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Post by satamax on Jan 12, 2017 22:11:13 GMT -8
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Post by peterberg on Jan 13, 2017 2:01:50 GMT -8
Mine was run for one season only, but the top barrel has been used in other experiments. There are several effects in play which prolong life of those barrel tops.
First is fundamental, the gases coming out of the riser are oxygen-frugal so there's not much free oxygen to corrode the steel top.
The second is the distance from the riser, in my case almost a whole barrel. The temperature declines with distance because the flames are spreading out and radiating to the steel before hitting the top.
Also, I could see through the bung hole in the top barrel that the flames aren't touching the steel in reality, they're bending away and down along the walls just before that.
And last but not least: only when the heater core is fully loaded and goes into thermal overdrive the flames get that high. More often than not coupled with a higher carbon monoxide content, so it would be best to keep the flames inside the riser.
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Post by gugaiz on Jan 13, 2017 7:38:49 GMT -8
Thanks..
So, I guess having a barrel 30cm away from the riser wont make the barrel last too long... only one season? If so, any ideas on how can a get a bit of "durable" quick radiant heat from the stove. I mean, it will be mainly a masonry heater but I would love to have some instant heat without having to replace a barrel every season.
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Post by peterberg on Jan 13, 2017 7:56:09 GMT -8
Maybe I wasn't clear about this. A steel barrel will last for several years whithout problems. There are examples of 10 years but I don't know about the operating circumstances. That 30 cm is 4 to 6 times larger than the minimum top gap in J-tube style rocket mass heaters anyway.
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Post by matthewwalker on Jan 13, 2017 7:57:12 GMT -8
Hi, great thread! Does anybody know if a barrel will last long enough as primary bell (i.e. on top of the riser)? peterberg says that anything above the riser's lever should be refractory and I was wondering how long will last a bare metal barrel, as I have seen in many configurations. It will last for decades, as long as it can shed the heat. Like boiling water in a styrofoam cup.
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Post by byronc on Feb 4, 2017 8:10:44 GMT -8
If building the bell out of masonry, the section above the riser needs to be refractory. If using a steel bell / barrel, that rule (obviously) does not apply.
Many RMH builders have replaced their stoves steel barrel at the 20 year mark, only as part of general maintenance, and then found that their old barrel was in fact in excellent condition. From what I remember there is one RMH still in use with its original 30 year old barrel.
Went to a lot of trouble to clean my barrel down to the bare metal on the exterior surface, and then painted it with 1200° F. stove black. To help keep the painted surface in good shape I try to avoid over firing the stove. That usually means avoiding stuffing the thing full of super dry small "kindling" size sticks. Loading just a few kindling sticks then jump to 2 to 3 inch diameter seasoned wood for the remainder works best for my stove.
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Post by matthewwalker on Feb 4, 2017 9:15:36 GMT -8
Byron, overfired rockets run cooler.
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Post by byronc on Feb 4, 2017 13:58:24 GMT -8
H'm, maybe I'm using the wrong terminology Matt? This stove is an odd arrangement of a 6" batch, 8" mass ducting, to 13 feet of completely vertical 6" insulated class-A chimney. It can draft like mad getting way to hot to quickly, depending on how much and what size fuel is loaded. I've been burning seasoned maple, ash, beech, and using cherry branches split up for kindling.
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Post by matthewwalker on Feb 4, 2017 15:02:27 GMT -8
Can you see your chimney during those times Byron? If you see dark smoke, it's what I call overfueled. That violent burn in the box creates more gas than the available air can combine with to combust, and you get black smoke. That's why "overfired" is actually cooler on the barrel, because you are overfueled and it's not as hot as more balanced combustion.
If you don't see dark smoke, then it's working as designed and the hotter the better, in terms of efficiency and burning true to design intent.
That's not to say I always burned my J at full tilt, but I did when I ran the Testo. Same as Peter and his batch test runs. They are terrifying. If you are scared, but there's no smoke, you are doing it right.
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Post by byronc on Feb 5, 2017 4:39:47 GMT -8
No, there's no smoke out the chimney, the burn is lean and hot. I only get a bit of steam at times which completely vanishes within about 6 feet or so of the chimney cap. The stove works great, is very easy to light, drafts straight away, and the "afterburner" lights off immediately from a cold start. In 35 years of heating with wood fuel, this stove is the best I've ever operated. It's one lean mean heat generating machine.
Have you ever burned seasoned Ash, Matt? The stuff burns super hot, like it's impregnated with gasoline / petrol. I once scorched (turned white) the 1200° F. stove black paint on the top of my steel barrel, and had to open several windows for fume ventilation. That's on a 750° F seasoned stove blackened barrel. Since then, I no longer burn full loads of Ash, nor Maple, but rather only 5 to 6 lbs. of it mixed in with a greater quantity of softer less energy dense wood. My area is heavily populated with hardwoods, so it tends to be the fuel of choice. There is some pine and cedar available too.
The heat riser for this stove is built from 2600° F rated IFB, following Peter's 6" batch in brick layout. There is 21 inches of headroom between the top of riser to top of barrel.
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Post by matthewwalker on Feb 5, 2017 6:27:36 GMT -8
I haven't burned ash Byron. I can say I was terrified when I saw the first load of dry, small oak go in the stove in DC. I am used to much cooler softwoods. Still, the fact remains, rockets are rockets because they should be run as hot as they can get. Period. The hotter the better if you are going for efficiency. To get in that 80% range you have to be scared, it needs to be maxed.
Adiel, or perhaps Shilo, said it the first time I heard it, and they are right. Overfired rockets are cooler. If you can get it hotter, you can be more efficient.
Again, I get what you are saying. I rarely burned my J like that either, but not because I was fearing for the materials. It just is too hot for comfort in many cases.
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Post by byronc on Feb 6, 2017 3:25:17 GMT -8
I'd like to have seen that test rocket burning oak. There is some oak seasoning out in the woodshed, but it's another year or so out before it'll be ready. However, years ago comparing oak to ash in my high efficiency box stove, oak burned cooler and generated greater "coaling" than ash.
My indoor rocket (6" batch) roars like it should, i.e. roar like a speeding steam locomotive, and on occasion goes into high frequency pulse mode. Damn cool, and I'm not easily impressed, except raging forest fires, now those things do scare me:o)
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Post by pinhead on Feb 6, 2017 6:01:41 GMT -8
If you want heat, load your batch box up with seasoned hedge splits. I've had the entire barrel above my 7-inch Batch Box glowing red with a full batch of hedge. I had to put a box fan in the door to cool the shop with 10°F outside air in order to keep the rafters above the stove from spontaneously igniting. I literally ran around the small shop with a squirt bottle full of water, spraying down any wood that was within 5 feet of the stove. Then again, it may be tough to get wood like I was using - "seasoned" is an understatement; these were 50-year-old hedge posts that had shrunk down to about two inches across.
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Post by byronc on Feb 6, 2017 13:27:45 GMT -8
That's mighty hot, which begs the question. What shade of cherry red was it?
Dull red is about 1300° F.
Dull cherry red is about 1500° F. Full cherry red is around 1700° F. Clear cherry red is around 1800° F.
Orange, somethings fixin' to fail in a bad way:o)
No doubt about it, cherry red steel of any flavor is just plain hot, any way you look at it.
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dkeav
New Member
Posts: 27
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Post by dkeav on Feb 6, 2017 15:26:34 GMT -8
Should clarify that "Hedge" is midwest slang for Osage Orange. It supposedly has the highest BTU of any common hardwood. Is overly abundant in the middle US as it was used after the great dustbowl for wind breaks. It isn't much good for anything other than fence posts and burning, but wow does it burn hot. source
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