A few days ago I was getting large amounts of smoke in the house when firing my boiler. It would be manageable as long as I didn't have the ash pan door open, but as soon as I would open that up, I would get tons of smoke at first from the firebox door. At this point I couldn't even fire it without filling the entire room with smoke. It soon got to the point where smoke would pour out of every tiny hole and seam in my flue pipe. There is a barometric damper installed on the flue pipe, and as you can imagine, it just puffed thick black smoke. At that point I smothered the fire and called a chimney sweep. He reported the chimney was pretty much clogged, and demonstrated after he cleaned it there was significant draw by holding a burning piece of paper in front of the firebox door and observing the smoke being drawn into the firebox. I should mention we also cleaned out the heat exchanger via both the access panel on the front, and by removing the flue pipe to get at the back. There was significant ash buildup in this area, we pulled an entire 5 gallon bucket out of there.
For two days after that I'm still having issues with smoke pouring back out of the firebox door as soon as I open it, and no matter how slowly I open it. If I keep the ash pan door completely closed, and my damper flap is mostly closed, I can still only get the door open maybe an inch before smoke starts pouring out. It didn't used to be this bad when I first started burning coal, but has just steadily gotten worse.
I'm not sure if the coal I'm burning is to blame or not. I started out with some bituminous coal my father in law had laying in his coal bin for years. This coal was a mixture of large lumps, maybe grapefruit sized, all the way down to an almost sandy consistency. It was very dark black and clean looking. This stuff burned great. It produced a small amount of grey smoke when I would first fire it, but other than that, I could stand there all day with the firebox door open. This next ton he got me came from 'his buddy who works at a mine' and it is supposedly Pittsburgh seam coal. It was still the cheapest of the cheap, he only charged us $37 a ton for it, and I'm starting to think I got what I paid for. This stuff is mostly 2-3 inch nuggets with a powdery coating over the surface of the lumps. They are a dustier almost grey color. It feels more solid than the first batch, almost like anthracite, but as soon as flames touch it, I get thick yellowish brownish smoke just roaring off of it and it stays that way for quite some time. It burns strangely too, after a few hours it starts to congeal like the other stuff, but it never really hardens, I don't know how else to describe it other than a gelatinous almost spongy mass. At this point it is producing thick black smoke, and if I poke it up and break the mass up, there is even more smoke.
A new symptom has also recently started with this stuff, my boiler has an oil gun on the back, and this smoke has taken to puffing out from the actual oil gun assembly itself, all the way back on the top of it where the breaker is to turn it on and off.
I keep my boiler temperature between 140 and 180, it is adjusted via a mechanical temperature gauge with a chain running down to a damper flap on the side of the ash pan. It used to run between 200 and 220 but I was having problems with the release valve blowing often, so I added some length to the chain which helped cool things down.
Can anyone please help me get this smoke situation sorted out?! It has gotten extremely frustrating and I'm just about ready to turn the dang oil gun back on. I would like to burn anthracite anyway as I understand it produces less smoke and ash and dust overall, but my father in law keeps showing up with this soft coal.
The only things I can think of are the coal is junk, or something is up with the barometric damper, as it is always 100% wide open. Maybe we jostled it around or something when we had the flue pipe off. I'm thinking that being wide open all the time has to be robbing draft that would otherwise help pull smoke up out of the firebox. Also another thing that changed was lowering the temperature of the boiler, and consequently the firebox to keep the release valve from blowing. Am I not burning hot enough to burn all the smoke off?
Any ideas and suggestions you guys have are very welcome at this point!