Diary of a 600 degree burn

By request from Browning BAR, here's notes on a 600-degree stovetop burn in the Ideal Steel.
About 15 degrees outside and falling, 10-20mph wind gusts.
Stove started at 350 stovetop, with ample coals (3-4" deep).

Red Maple and a couple of Ash splits, small-to-medium sized (luck of the draw, no large splits this load).
I was the first one home from work, so the house was cool (daughter fed the stove a little, mid afternoon), and I wanted a quick fire. Raked the coals, placed on small split N/S on the far right side of the stove, and then the rest of the load E/W (this allows air in under the load for a faster start). Loaded up to within 2-4" of the top (no big holes, but some). Flue probe is Condar, single-wall pipe. Stovetop is on left side and the right side runs a little hotter, but the mag thermo runs a little low as per IR (that I no longer have).

OK, apparently no html table support, I'll try to make this readable...

Columns are Time, Stovetop, Flue, and Observation or Action

0:00:00 350 350 Load, Damper wide open
0:02:15 350 400 Damper to 80%
0:05:50 350 500 Close bypass
0:08:40 350 575 Damper to 60%
0:11:30 400 600
0:13:05 450 700 Damper to 35%
0:15:00 500 725 Damper to 20%. No flames at front of load.
0:18:30 550 625
0:22:00 560 600
0:23:40 570 580 Damper to 22%
0:25:40 575 600 Floating/drifting flames across front of load
0:30:30 580 600
0:34:20 600 600
0:44:00 600 600
1:01:00 600 590 Front top split collapses into andirons (+4" triangular piece)
1:15:00 600 600
1:21:00 610 600 Load has lost one third of its height. Strong secondaries.

 

Nice chronological timeline and research variables there, that which only wood hoarders would validate!

 

1:30:00 610 600
1:40:00 610 590
1:45:00 610 510 A room thermo on a chair 5' from the front glass reads 99.1
1:55:00 600 500
2:00:00 575 450 Still some secondaries, gray ash on the front log. I can hear the teapot slowing down.
2:05:00 550 410 Damper to 35%. Coals are even with the top of the andirons. Some blue flame.
2:10:00 510 410 Damper to 40%. Slight creaks from the stove.
2:15:00 500 450
2:22:00 500 450
2:30:00 480 440
2:40:00 450 400
2:50:00 425 400
3:05:00 400 350 Damper to 60%
3:25:00 375 400 Damper to 100%. 6" of coals. Very faint blue flame at the back.
3:40:00 350 400 Still blue flames at the back.
4:00:00 350 390 Faint blue flames continue. Bypass opened. Darn coals.
4:10:00 350 350
4:15:00 325 325 Had enough. Fluffing up the coals, reloading, and going to bed.

 

4:23:00 325 325

 

Flamestead, have you checked temps on the middle front of the stove, right above the door, just right of center below the top? With the IR I had stove top temps at 630 just to the right of the flue collar this evening and that spot above the door was hitting 770 on 40-50% air.

When we are burning oak on these really cold windy days I'm often reloading every 8 -10 hours on a huge bed of coals to keep the heat pumping, even sooner if burning the cherry.

This thing is capable of long burns but when the air is on higher settings it can really chew through the wood quick. I say "chew" because the logs on the top of a load under the secondary air plate look like an egg crate after the secondary air chews on them for a while.

 

Interesting.

I would just never do this with the PH.

At you 5:50 mark of 350 and 500, I would cut the air, which would already have been at 2/3 immediately on closing the stove door, down to 1/2 or lower, close the bypass, wait a minute, then close the air to 1/4 if VERY cold out, otherwise to just a crack open.

If to just a crack open, then I would not touch the stove until the fire was down to coals.

If very cold out and to 1/4, then would let the fire burn til stovetop at 435 or so, then close air down to just a crack open. When stovetop fell below 400, would open air to burn down coals.

In either situation, I would have way longer than 5 hours of good, steady heat output on that full a load. And no continual messing with the air.

 

Am I reading this right? It burned through a full load in just under four and a half hours?

 

Yes, the front, above the door, is the hottest part of the stove; this makes sense, given where the cat is located and how the exhaust air is flowing. I've seen temps in the 750 range there.

 

Hi Sherwood,
Are you describing a 600 degree stovetop burn like I was, or simply 5 hours of good, steady heat output (at something less than 600 degrees)?

The PH air is higher velocity than the Ideal Steel, so you can close it more, sooner. I could have closed the air as you described, but that would have illustrated a long, slow buildup in temp, which is not what I wanted. I also would not warm the PH up as fast as I do this steel stove - I don't know how fast is too fast for the PH and do not want to learn that the hard way.

I agree the PH will give a longer/flatter peak without touching the air, due to the additional stone. I don't recall closing the PH air to its final setting at 6 minutes into the burn very often, but can see how it could be done. I made a note last night on my log sheet that I would have felt comfortable leaving the house at the 15 minute mark. I did slightly touch the air once after that to get to my stated objective (generally not so particular about reaching a specific temp).

I could have gone on for quite some time at a slowly descending stovetop without touching the air, but I was up 'till midnight as it was, and I like to go to bed with a fresh load in the stove. As it was, the oil furnace kicked on before I got the bedtime load going.

 

Yes, reload was just about 4.5 hours.

I wasn't too proud of that load of splits. 1) Red Maple, 2) more finely split than usual, 3) no big pieces for the very back, 4) onto quite a few coals, 5) closer to 19" than 22" long.


My spreadsheet says to expect 2.3 cu ft of Red Maple burned at 80% efficiency in 4.5 hours to generate on average 60 BTU/hr.
-Red Maple is good but not great
-I likely had less than 2.3 cu ft (4" of coals * 22" * 18" = 0.91 cu ft at both ends of the burn), and take off another 0.4 cu ft for using 19" wood.
-It likely was lower efficiency at times due to the higher stack temp

Generating a lot of heat consumes wood. Both this stove and the PH at 600+ degree stovetop is a lot of heat. The PH's theoretical max output (80 BTU/hr) equates to about 0.7 cu ft/hour of Red Maple (in splits, not one cube).

Opening the air at 2 hrs probably chopped quite a bit of time off the tail of the burn. But I wanted to go to bed with a full firebox, so I didn't really care about dragging out the burn with a cooling down stove. At its hottest, the stove was not overheating the house - generally whoever is closest to the stove is spoken sharply to if it reaches 350 degree stovetop on a cold, breezy day.

I can do a re-do, with a weighed and known moisture content load at some point in the future, to eliminate some of the assumptions that went into my calculations above.

 

When we were burning hot on really cold days, on higher air setting, we did burn through some full loads of a combination of cherry and white birch and reloaded in 5-6 hours on a huge bed of coals, to keep up the heat output. Burning a full load of the oak blocks now on these really cold windy days, on higher air settings, we are reloading at 8-10 hours.

 

Hi, Flamestead,

As stated, and it was just for a comparison, I would not burn the PH at 600. Would get it to 425, maybe 450. With that much wood, it would give a great deal of fairly steady heat for a lot longer than 4 or 5 hours. Burning the PH the way you are burning the Ideal Steel (I realize that burn had unusual parameters for you, ie small splits), I know a lot of heat would be lost up the chimney , if I could even get the PH to a stovetop temp of 600.

A point was also that, in the setting of a warm stove, I find the PH really quick to light off (before the door is closed), and very swift to operating temperature, at which point one adjustment is generally made and the stove can be ignored until reload time. Just don't do the adjusting, unless I have guests and want a fireshow mid-burn, or some such situation.

I warm the PH quickly, and never worry about it unless the stove has not been used in a LONG time, in which case I treat the soapstone as if new. But my warm up may not be yours. My stove simply does not want to burn at 600. It is rare, and takes a concerted effort, for my stove to get above 450. AT 450 it is pushing out a great deal of heat.

I don't burn with very full loads. If I load 2/3 full and want a stovetop of 525, I can get it. But the stove wants to burn a bit cooler, and is very efficient when doing so, while still producing plenty of heat, at least in my setting.

I understood you were deliberately burning with a hot, rapid heating fire, with small splits. I was still surprised, with the bigger firebox and almost full, that the stove burned the load in somewhat over 4 hours. If the wood was 2 -3 inch rounds, I guess I understand...that would leave a lot of air space, and have lots of surface area to burn. Must have been some fire.

One man's small split may be another's medium. Always a bit of guessing when contemplating someone else's fire.

Anyway, wasn't meaning anything as criticism, just as comment and comparison. Most of my point was that the IS can be and is burned quite differently than the PH.

 

Hmm. That's no different than the 30.

 

No one questions that the 30 is a good heater.

BTUs are BTUs. Cubic feet are cubic feet. There are no magic stoves. To get high BTU output over long periods of time you need a really big firebox with good air control that doesn't send all the heat up the flue. When you need high heat output you can burn through a lot of wood quickly regardless of the stove.

I think the difference is the ability to go really high and hot as well as low and slow with the hybrid on low air settings.

But if you need really high output and long burns you might need to go with the biggest Blaze King you can get.

 

Let me elaborate on that.

This wasn't a knock against the Steel or that the 30 is better. I was just surprised that the Steel, at 600, had the same burn time as the 30. I would have thought it would have been a bit more efficient and provided 10-14 hours of heat with a peak temp of 600.

This is all about what I need and making sure my next stoves meet my specific needs.

 

Is that physically possible? The NC30 advertises a 3.5 cu. ft. firebox, to the 3.2 cu. ft. firebox on the IS. On a high burn, both stoves are primarily cranking out the high BTUs via the secondary air. The cat on the IS cleans it up but the BTUs are coming from the secondary air on a high burn, right?

Given the BTUs available from the same load of wood, I don't know how the IS could go 10-14 hours of heat with a peak temp of 600 if the NC30 can only go 6 hours on the same amount, or just a bit more, wood. I suspect the IS firebox design will wring out as many BTUs as possible but that's probably just a couple percent more at most on a high burn compared to other modern stoves.

 

With peak temps of 650-750 the 30 can maintain temps over 300 degrees for 7-9 hours and temps of 250 or more for 10-12+ hours on a full load.

I just figured the Steel, being a cat, being more controllable with less heat going up the pipe, would have been able to maintain temps over 300 for 10-14 hours when peak temp was 600 degrees.

 

Hmmm - I can see I need to mellow out a bit when I get home from work before writing here -- my sincere apologies for being a bit prickly.

OK, so I've run the PH for about 12 cord, and have run it quite a bit at 600 (700+ once, early in ownership, scared me a bunch!). Both the PH and the Ideal Steel consume a bunch of wood to reach and hold these higher temps. And they throw a lot more heat at 600 stovetop more than they do at 500 stovetop.

My hypothesis is they throw considerably more than 20% additional heat at 600. I think there is a lot more coming off the front of the stove at the higher temps, but I'm not able to demonstrate that very well. In order to throw that additional heat, burn time suffers, probably at a rate directly (linearly?) associated with that BTU output that we'd love to measure but can't.

The PH air at start-up and during coal disposal is great, but don't try the Ideal Steel's air on a long, slow burn because you will not be able to look the PH in the eyes and tell her you love her just as much as the day of your first fire together - in the back of your mind you will be picturing her but with the Ideal Steel's air control, knowing your relationship could be just that much better.

All the best - Sam.

 

Yeah - I need to re-do the test and leave the draft alone on the downside of the peak. Sounds like a test for a warmer Saturday morning.

Normally, when I'm around, I'm opening the air up as she cools off, because we want the heat and have plenty of wood.

Do you hit the peak as early as I did, or do you ease into it more slowly?

 

Watch the needle on the thermometer on this 16 hour burn again. Subtract 100 to 130 for stove top temps. I think that pretty much fulfills what you just described, no?