Assuming they are the same weight, 12 of your's on pallet is $3.44 compared to the 12 @ $4.99 I seen.
Wood Stove vs. Coal Boiler efficiency
- McGiever
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- Rob R.
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In my area a delivered face cord of seasoned firewood is $75, so $225 per cord. The sawdust blocks win on storage density, but I wonder if they will start to crumble over time or absorb moisture?lsayre wrote: ↑Wed. Jan. 10, 2018 5:36 pmI haven't priced firewood in many years. I have calculated that 1.4 tons of the compressed sawdust blocks should be the honest BTU equivalent of a typical full cord of well seasoned, cut and split, mixed hardwoods though.
$165 x 1.4 = $231
So my benchmark to beat is $230 for a "full" cord of well seasoned mixed hardwoods, cut and split. If it costs more than $230 for firewood I'm better off getting the sawdust blocks.
Seems like your pea coal is the easiest to manage.
- lsayre
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My sawdust blocks have been in the garage for about 2.5 years, and they seem good as new. Taking up 2 typical pallet spaces. It's amazing how well 24K PSI of compression can hold them together. No fillers or glues are used.
- lsayre
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Originally I was hoping that when I dropped down to burning 3 compressed sawdust blocks at a time instead of 4 I would get 5 hours of burn time, but with 3 blocks per feeding I'm only getting 4-1/2 hours of burn time.
Previous: 4 blocks per load, with feeding every ~5.5 hours = 19,920 input BTUH
Current: 3 blocks per load, with feeding every ~4.5 hours = 18,260 input BTUH
The small difference in heat input/output has not noticeably lowered my living-room temperature by much. The bigger difference is in feeding the stove more often.
Previous: 4 blocks per load, with feeding every ~5.5 hours = 19,920 input BTUH
Current: 3 blocks per load, with feeding every ~4.5 hours = 18,260 input BTUH
The small difference in heat input/output has not noticeably lowered my living-room temperature by much. The bigger difference is in feeding the stove more often.
- lsayre
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For what it's worth, with my particular stove, if I reload it with the compressed sawdust blocks whenever the hottest spot measured on the stove (at top center, on lower shelf just forward of the exhaust pipe flange) reads 250 degrees F. (as measured by a laser thermometer) I can add more blocks and reasonably confidently expect them to ignite without difficulty. At 240 degrees self ignition becomes well more iffy, and by 235 degrees it is more seriously iffy. For these latter two cases, I find that I often have to toss in some wood pellets or kindling, and even some newspaper in order to get the blocks to ignite. This method proves to be more reliable than applying fixed time intervals between loadings.
- lsayre
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I finally got around to compiling and analyzing the data from a second full week of wood burning in conjunction with the coal boiler running, and exactly as for the first set of data, it requires the burning of 1.8 BTU's of wood to displace 1.0 BTU's of coal. So since they both cost me the same amount on a BTU to BTU basis, I must conclude that my home heating bill would go up by about 80% if I was to heat my home exclusively with wood, and heat it to the same comfort level across all four of its independently heated zones.
- Rob R.
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I think what you mean is that heating your house with sawdust blocks burned in your Comfortmax stove would cost about 80% more than burning anthracite in the Coalgun. My question is how much of that 80% is due to the difference in the fuels, and how much is due to the differences in the appliance and distribution?
If you burned wood in the Comfortmax for a few weeks and then burned coal in the Comfortmax for a few weeks to compare, I think it would be a much better comparison of the two fuels.
- lsayre
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I agree fully. But my wife isn't ready for this experiment yet.
Since compressed sawdust blocks burn rather hot for the first 2 hours, and then slowly cool over the next ~2-3/4 hours (beyond which re-establishing a fire becomes progressively more difficult), the heat output is highly erratic and not very controllable via the stoves bimetallic air inlet.
I would hope that coal delivers a more steady and controllable heat output throughout its nominal 12 hour reloading cycle.
- McGiever
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Larry, What if you sawed some blocks in half for more even temp output over the course of entire burn?
That block size is for open fireplace burning, not size for in a tight stove like you have there.
Got a band saw there?
That block size is for open fireplace burning, not size for in a tight stove like you have there.
Got a band saw there?
- lsayre
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Are you sure that cutting them in half would extend their burning time, and/or make them burn at more even temperatures?
Wouldn't cutting them expose more surface area to the air and thereby cause more wood to burn, leading to more initial heat, and less even temperatures, as well as less overall burn time?
Wouldn't cutting them expose more surface area to the air and thereby cause more wood to burn, leading to more initial heat, and less even temperatures, as well as less overall burn time?
- McGiever
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It would exactly, but if it would burn more and/or faster you just change your methods accordingly.lsayre wrote: ↑Sat. Jan. 20, 2018 11:57 amAre you sure that cutting them in half would extend their burning time, and/or make them burn at more even temperatures?
I was not making any reference as to extending the burn time.
To not try is to never know. If you are content with it now, then try nothing.
Wouldn't cutting them expose more surface area to the air and thereby cause more wood to burn, leading to more initial heat, and less even temperatures, as well as less overall burn time?
How tightly are you grouping the full size wood blocks now...tight in one mass? I think not. If it were coal you were burning would you use 3 or 4 big blocks? I think not.
And when it is necessary to add more fuel again to maintain the continued fire would be a breeze so to keep an even fire and even heat output. H3ll, might even cut blocks into thirds.