Wood Stove vs. Coal Boiler efficiency

 
User avatar
McGiever
Member
Posts: 10130
Joined: Sun. May. 02, 2010 11:26 pm
Location: Junction of PA-OH-WV
Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
Hand Fed Coal Boiler: BUCKET A DAY water heater
Hand Fed Coal Stove: Warm Morning 414A
Coal Size/Type: PEA,NUT,STOVE /ANTHRACITE
Other Heating: Ground Source Heat Pump and some Solar

Post by McGiever » Wed. Jan. 10, 2018 10:18 pm

lsayre wrote:
Wed. Jan. 10, 2018 4:52 pm
It all depends upon the weight. I pay $165 per ton (before tax, my pick-up). Mine come in a 6 pack, with each block weighing 3.5 lbs. That's 21 lbs. of wood in each pack. 96 x 6-packs per pallet. 1 ton per pallet. Or about $1.72 per pack.
Assuming they are the same weight, 12 of your's on pallet is $3.44 compared to the 12 @ $4.99 I seen.

 
User avatar
Rob R.
Site Moderator
Posts: 17979
Joined: Fri. Dec. 28, 2007 4:26 pm
Location: Chazy, NY
Stoker Coal Boiler: EFM 520
Hand Fed Coal Stove: Chubby Jr

Post by Rob R. » Thu. Jan. 11, 2018 1:19 pm

lsayre wrote:
Wed. Jan. 10, 2018 5:36 pm
I 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.
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?

Seems like your pea coal is the easiest to manage.

 
User avatar
lsayre
Member
Posts: 21781
Joined: Wed. Nov. 23, 2005 9:17 pm
Location: Ohio
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Lehigh Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75

Post by lsayre » Thu. Jan. 11, 2018 1:22 pm

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.

 
User avatar
BigBarney
Member
Posts: 1853
Joined: Wed. Feb. 08, 2006 2:48 pm

Post by BigBarney » Thu. Jan. 11, 2018 2:19 pm

The natural sugar (Carbohydrates) In the wood hold them together just like wood

pellets , pressed with high heat and it happens.

BigBarney


 
User avatar
lsayre
Member
Posts: 21781
Joined: Wed. Nov. 23, 2005 9:17 pm
Location: Ohio
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Lehigh Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75

Post by lsayre » Thu. Jan. 11, 2018 2:33 pm

BigBarney wrote:
Thu. Jan. 11, 2018 2:19 pm
The natural sugar (Carbohydrates) In the wood hold them together just like wood

pellets , pressed with high heat and it happens.

BigBarney
Makes sense! Thanks!!!

 
User avatar
lsayre
Member
Posts: 21781
Joined: Wed. Nov. 23, 2005 9:17 pm
Location: Ohio
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Lehigh Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75

Post by lsayre » Mon. Jan. 15, 2018 9:15 am

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.

 
User avatar
lsayre
Member
Posts: 21781
Joined: Wed. Nov. 23, 2005 9:17 pm
Location: Ohio
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Lehigh Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75

Post by lsayre » Tue. Jan. 16, 2018 7:46 am

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.

 
User avatar
lsayre
Member
Posts: 21781
Joined: Wed. Nov. 23, 2005 9:17 pm
Location: Ohio
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Lehigh Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75

Post by lsayre » Sat. Jan. 20, 2018 9:01 am

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.


 
User avatar
Rob R.
Site Moderator
Posts: 17979
Joined: Fri. Dec. 28, 2007 4:26 pm
Location: Chazy, NY
Stoker Coal Boiler: EFM 520
Hand Fed Coal Stove: Chubby Jr

Post by Rob R. » Sat. Jan. 20, 2018 9:54 am

lsayre wrote:
Sat. Jan. 20, 2018 9:01 am
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.
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.

 
User avatar
lsayre
Member
Posts: 21781
Joined: Wed. Nov. 23, 2005 9:17 pm
Location: Ohio
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Lehigh Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75

Post by lsayre » Sat. Jan. 20, 2018 10:30 am

Rob R. wrote:
Sat. Jan. 20, 2018 9:54 am
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.
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.

 
User avatar
McGiever
Member
Posts: 10130
Joined: Sun. May. 02, 2010 11:26 pm
Location: Junction of PA-OH-WV
Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
Hand Fed Coal Boiler: BUCKET A DAY water heater
Hand Fed Coal Stove: Warm Morning 414A
Coal Size/Type: PEA,NUT,STOVE /ANTHRACITE
Other Heating: Ground Source Heat Pump and some Solar

Post by McGiever » Sat. Jan. 20, 2018 11:19 am

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?

 
User avatar
lsayre
Member
Posts: 21781
Joined: Wed. Nov. 23, 2005 9:17 pm
Location: Ohio
Stoker Coal Boiler: AHS S130 Coal Gun
Coal Size/Type: Lehigh Anthracite Pea
Other Heating: Resistance Boiler (13.5 KW), ComfortMax 75

Post by lsayre » Sat. Jan. 20, 2018 11:57 am

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?

 
User avatar
McGiever
Member
Posts: 10130
Joined: Sun. May. 02, 2010 11:26 pm
Location: Junction of PA-OH-WV
Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
Hand Fed Coal Boiler: BUCKET A DAY water heater
Hand Fed Coal Stove: Warm Morning 414A
Coal Size/Type: PEA,NUT,STOVE /ANTHRACITE
Other Heating: Ground Source Heat Pump and some Solar

Post by McGiever » Sat. Jan. 20, 2018 6:34 pm

lsayre wrote:
Sat. Jan. 20, 2018 11:57 am
Are you sure that cutting them in half would extend their burning time, and/or make them burn at more even temperatures?

:roll: 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?
It would exactly, but if it would burn more and/or faster you just change your methods accordingly. :)

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.
McGiever wrote:
Sat. Jan. 20, 2018 11:19 am
Larry, What if you sawed some blocks in half for more even temp output over the course of entire burn?
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. ;)

Post Reply

Return to “Coal News & General Coal Discussions”