Woodstock Absolute Steel - How to burn slow and low

Thanks to all the helpful responses to my earlier post, I've learned how to get my stove fired nice and hot, with STT up to 600+, or at least hot enough to get my catalyst lit. Now I could use your help figuring out how to maintain a long, efficient burn that can go overnight without frequent adjustments.

Right now my fires tend to be all or nothing. Once the firebox and catalyst are hot enough, with any excess moisture sufficiently driven out of the load to maintain a catalytic burn, the stove tends to burn through the gasses rapidly (2-4 hours max) with secondaries burning brightly, before dropping below the catalytic burn zone and cooling off until I have to open the air control all the way (and often the door a crack too) to burn down the bed of large, chunky black coals.

It sounds like many of y'all are able to maintain a catalytic burn for much longer than this with the firebox mostly dark. Once the cat is engaged and secondaries are burning brightly, mine don't want to go out, even if I turn the air control down to 1 or 2 small marks (fractions of the 1 position), until they've apparently burned through all the combustible gasses in my load. (I'm actually a bit worried about whether I could snuff out a fire if I needed to, given the apparent unresponsiveness of this secondary combustion to any air control input.) And once the secondaries finally do burn out, the air is throttled too low to allow the coals to continue to burn down much until I open it back up again.

Can any of you Woodstock experts advise how to find that magical dark burning zone that will more slowly and steadily consume the energy in my fuel, ideally with enough air intake to allow the coals to keep burning when once the gasses are used up?

Thanks again!

FeelTheBurn

 

The secondary air has it's own control.
It hidden behind the back cover and is not adjustable. it's a bimetal tab and opens when the firebox gets to the right temp. so you can't "shut it (secondaries) off" completely.

 

If you'd like, you could give me a call.

 

Hmm, so once engaged do the secondary flames become entirely self-sustaining and beyond operator control for as long as there's sufficient fuel remaining and they're injecting enough heat into the firebox to release it? And if so, is there any danger that this fire can run out of control and overfire the stove, or in the case of a chimney fire, prevent choking it off? I like the idea of a self-regulating air intake, but it concerns me that there's no way to manually shut down a fire in the stove in an emergency.

 

Mine will usually go black if i cut the air back far enough.

 

Same as turbo.. but mine IS not AS.. I have been running stove for 3 years and its never run away on me. It does low and slow really well.

 

Good to know. In an emergency, maybe shutting my air control lever all the way to "zero" will be enough to snuff things out.

 

What does low and slow look like on your IS, in terms of time in catalytic burn, STT, cat temp (if known), presence of secondaries, and air control setting? Mine may not be in actual danger of overfiring, but I definitely haven't figured out low and slow yet either.

 

I don't often use the low and slow. Heating from the basement takes a bit more heat. and I don't like burning down the coals at the end...

 

With my IS, I am burning 15% MC wood, I only have 2 thermostats Stack and stove top. I know I am burning efficiently when I get ghost flames. I get stack thermometer to 275 single wall so double it. Engage cat andCut air down from full to 3/4 to 1/2 to 1/4. In about 5 minute intervals. Then for me to second notch. Stove goes dark for 5 minutes then poofs of flames. Turn air down just a touch, the ghost flames, flames just dance middle of glass. Disappear and re appear without touching anything.
When shutting down STT get to 600 and usually cruise slowly down 300.

 

If you have cat probes and want real time graphs for low and slow.
Search thread for Ideal Steel tips and tricks posted by member BDF

He has IS, I read stoves are very similar, AS just size smaller. He, Brian, bdf, has a 4 probe digital recorder that measures Stack, Stove top, cat probe and Firebox probe in chart form. I imagine your temps would be similar with 20% less or so times due to the 20% smaller fiebox

 

I'll have to check that out. I'd love to be able to digitally monitor, record, and remotely monitor/act on the cat temp data.

 

My cat burns are quite similar.
I have cut the air down to 10 or 15% notch and got close to 800* STT

 

No, with the control at zero there is still a small amount of air getting in. It will get a hot fire under control (eventually) but not snuff it out.

 

Mine burns much the same. I load at around 2100 hours, and load in the morning at 0730. By that time, the cat probe is almost at 550 degrees. Every set up is different, but I shut down to .75 below the 1 setting.

Are you burning a full load of fuel OP?

 

Not stuffed completely tight, but a good sized load, usually about 6 medium sized splits and maybe some smaller kindling, on top of a thick bed of coals.

Remind me, are you using an IS or an AS?

 

I just reloaded my AS.

6:10 I raked the coals and spread them so that there was a large pile near the door, and an equal pile near the back. Leaving a small valley in the middle completely clear to the grates. Then I opened the ash door and burned down the coals for 5 minutes.

6:15 I loaded the stove with ash. You cant see it, but theres a split in the top left corner too. I had good flames before I was finished loading it. Then closed the door.


6:15 500F STT shut the ash door and bypass in that order.

6:20 I throttled back to 3

6:30 throttled back to 1.5 STT settled to 480F it will sit there for a bit until the secondaries start firing, then the temps will climb a bit, and I will shut the air down to .75 (or I could do that now if I was going to bed)

 

AS. I pack her tight, but leave the door cracked to get flue warmed back up. Then close the door and wait until the SST is 350 or above before engaging the cat.

 

Mwalsh - when you get up in the morning, will your stove have cooled down a lot? I've been following a similar approach as you, and with the air shut down below 1, the stove seems to run along at a steady temp until it exhausts the gasses and smoke that fuel the catalytic burn. Once those are exhausted, though, the low air intake at that setting seems insufficient to burn down the remaining char, so the stove temp drops quite low until I get up and open the air back up.

I'm wondering if there's a sweet spot for the air setting and the timing of cat engagement where I can get a long slow catalytic burn while the fuel is off-gassing combustible fumes, but have enough air coming in to keep the coals burning a little better once the gasses have burned up. I'm going to experiment with engaging the cat before the stove heats up so much and see if that allows me to get a long slow catalytic burn at a high enough damper setting to keep the coals cooking once the gasses have all been consumed.

 

Your AS will cool down towards morning, when I get up the cat is way down low. Running at 500 or not at all. Won't hurt to sleep in with the cat engaged. (Down on the AS) I always have plenty of coals to reload. My house is still 72 to 75 depending on outside ambient temp.
Don't engage your cat until your stove top is HOT. The cat probe means little to myself. You will get your stove dialed in, keep at it.