small charred pieces of coal).
Not really sure what that tells us though... other than lack of enough oxygen.

 

[brenndatomu]

slowp,
look at the drawings... The coals are not getting air (oxygen), or at least very little air.
Without air they cannot burn and heat, they just smolder and eventually die.
It's sort'a like one of those "air doors" (if you've ever walked through one?)... A rapidly moving wall of air keeps the cold air outside, and the warm air inside.
In my firebox, during extreme draft conditions, a wall of turbulent air sets up above the coal bed, causing the coals to just recirculate the already oxygen depleted air in the lower firebox back onto themselves... No oxygen, no heat, and they eventually smother completely. That turbulent and rapidly exchanging air in the top of the box steals any remaining heat from the stove, carrying it out the flue. Unless i keep adding wood to keep the secondary burning... I'm pretty much just heating the out-of-doors during extreme cold weather. Adding wood continues to build the coal bed, until there ain't hardly room for wood... So then i shovel out all that potential heat to make room (so i'm wasting wood on a grand scale). For some reason that still doesn't make 100% sense, i can't modify the intake or the exhaust to get proper balance during extreme cold (draft). If i get the draft/intake/exhaust pulled down enough to shut off the "air door" effect... Basically, i've shut the stove off. The stove, or more correctly, the combination of the stove design and my draft situation will not allow a "happy medium"... It simply doesn't work.

BDR

that's a valid point, but how do you get hot coals to go out when there is high velocity air circulating a couple of inches over top of it? Those hot coals will create a lot of rising air and local circulation all on their own, mixing fresh air back down.


what makes the bed of hot exposed coals go out? The air that rises from them must be replaced by other air in the box, and that air contains oxygen from an abundant supply of fresh air moving through.

Is there some combustion condition here that causes more ash? Are the people with excessive coaling problems finding a lot of ash too?

Slow it down with BDR



By the way spidey, I just looked up the Daka furnace manual, page 7, and I quote

"Connecting Daka furnace to chimney

1. A barometric regulator should be installed in smoke pipe at least 18" from furnace, to permit adjustment of chimney draft to a maximum of .06" water column draft..."

...so now what?

 

[Whitespider]

My Jotul 600 has the air wash input but also has a main air input in the center front of the box right inside of the door at grate level. This air shoots directly into the firebox at grate level...

Ain't no grate in mine...
But there is air that comes in just below the door... it's a tiny unregulated amount called "Boost Air" by PE, supposedly to aid in starting a fire. (Look back through this thread, it's already been discussed). It will keep the coals closest to the door live, but they need to be within a couple inches of the air inlets... once those burn down it's all over but the crying.

Thinking about that... if my theoretical air door is present, the air coming in the "boost" has very little draft to pull more in.

 

[Chris-PA]

I'm surprised Spider's stove has no main air input other than the air wash system. My Jotul 600 has the air wash input but also has a main air input in the center front of the box right inside of the door at grate level. This air shoots directly into the firebox at grate level (the grate is in the floor of the firebox and above the ash pan) and can be seen to burn holes in wood that it hits or burn away coals if coals are what is there. Raking coals to the front of the firebox near the glass door burns them away quickly. Of course I'm talking hardwood because the pine and poplar I've been burning this year doesn't make many if any long term coals.

My stove does not have an air intake there. All the primary air comes in as doorwash, but the effect is the same - it blows right in at the front edge. No grate either.

 

[Chris-PA]

That's an interesting question... and I'll tell you why.
During warmer weather and reduced draft, like the last few days, the firebox work pretty darn good, and when I clean the ash out it's super fine, light weight and whitish in color.
But during cold weather and increased draft (even when I purposely fiddle with the coal bed every half hour to get it to burn down) the ash is course, heavy and dark grey-to-almost-black in color (and full of un-burnt, small charred pieces of coal).
Not really sure what that tells us though... other than lack of enough oxygen.

Would burning in a high velocity air flow do that?

 

[Whitespider]

By the way spidey, I just looked up the Daka furnace manual, page 7, and I quote
1. A barometric regulator should be installed in smoke pipe...

Yeah, I know it says that... but on page 2 it says...
"4. A barometric regulator/damper may be used in the chimney connector..."

If I need one... then I need one... but I'll try it with a flue damper first.

addendum; See, the way I read page 7, after reading page 2...
"1. A barometric regulator should be installed in smoke pipe at least 18" from furnace..."
... is to mean, if a barometric regulator is used, it should be installed 18-inches up the pipe.
But maybe that's just wishful reading...

 

[Whitespider]

Would burning in a high velocity air flow do that?

I have no idea!

 

[brenndatomu]

Yeah, I know it says that... but on page 2 it says...
"4. A barometric regulator/damper may be used in the chimney connector..."

If I need one... then I need one... but I'll try it with a flue damper first.

addendum; See, the way I read page 7, after reading page 2...
"1. A barometric regulator should be installed in smoke pipe at least 18" from furnace..."
... is to mean, if a barometric regulator is used, it should be installed 18-inches up the pipe.
But maybe that's just wishful reading...

Ahh, well in light of page 2 you may be right

I hate when a manual gives you several different specs on the same subject! I have seen in other furnace manuals where they can't even seem to make up their mind on the draft setting that they want you to use!

 

[laynes69]

Spider, I found a thread recently with a man with the same stove as yours. He installed a smart stove electronic controller. Before he calibrated the controls, his stove would reduce a full load to ash within 4 hours, flue temps hitting over 1000 internal. After calibrating he said his stove runs normal or a little better. He loads it and within 4 hours it's coals then 4 hours later he reloads. No excessive coaling, and plenty of heat for the home. I don't know about his setup, but if he can reduce a load to ash within 4 hours there's a very strong draft.

There's many threads with those with excessive coaling, and lack of heat output comes along with most. On a mild day, your stove/furnace did just fine. It was able to burn down the load and meet heating demand. Once it would get cold, that coal bed was no longer enough to keep things warm. If you can't wait for the coals to burn down, your forced to add more wood which compounds the problem.

I don't know if you tested the draft with a manometer. I thought our old chimney 7x11 32' had excessive draft, but when tested the draft was extremely weak, once hot though it was too strong. The liner solved this problem with a constant strong stable draft.

Unless your stove had a defect, the other poster had no issues burning down a coal bed. That leads me to believe the draft may not be what you think. Its not your wood, but probably a combo of draft and the home. We had very poor performance, even with our 32' chimney before lining with a 5.5' stainless liner. The old furnace on the other hand had no issues with the old chimney

 

[stihly dan]

Spidey, try the bdr on the daka first. you won't regret it. It will help in 2 ways, constant even draft for warm or cold days. windy or no wind. also taking some basement air cooling the chimney SOME which also helps keep the draft down. Its not like the bdr is wide open sucking air. You probably used more extra combustion air on your stove than the bdr would have let up the chimney. So loss of basement air would be a wash.

 

[brenndatomu]

Spidey, try the bdr on the daka first. you won't regret it. It will help in 2 ways, constant even draft for warm or cold days. windy or no wind. also taking some basement air cooling the chimney SOME which also helps keep the draft down. Its not like the bdr is wide open sucking air. You probably used more extra combustion air on your stove than the bdr would have let up the chimney. So loss of basement air would be a wash.

This was true on my old setup using a external SS double walled 6" chimney. Not so with the setup I have now. (8" insulated SS liner in my brick chimney) During a real cold spell here recently, I noticed the BDR layed out wide open, and the draft was still -.04" WC! (as I said earlier, it usually runs -.02" to -.03") Don't think there wasn't some airflow happening there! You could actually feel pretty good breeze between the make-up air pipe and the BDR opening!

But I gotta agree with Dan there spidey, I think if you give a BDR an honest open minded try, you'll like it. Or at least do like layne69 said, get a manometer and run it on your stack for a while, you may be surprised what you'll find, but at least then you'll KNOW exactly what you are dealing with, with numbers to prove it.
Heck, you are some kinda tech, right? I'd think you'd jump at the chance to play with a new test instrument! I know I did, I mean it was only $20 delivered to my door. (fleabay)

 

[Whitespider]

On a mild day, your stove/furnace did just fine. It was able to burn down the load and meet heating demand. Once it would get cold, that coal bed was no longer enough to keep things warm. If you can't wait for the coals to burn down, your forced to add more wood which compounds the problem.
That leads me to believe the draft may not be what you think.

Ohhhhh please, can we not go back there... please take the time to read every single post in this entire thread.
It's not as simple as less heat than needed to heat the home. If you had read all the posts you would understand that, and never posted the above.
When the stove is several inches deep in coals, I can lay my hand on the bare steel of the stove!
The problem is not lower that required heat output, the problem is absolutely no heat output at all! None! NaDa! Zip! Zelch! Zero!
THE PROBLEM AIN'T POOR DRAFT!!! And that's a fact!

 

[Whitespider]

...at least do like layne69 said, get a manometer and run it on your stack for a while, you may be surprised what you'll find, but at least then you'll KNOW exactly what you are dealing with, with numbers to prove it.

"Prove it" to who? Myself? Obviously I'm not the one needing the convincing.
But there's something I've already stated several times now in this thread...

Guys, the time for experiments is past. The cold weather is gone for another year... THERE AIN'T ANYTHING TO TEST NOW!
With milder weather, my draft is now reduced to a manageable level.
Yes, I can feel and hear the difference... yes, it is reduced significantly... yes, it don't suck the door shut with a slam anymore... yes, it don't create that whistle and howl in the firebox with the door open anymore.
The decision is already made and I ain't willing take the chance some new experiment won't work when January rolls back around... I'm pulling it out and installing the DAKA furnace.
I'm no longer looking for solutions to the current set-up... we're just kickin' the can around.

 

[slowp]

"The Primary Burn zone is initiated from the coal bed. It is the most important burn zone, ensuring that air flows into the heart of the fire."

The primary burn zone in my Jotol F600 is in exactly the same place as show in the Quadra-fire video


<iframe width="560" height="315" src="http://www.youtube.com/embed/Pqx4Nwc8udA" frameborder="0" allowfullscreen></iframe>

That's my stove. I have learned NOT to block that front air intake when putting wood in too. It is a good woodstove for my Warshington Bungalow.

 

[brenndatomu]

You are absolutely correct spidey, it's your party, your opinion is the only one that matters (well, you n the Mrs) when it comes to heating your house. I realize you have made your decision and are no longer looking for solutions, some of my posts are more comment on what others have said here than for you.
Now then, I have spent most of my adult life doing diagnostic/troubleshooting type work, so something like what you have been dealing with here has my full attention, just the way my brain works. If it were my stove, and it's not, I would want to know, just for my own information (knowledge is power) the exact draft #, if I'm replacing the stove or not, just how I'm wired.
I can tell from reading your posts for a year or so now, (which I generally enjoy) you ain't no dummy and I agree with your conclusion about your stove. If it is as windy out there as you say, there is no way you can not have high, and probably erratic draft with a 40' chimney.
I know you are very experienced at controlling that draft with a key damper and I'm sure it will work on the Daka. But for myself that's kinda like airing up a tire by eye, yeah you can get it within 5-10 PSI, but a gauge will help you nail it dead on optimum pressure for best life and performance. My curious mind would want the gauge (manometer) and an automatic pressure regulator (BDR) for the best performance my stove can give, especially in a tough draft environment like yours.

And for anyone who is interested, a little side note, a couple things I have learned about BDRs over the past year or two that most people probably don't understand.
1. They suck the heat out of your home. Not with an outside air make-up source.
2. They cool off your chimney too much so you lose draft and/or make creosote. If the chimney cools off too much, your draft drops and the BDR door closes maintaining the draft. Also, from what I have read, the reason they don't seem to creosote the chimney up as bad as most people think is, because of all the fresh air mixing in dilutes the smoke. Kinda like the way the auto manufacturers in the 70s and 80s used to inject air in the exhaust to pass the emissions test, they diluted it. I dunno, but I do know my flue pipe after the BDR is pretty cool, but I have great draft and the chimney has some soot, but very little cresote.

Sorry spidey, not trying to derail your thread, just, like you said, kickin the can around. :msp_thumbup: Carry on!