Freddy wrote:Bituminous I don't know. Certainly it has the potential to make an awful mess. Most of us here burn anthracite. That's "hard coal". It's much cleaner than bituminous and it's why most residential coal heat is anthracite. With just a tiny bit of care anthracite can be very clean. The most you should get is to notice a bit of gray ash dust on the windowsills when you do your Spring cleaning. It's much easier to clean a bit of dust than it is to watch your checking account get cleaned out by the oil man.
I burned 3300 pounds of bituminous for the "test drive" of my new installation this winter and am very pleased at how little mess there was, and 95% of what mess I had would be eliminated by having a boiler optimized for bituminous and some design changes to the boiler base. Cleaning the fire created a fair amount of dust as loose ash and chunks of coke and clinker would fall out of the cleanout door into my ash bucket while bringing out other pieces of clinker. Design problem, not a bituminous problem.
Bituminous does require regular brushing of the boiler heating surfaces - no less than once a month and weekly isn't too often, so a boiler with a big front door along with heat exchanger tubes that can be brushed out while standing would be preferable. With proper design, it's a 15 minute job tops. All I do is shovel out the collected fly ash/soot from the boiler base into a bag and dispose of it - very little mess. It's a little dirtier than anthracite due to the soot content, but not NEARLY as bad as the pure 100% black permanently-attached-for-the-rest-of-your-life soot I remember from burning bituminous in a hand fed stove.
I had about 3/16"~1/4" of buildup in my flue when I took it down for cleaning - a little more than I expected. I'll have to see how next season goes when it will be running full time. The fly ash is very light and fluffy, almost like little flakes, and might build up to a point and then fall off/blow out on it's own. I thought about drilling a small hole at the bottom of the elbow coming out of the boiler, waiting for a windy winter day and hitting it with the air compressor blow gun.
With my luck I'd just blow a huge cloud of soot out of the boiler and into the shop.
I would definitely install a similar setup inside the house with only one condition - easy access to the coal. I ran my Keystoker for 4 years downstairs and while it did a wonderful job keeping the finished basement warm and toasty using a bag every two days, carrying dripping bags of coal through the house and downstairs was a pain. So either a walkout basement with the coal bin right there or a sealed bin inside would be important. Keep a garden sprayer filled with water handy to keep the dust down during handling. My coal was fresh out of the wash plant and pretty wet when I picked it up, but towards the end it dried out and got a bit dusty. Really no different than anthracite, I suppose.
As for wood.....only if it's free. I do love a good wood fire - oak, hickory, beech, maple, etc. - when burning properly. Choked down in the airtights of the 70's/80's or those outdoor wood boilers, wood makes a stench worse than 10 coal fires. And then you have the bark and bugs all over the place. Best thing about wood is the ashes - good for the garden and there isn't nearly as much of it as with coal. But try shoveling out a month's worth of ashes out of an old Fisher "Papa Bear" stove - you'll fill two 5 gallon buckets and fill the house up with dust doing it....