Vortex Stove

[Vortex]

Jan 7, 2020 7:05:56 GMT -8 Dan (Upstate NY, USA) said:

Best air ratios seem to be full primary and secondary (each 10% CSA) up until the flue temperature peaks and starts to fall, then 50% primary, close secondary and open tertiary (through ashbox) about a quarter (1% CSA).

That seems like a lot of baby sitting.

Any way to get the same results without all the fiddling?

It sounds more complicated than it is, in practice that's just one adjustment of the air vents mid burn. I think even you could manage that Dan

Ideally the amount of air needed by a fire over the whole burn cycle would probably look something like a bell curve on a graph. How do we provide that without a lot of 'babysitting' - Thermostatic Bi-metal Coil Spring maybe - and if we don't accommodate the air needs, won't the excess or shortage of air lead to more CO and lower efficiency?

Jan 6, 2020 15:03:23 GMT -8 Jura said:

My Lord!

Not so long ago I have learned the word "impeccable" - and I may use it with regards to your last chart- I believe

After I got know You got the Testo I was almost sure I'd see this statement : "Next I plan on making slight changes to the afterburner everyday to see if and how it effects the results. Will let you know how that goes" one day.

You have joined the "experiment upper Circle" .

I wish I had testo, too..

Thanks for being the cutting edge.

Hi Rafał, Thanks

Believe me I've been itching to start experimenting with different afterburner configurations since I first got the testo.

Unfortunately the more complex a system, and the more variables involved, the more difficult it is to get reliable test results. So first I wanted to establish a good baseline to work from. To do that I needed to know what effects all the possible variables and combinations have; Like different wind conditions, types of fuel and ways of loading, and various air ratios at different stages of the burn cycle, etc. and the best that can be achieved under those conditions.

[Dan (Upstate NY, USA)]

I can manage that, but the handicap people I live with would not remember, or lose track of time... No worries...

[esbjornaneer]

Nov 25, 2019 7:22:30 GMT -8 peterberg said:

Hi Trevor, keep in mind that in the last stage of the burn, being coaling phase, it's nearly all pure CO that's produced.

peterberg please would you explain the 'coaling phase' and how to detect it during a burn? You have said in other posts (if I am remembering correctly) that you stop the Testo measurement as the 'coaling phase' starts. Is there a value from the Testo that can be used to quantify the beginning or is it just a visual?
Many thanks, Esbjorn

[peterberg]

Jan 15, 2020 3:28:04 GMT -8 esbjornaneer said:

peterberg please would you explain the 'coaling phase' and how to detect it during a burn? You have said in other posts (if I am remembering correctly) that you stop the Testo measurement as the 'coaling phase' starts. Is there a value from the Testo that can be used to quantify the beginning or is it just a visual?

Coaling phase is easy to see, all yellow and orange flames are gone and a pile of glowing charcoal with faint blue flames remains. You've seen that happen or otherwise you didn't burn any wood before in your life. So I am inclined to think you are pulling my leg and ask questions just because you like to do that. When that's the case, I won't answer your questions anymore.

Therefore, the following might or might not be the last answers you'll get from me.
You're wrong here, I never ended the test runs at the start of coaling phase. At first, following the method of the Masonry Heater Association, I used the point where oxygen comes back to 90% of normal environment level.

Years ago I found out the end of the run looked always the same with a rise in CO. Later European tests protocols chose another point: when CO² comes down to 4% or 25% of the highest level of CO² during that burn. Incidentally, that point is usually well into coaling phase. So I used that, a fixed point suitable for to compare results and skipping the uninteresting ends. All my tests were terminated at this point since 2009, if I recall correctly.

Beginning of coaling phase is hard to pinpoint by an analizer on its own, since the CO starts to rise (and CO² comes down) in the chimney stack some time after the visuals are there. That time isn't a fixed amount.

And last but not least: since you don't have a Testo analizer this information is of no value to you, so why on earth do you want it?

[esbjornaneer]

Thank you for the detail in your answer Peter.
I did tell you back in October that my Testo had arrived.

[peterberg]

Jan 17, 2020 0:06:04 GMT -8 esbjornaneer said:

Thank you for the detail in your answer Peter.
I did tell you back in October that my Testo had arrived.

In that case please forgive a grumpy old guy, maybe I need to get worried about Alzheimer's.

Additional information: CO and CO² is a balancing act, less CO means more CO². My test runs start when lit, and end at 4% CO² as mentioned above. I've chosen a consequent layout for the graphs so those are comparable, helped by the averages of O², CO, T and Efficiency.

[esbjornaneer]

I forgive you.

I don't remember seeing CO2 ever in your graphs. I'd be very interested in seeing how one of your graphs look with it included. My max CO2 so far is 12.95% which sounds low to me, but when testing a DSR2 core I only got 7.35%CO2 as the peak value, so not sure of reasonable range here?

But maybe this is stealing the tread...

[Vortex]

CO2 seems to have an inverse relationship with the O2. 4% CO2 corresponds to 17% O2 on my recent graphs. CO2 is in yellow using the 0-20% O2 scale:



It takes about 2 hours for my burns to get back to 17% O2 / 4% CO2, by which time there is almost no coals left. In the graph above I had to go out for an appointment so re-opened up the primary air at 98 minutes to see how quickly it would go up.

[Jura]

Mr. Peter Van der Berg said a few post ago:
"In a "normal" box stove the CO goes up when O² comes down, in an afterburner construction both go down the same time provided combustion is commencing the right way"..

It seems your afterburner works perfectly well...

btw. waht kind of Testo you have (that is equipped with CO2 sensor?)

[Vortex]

Thanks, I was looking for that quote and couldn't remember where I'd read it, and exactly which gases Peter mentioned.

The analyser is a Testo 330-2 LL. It also measures draft.

[esbjornaneer]

Ah, thank you for your reference figures and graph. I have also just found in the Testo330-2LL manual: Wood CO2Max 20,3 Vol.%, O2Ref 13 Vol.%. So I guess we can not go above that anyway

[DCish]

Hi Trev - day job's been busy, so I haven't had the luxury of checking in for quite some time. Glad to see you got the testo graphing, it's been a pleasure to catch up on your thread!

[patamos]

Nice work Trev

Great to see your graphs/numbers so dialed in.
This adds to a growing body of evidence for a tightly loaded top down burn with side air intake - at least in relatively large firebox configurations.
Interesting to see the effects of closing bypass well into the ramp up phase.   This has convinced me to open my bypass only 10% or so for a few minutes on start up. With a good nest of tinder and kindling the burn is clean from the get go...

[Vortex]

Hey Pat, Good to hear from you    

Are you running the same stove setup this winter?

I was surprised how big the CO spike was from just closing the damper. Fortunately since changing over to that new low resistance chimney cowl I don't really need a bypass damper much anymore. Only time I use it now is while I'm lighting the tinder and kindling, as soon as I close the door I close the damper. I've even thought about making a mechanism to connect the door to the damper, so it automatically opens and closes with the door.

What do you use for tinder? I had a load of wood shavings which were brilliant but I've run out now. When lighting from on top with paper and cardboard it seems to smother the kindling in a thick layer of ash. I think traditional tinder was dried moss, we have tons of that here but I've never tried it.

Jan 31, 2020 21:27:17 GMT -8 DCish said:

Hi Trev - day job's been busy, so I haven't had the luxury of checking in for quite some time. Glad to see you got the testo graphing, it's been a pleasure to catch up on your thread!

Hi Brian! Great to see you back on the forum again. Well done for repairing all those image and video links in your 'Adding a bell/bench to the flue path of a standard box stove' thread .

[cork]

Hi Trev,
In reducing the gap between shelf top of the after burner and the hot plate above was the restriction added on the shelf or to the hot plate? I assume the measurements down stream of this are flexible.