Why would this burn better than a basket full of pellets in the stove?

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Dont know, what would a load of pellets do piled onto a bed of hot coals?? A smoldering mess?? a uncontrolable inferno?? Dont know,
 
From what I read it doesn't work well. Kinda like a pellet stove without the blowers going. If they could get it going well it would be great.

Matt
 
i'd guess the extra suface area of pellets would allow better heat penetration resulting in excessive gassification for the available amount of combustion air which would result in uncombusted CO up the chimney & inefficiency
 
This is the stuff I burn. I assure you it works better than pellets in a woodstove -- although I've only tried pellets in a heap, not in a basket, but I hear they don't work too well either way. It's basically identical to BioBricks, in fact these were probably manufactured with the same brand of machine that makes BioBricks. Search the reviews--I think it was BeGreen out in Washington state who had a shipment of BioBricks sent out and he reviewed them. They burn this stuff over in Europe a lot supposedly.

From my own comparisons with kiln-dried hardwood ("HotSticks" from a nearby logging company in PA), the WoodBrickFuel tends to burn slower than normal splits, but last a little longer and the resulting ash seems to be more grey "ash" and less "random black unburned bits of char" that I noticed with typical splits. It's expensive compared to normal cordwood but it's a good fit for me -- my property doesn't have a good place to store firewood, but I have 2 old smoke dragons and the woodbrickfuel did a remarkable job heating my house last winter (with the old Vermont Castings Defiant II, it would practically run you out of the living room). As far as cost though, it's one I'm willing to accept b/c the quality of the heat is much better than relying on the 'ole heat pump, and I think its cost effectiveness surpasses the heat pump when it's below freezing outside anyway. Or comes close. My wife absolutely loves it either way ;-)

The one time I experimented with a heap of pellets in that upstairs stove, I think it just smoldered until it went out. From what I've read about wood burning and moisture content, the problem may be that pellets are way too dry, they smolder too fast and effectively put it out. Of course it's hard to say what they'd do if you dumped them on a pile of hot coals--might have a greater chance of igniting, and then it probably would be an inferno. The closest comparison I have is pallet (shipping skid) wood--I burned plenty of that in the downstairs (Jotul 8) woodstove and while it had no trouble igniting, it smoked a LOT and I could see it billowing over the front lawn as well as the stove glass became pitch black within 15 minutes or so, clearing up after about an hour. I'm guessing pellets would do the same. Pellets really need the tuned combustion air and exhaust flow of a pellet stove.
Woodbrickfuel in that same stove downstairs, btw, made part of the stove glass slightly caramel but it never darkened the glass pitch-black. This old stove doesn't have any form of "airwash" so I'd imagine the results would be much better in a modern woodstove.

Ok so seriously I'm not a salesman for these guys, just a customer with a whole winter season's worth of experience behind me using this.
 
Im pretty new getting back into burning stuff and really, the idea of Bio Bricks or a pellet stove didnt really appeal to me. If good wood were un-obtainable the bricks would probably get a little more appealing but luckily that hasnt occured.

I know there are some places where the cost of quality wood to burn is really high and the bio-bricks are probably even a better option

For example in the add, $249.00 for a ton of the bricks, If storage was a problem or good wood was difficult to track down or expensive....to me thats a pretty good option
 
If that little stack = a cord I dont think i'd want to burn over 1 brick at a time or it would cook me out of the house and that brick would have to burn a long time.
 
Each brick was 2lbs. They are saying a ton of their bricks is more than equal to a cord of wood. I wonder if wood or brick would give more "btu for the buck" if they were both priced the same... $250 a cord or pallet of bricks

Working out their math, 7500 btu/lb *2000 lbs=15,000,000 btu/ton. 15mm*.90 (10% moisture content) would give you 13.5mm of useful btu per cord, not counting the inefficiencies of the stove.

They are comparing their product to "The best seasoned hardwood." Would a theoretical cord of white oak qualify? Not the highest on the btu chart, but not a slouch either. A quick search showed 28MM btu/cord, but it was off an unknown site. The Chimney Sweep is showing 25.7MM btu. Should we say 25% moisture content for our purposes?

So 25,700,000 btu/cord* .75 (25% moisture content) = 19,275,000 useful btus.

Lets play with higher mc... a hissing 35%:

25.7mm* .65 = 16,705,000


Lets try a different wood:

Norway pine at 17.1mm btu/cord

17,100,000*.75= 12,825,000


Are my numbers right, or would you need more than a ton of these things to equal a cord?

Matt
 
"It is made from dry wood of less than 10% moisture content compared to your best dried firewood of 25%. "

H-mmm... maybe I should stop by with a few splits of my seasoned cherry.
 

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Matt Im not sure if you multiply any moisture content like that. I assumed any Btu calcs on cord wood was at a nominal % of moisture (15% 20% ??)

Either way the btu/pound and the "brick" folks saying its equal to a full cord sounds a little optimistic. Considering a full cord of hardwood can go over 2 tons thats a lot of ground for the bricks to make up

And really BTU per pound is pretty equal thru all woods, the hardwoods are just "heavier" per cu ft.

So basicly a "ton" of bricks should equal the btu of a "ton" of just about any wood. When they start mixing volume and weight calculations there just dishing out the sales pitch
 
Battenkiller youre probably going to need to soak that cherry so it will burn right ;)

Seroiusly, thats some nice stuff, I got some cherry held back that I smoke/cook with thats nice and dry like that
 
Battenkiller, I used the 25% number because I figured most people that burn wood aren't going to have stuff at 12%. The stuff I'll be burning was from the big ice storm 2 years ago, but how common is truly dry wood?



Matt
 
Matt I was refering to the moisture numbers you mentioned and how they apply to the BTU rating. Does 25% moisture = a 25% reduction in btu?? 15% moisture = 15% reduction in btu. Just sounds too simple to me and honestly I dont know what the relationship is.

Perhaps it is that simple since were really talking about weight, say a 1lb block of wood at 20%, that actual wood would only be .8 pounds. Of course then you get into the BTU used up evaporating the moisture as well as the lost weight.

Man, Im ready to start a fire, I wish it wasnt so hot..... Is it bad to have a fire going with the AC on???? :lol:
 
One other thing to consider is that in the case of BioBricks, they claim the heat output sticks around (or ramps down) over a longer period of time than typical cordwood--see that one article I posted above about the BioBricks and make note of the graph on the article. I'd prefer to see that experiment validated by at least 1 other 3rd party though. But if there is something unique about the bricks' configuration as opposed to cordwood they might be onto something. However judging by that graph's peak temperature for the cordwood, I'm guessing the cordwood they tested wasn't as "seasoned" as some of this forum members' best cordwood either. Would like to see a comparison between WoodBrickFuel (or BioBricks, or Liberty Bricks, any of those alternatives) and some of the members' best cordwood. Maybe compare the wood pound for pound (weigh the cordwood you're using on a scale before tossing it in) and monitor the stovetop temps over time.

As I stated above, cordwood in my stoves tend to leave a chunkier/dirtier ash footprint, meaning some of the coals didn't burn through completely whereas the woodbrickfuel is relatively clean in its ash profile, so it might be burning more completely. I'm no pyro scientist though so take it for what it's worth.
 
Here is an interesting article discussing the actual btu content, they eventuelly come up with a 6050 btu per pound value for wood with 20% moisture.

That is taking into account the weight of the moisture and also the BTU used to evaporate the moisture

http://mb-soft.com/juca/print/311.html



Spirilis, do you have a good local supplier for the bricks or some place you order from???
 
Yes 2 local suppliers who deliver (both landscaping companies). I end up paying around $300/ton either way though after delivery. I wouldn't be doing it if I had a good place on my property to store cordwood, but, I don't. The woodstoves came with the house, as did the Carrier 2-ton heat pump from 2001 that's barely adequate for the house (my wife hates heat pumps too, the woodstoves feel SO much nicer). So from my perspective, the high cost of woodbrickfuel is worth it as I don't plan on living in this house the rest of my life (it's my first house :) ) so I don't really care to spend the capital investing in something else--like a pellet stove, or a more modern woodstove & chimney setup.
 
ANeat said:
Battenkiller youre probably going to need to soak that cherry so it will burn right ;)

Seroiusly, thats some nice stuff, I got some cherry held back that I smoke/cook with thats nice and dry like that
Click to expand...

I don't have much, less than half a cord for sure. I usually try to keep about a cord and a half left over from last season to get me through the beginning of the season. Got a bigger stove last year, and man is that thing a hungry bugger! Went through 5 1/2 cord compared to about 4 with the old stove, but we're also about 6 degrees warmer on the average, so no complaints here.

I like to mix it in with the less desirable stuff. I always mix wetter stuff in with the super-dry stuff and I think I get better burns than just the dry stuff alone. That's just my own experience, so don't nobody come jumping down my throat saying I'm advocating burning green wood.

Matt, I only mentioned 25% MC because that was the figure the maker of those bricks claimed was the "best" firewood you could get. That figure, however, may very well be the average MC of a full season's worth of wood that actually ends up being run through most folks' wood stoves.


I've been putzing around with the OCR scanning software on my Canon scanner this morning, so here's a page I scanned from my bible, "The Woodburner's Encyclopedia", by Jay Shelton:


Some confusion can arise when comparing lists of energies per cord of various woods because the actual amount of solid wood in a cord depends on the straightness and length of the pieces, and how it is piled. Some authors assume 80, others 90, cubic feet of solid wood in a cord (a cord has an overall volume of 128 cubic feet including the spaces between the pieces of wood). The difference between the assumptions of 80 and 90 cubic feet per cord result in a difference of about 12 percent between reported energies per cord. Actual cords may actually contain from 60 to 100 cubic feet of solid wood. Thus, in practice, there is a very large variability in the amount of energy per cord even for a given kind of wood.

The larger (20-40 percent) discrepancies between some lists of woods are due to the different ways of reporting energy contents. All the wood energies given up to this point have been the total chemical energy in wood as measured in a bomb calorimeter, where the final temperature of the combustion products is essentially room temperature, and where virtually all water vapor generated condenses into liquid water. The heat value measured this way is the high (or gross) heat value. It represents the most heat that could possibly be derived from the burning of wood.

But when wood is burned in a stove or fireplace, the water vapor in the flue gases rarely condenses, especially where the released heat can be used. In fact, such condensation anyplace in the heating system is to be avoided for reasons of safety (related to creosote - see Chapter 12), and chimney life expectancy (due to corrosion). Since the latent heat part of the energy is essentially unavailable for heating, its contribution is frequently subtracted out from the high heat value, yielding the low heat value.

The difference is significant. As mentioned previously, there are two sources of water vapor in the exhaust of a fire, and low heat values take both into account. Wood contains water (its moisture content), and water vapor is also manufactured in the combustion process. When burned completely, each pound of ovendry wood produces about 0.54 pound of water vapor. For wood with a moisture content of 25 percent there is another quarter pound of water vapor going up the chimney for each piece burned whose ovendry weight would be 1 pound. The total amount of water vapor is 0.79 pound, which represents about 830 Btu of potential energy. The assumption behind the concept of low heat value is that this energy is not usable. The low heat value of wood with a 25 percent moisture content is thus about 830 Btu less than its high heat value, or about 7770 Btu per piece whose ovendry weight would be 1 pound, a decrease of about 9 percent.

The water vapor in the flue gas, along with everything else, also carries away sensible heat. As long as the gases leave the house at any temperature above room temperature, some of the heat generated in the fire was not recovered as useful heat in the house. Some authors have incorporated an estimate of this loss in their lists of available energy of different woods by making quite arbitrary assumptions about flue-gas temperatures and the amount of combustion air. This is not appropriate. The amount of heat going up a chimney is not a property of the wood burned, but of the heat-transfer properties of the stove and chimney, and thus belongs rather in a discussion of the energy efficiencies of stoves (Chapter 6), not in a list of wood types.

When assessing the energy content of a cord of firewood, the most important parameter is the ovendry density of that kind of wood, since a pound of dry wood of any kind has nearly the same energy. The densest woods have the most energy per cord (at equal moisture content). Moisture in wood decreases its useful energy. If all types of wood had the same cost per cord, the better buy would be the denser woods. If wood were sold by the ton, as is sometimes the case, the best buy in terms of energy would be the driest wood. No fuelwood dealer I am aware of sells wood by its energy content. Reasonably accurate BTU assessments would require both weighing and a determination of moisture content.
Click to expand...
 
ANeat said:
Here is an interesting article discussing the actual btu content, they eventuelly come up with a 6050 btu per pound value for wood with 20% moisture.
Click to expand...

Adam, that is a very good explanation of what is really happening when wood burns in a stove. One huge quibble I have is that they are saying that unseasoned wood only produces half the heat of seasoned wood. This is only true when comparing weights, not volumes.

A freshly cut tree has even higher moisture content, often above 60%. Similar calculations show that this fresh wood has only 2000 Btu/pound of energy available. This explains why it is so difficult to burn freshly cut trees.
Click to expand...

They are speaking of weight. We figure wood (and fill our stoves) by volume. Disregarding physical shrinkage, a cord of green wood contains the same amount of burnable material as a cord of seasoned wood. Some woods like ash and locust shrink very little when stacked, so the only real difference between them would be the unrecoverable heat used to evaporate the extra water. That's not as much as most folks have been led to believe, but it is heat lost nonetheless.
 
Aheat, I wasn't sure my figures for mc taking away btus were right either. I don't know how to calculate it any better though... Maybe one of those engineer folks can chime in.

Matt
 
EatenByLimestone said:
Aheat, I wasn't sure my figures for mc taking away btus were right either. I don't know how to calculate it any better though... Maybe one of those engineer folks can chime in.
Click to expand...

No engineer here, but the biggest problem lies in the way moisture contents are determined and expressed. It is the total weight of the water divided by the the ovendry weight (at 0% MC). So a 1.25 pound piece of wood at 25% MC as is commonly expressed has .25 pounds of water, which actually is only 20% water by weight, not 25%. A 1.5 pound piece of wood at 50% MC has .5 pounds of water, but that is only 33% water by weight, not 50%. And so on.

Then you have to account for the heat losses in both water evaporated and in unrecoverable heat from the water vapor formed by combustion. We need someone to write a program that covers all of these variables. It won't be me, the only programming I know about is on network TV. Maybe it can be done in a spreadsheet? Dunno. Don't wanna try, neither.
 
assuming the wood placed in the stove is @ 50*f then
water from 50* to 212*f requires 162 btu/lb of water
water turning to steam requires 970 btru/lb of water
total= 1132 btu/ lb of water
2000 lb firebrix @ 10% mc would lose 200 lb water & require 226400 btu for mc heatloss.
2000 lb wood @ 25% mc would lose 500 lb water & require 566000 btu for mc heatloss
cord of wood weighs more than 2000 lbs depending on species & mc
 
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