15lbs of ash is good for how much wood you've burned! I'm wondering if others that run their boilers at lower firing rates experience the same accumulation or more? I'm sure those BioWINS are most efficient at high fire like your units get to experience, plus higher fan rates for pushing fly ash out better vs settling.
I just cleaned mine yesterday after only a ton and was amazed. The ash bin was 3/4 - 7/8 full and probably weighed 15-20lbs, the burn pot did not need any scrapping as the self cleaning soot blower works well. The "tubes" had about 1/32-1/16" of perpetual ash on them that the moving turbulators can not scrape off (similar action to the BioWIN's). It's light/fluffy and wipes off with a broom if wanted, no scrapping needed. The whole unit was disassembled, cleaned, and back online in 10 minutes. I'd say there was about 1 cup of ash was knocked out of the unit that was not in the ash pan.
I think this is generalizing a little too much. Assumptions are that pellets are available at a particular cost, as in your example at about $200/ton, and cord wood c/s/d at $250/ton. Where I live there are no nearby pellet plants, transportation costs are significant, and cord wood c/s/d and 1 year seasoned before delivery is about $185/cord. At these prices pellets at assumed equalized moisture content when burned of 8% have about 7800 btu/lb and wood at 20% moisture content has 6050 btu/lb. If available, pellets at $200/ton = $0.10/lb, and red oak at $185/cord = $0.05/lb. On a btu basis, red oak provides the same btu's at a cost of $0.065/lb as pellets, which results in pellets costing about 50% more than cord wood for the same btu's. In both cases labor costs would have to be included in fuel handling, which would affect the result.
But I think other costs also need to be included. For example, it takes a lot of energy with resulting CO2 to process and deliver pellets vs cord wood; it also takes time and land space to season cord wood, but the energy is provided cost-free by the sun and wind and CO2 is near 0. Handling costs would depend on local wage rates.
And then for someone like me, my physical exercise comes from working outside, which includes the tree felling, cutting, splitting, stacking, etc. I am healthier and I have no fitness club cost, for example. These benefits are substantial and if possible to measure in $$$, the equation tips much more strongly in favor of cord wood.
My only point is that each situation is different, additional costs need to be included, and a generalization doesn't fit very well.
You're right, additional costs are variable but I did not think my quote was too outlandish or too general. I stated it's hard to justify a new wood boiler vs a new pellet boiler unless you have your own wood yard nearby. That's my opinion and I stand by it as I did extensive research and cost analysis on my own project. If I want to get the efficiency I would get from a pellet boiler I would need a gassifier that costs at least $2000 more than my boiler did, plus I need to source a 1000 gallon tank to run it proper, insulate it, and have a place to put it all. The biggest thing I would need would be ample amounts of time for playing with wood, timing my fires to charge my tanks, and convincing my wife that this was all easier.
I burned wood for years cutting my own wood and really did enjoy it. However, at the time I was still sailing and had 6 month of vacation a year to blow. Driving to cut wood at my camp 20 miles each way (at 20mpg x $4.00/gal of diesel) to get 3/4 to a cord of wood in my truck. Maybe 1/2 gallon of gas/oil in the saw another $2. Another gallon of diesel in the tractor to run the splitter for $4, 1.5 hours of seat time in the truck, 2 hours cutting, splitting, and throwing in the truck, another 2 hours unloading, splitting, stacking in the crib with a beer. That's pretty much a day shot to get 3/4-a cord of wood and 10,000 blackfly bites in the Maine woods. Now, aside from my jestful sarcasm I really did like it and love being outdoors and heating my home with something I gathered with my own two hands (and truck, tractor, saw, splitter... all were not free either). The wood took up a large chunk of my dooryard as well as my downstairs garage where I would stage 2 cords. It brought in an unbelievable amount of dirt into the house along with an insane amount of bugs and SPIDERS (I HATE spiders)!
Since coming ashore, I learned quickly I have to work 50-65 hrs a week to make anywhere near the same income as sailing. Plus when I'm not in the plant, the pager/phone can go off at any minute and back to the plant I go. Purchasing wood the last 2 years, since I have no time to harvest my own, has been robbery! Do I think I should pay $185/cord of wood like you luckily can? Yes
$250 is a rip for "Seasoned" wood that was most likely dried in a damn swamp. My seasoned wood was most likely cut in January and split onto the truck before they delivered it judging how I couldn't find one check line in any stick. So the 22.5MMbtu of usable heat in a cord of Red Oak just got cut to 16-18MMBTU of usable heat. Or, i can get 16.5MMbtu/ton of usable heat from my pellets that I paid $177/ton for (
Useable heat from Maine Wood Pellets and Maine Wood Fuels is averaged at 8250 btu/lb over the past 8 analysis from the samples I send to the lab every quarter). To boot, I can stack 4 tons of pellets in my 2 cord crib downstairs with NO SPIDERS!
Generally, I save a TON of time and space while paying less per recieved btu's of heat. The additional energy/CO2 used to produce the pellets is marginable since they use sawdust waste to run the kilns at MWP. I found an article that showed about 3-4% of the pellets energy is used to make/transport it... from Canada to Sweden!
Even if I pay more/btu out of pocket, my time saved to do such while still burning a (nearly) carbon neutral product and supporting local business's vs foreign oil/gas companies is very worth it... Just like the farmer that put in the x2 BioWINS this thread is originally about. And as I stated, I would have bought the gassifier I set out to initially purchase if I had my own wood lot and been oblivious to how easy cheap wood heat CAN be.