Soot Reduction

I'm getting a lot more soot in the stack than I would like. I am burning in an Energy king boiler and it is designed for coal. I have the model with the draft induction fan but have not found it necessary to use it. There is a manual air control in the ash drawer. There is no air control for air over top of the fire. Quite a bit of volatiles in the coal I'm using so I have been leaving the door ajar for about the first 30 min after loading and this helps some. Flue is 8 inch double wall insulated stainless and has plenty of draft. I do not have a baro in it right know as I am also burning up some junk wood I have. Got a tee right off the boiler so putting one in is no problem. Feed door is cast iron but i could easily put an air control in it and I may do that. Any thoughts on how to cut down on the soot ?

I have found that you must be an extremely good fireman to keep high vol coal from making gobs of soot... last year I burned 25 ton of Pittsburgh Nut, that is very high vol. I had to clean my flue passages once a week. Fire smoked all day long, the hotter it was the more it smoked... try banking over left to right keeping the green coal from covering up the caked hot coal...

good luck

for soot reduction try banking it side/side or back front; install a secondary preheated air source; install firebrick or more insulative material above the fuelbed along the boiler walls to increase the efficiency of the flame; install a stoker. Is the chimney building up w/ too much soot or just the boiler? If it's just the boiler (provided it's designed properly) you should be able to brush down the passages quite easily once/week with not really any trouble at all. If it's the chimney, well, use a bigger chimney.

How high is the chimney?

Why are you not using the forced draft the extra air will burn the

coal much better and also supply some excess air in the firebox

to help burn up the volatiles.



BigBarney

My chimney is about 20ft ,only calls for a minimum of 12 so that should be alright. The biggest reason I don't use the forced draft is that it uses about twice as much fuel and doesn't heat the house any better. I expect the biggest reason for a lot of soot is just the soft coal. Brushing the chimney weekly may just be the way of it. The only hard coal around is trucked in and the last time I checked it was $309 a ton, for that price I may as well use propane. I'm happy with my boiler ,just wish I had a little less soot.

if chimney sooting, not boiler sooting is the main issue, the problem is the chimney being too small. the chimney you have currently may work fine w/ regular cleaning, but a larger chimney would enable the soot to break off and fall back down the chimney to the cleanout before the buildup impairs draft. there are things you can do to mitigate soot, as i've mentioned. If you don't want to clean the chimney very often the permanant solution to that is to use a larger diameter chimney.

Since my last post I have made a couple of modifications to my boiler. I drilled three two inch diameter holes in my loading door and made a simple swinging air adjustment, this gives plenty of over fire air to burn off volatiles. Also installed a barometric damper in my clean out tee. removed the chimney cap , because the holes were too small. Yes I will be building a new cap with bigger holes. So far this has greatly improved the problem and I have not had to brush the chimney since.

zipdog wrote:There is no air control for air over top of the fire. Quite a bit of volatiles in the coal I'm using so I have been leaving the door ajar for about the first 30 min after loading and this helps some.

I must have missed this thread before ....I have to do the same thing with my old circulator stove, there's no secondary (above coal bed) air control but it's not that big a deal because even though the loading door is barely ajar to burn volatiles better it is still latched so it can't come open on it's own. I use a Baro damper as well and it helps keep hot air in the firebox longer helping to burn off volatiles. Another thing I do is burn a roaring (but not overfiring) wood fire (baro capped) with good hard wood so there's no creosote and it blasts the soot out pretty good. I get flakes of soot all over on the snow afterward but they don't hurt anything. I only brush out the chimney once per season and it doesn't really even need it then.

zipdog wrote:I will be building a new cap with bigger holes.

Can you just modify the one you have? Does it have the spark arrestor screen or just holes?

In answer to the cap question, it's too short vertically to do much with. Has no screen just slots. I think I will take about a 12 inch piece of single wall and cut three large U shaped openings which will leave me with three tabs sticking up that I can pop rivet the dome off the old cap on, that way I can pop the whole thing off easily for maintenance. All I need is to keep the rain out.

Hey Zipdog, Did you purchase that boiler used up in Wisconsin recently?

No, my boiler is an energy king that I bought new last January when I got fed up with an OWB. Still trying to sell the stupid thing but that's another story. The chimney came from a fireplace my neighbor tore out. Real nice 8 inch double wall all stainless. when it's free ,hard to complain. I like the whole thing pretty well, this is my first year on mostly coal. I did buy a ton and half of some real crappy stuff last year but I don't count this as I did not burn it in my present boiler. I expected a learning curve. When you said you burned some wood real hot I decided to give that a try and I agree, it seems to remove some of the soot. Every thing I have done so far is working. As a side note this boiler likes big chunks, baseball or bigger is best. Tried some stoker coal because the mine didn't have any mine run the last trip over and it doesn't work worth a crap with my set up.