Woodedacre;
I never had a coal boiler, we always used a coal fireplace. I can tell you, a boiler is different from a fireplace. In a fireplace you set the air vent so the fire is burning but not raging and not so little that it goes out.
Remember, with coal the limiting factor is air. More air, more fire. You can light 1 ton coal, if you adjust the airflow it will burn for a month. Very different from wood.
So, just imitate how you would burn coal in a fire place to a boiler.
In a fireplace you need a constant flow of air so the coal bed is burning but not raging but also not so little that the fire goes out.
In the boiler it's more difficult because of the on off cycle of the fan. So, you fan needs to come on frequent enough so the coal keeps burning but not so infrequent that it goes out. 1-2 hr off, and it might be out. Especially anthrocite. That's why it's a good idea to mix anthrocite with bit coal that keep lit longer than anthrocite.
Anyway, so you must keep the setting of the diff small to imitate a steady airflow. In my 250coal it's anywhere from 5-7. If its warm outside 5, if its a cold day more like 7. I keep it at 5. And it works great.
Now, coal is like a train, once it goes it goes with a momentum. Once a coal fire is lit it gives out tremendous energy. So when the fan shuts off, the train is going and the fire will keep heating the water which will over shoot in temperature. Mine goes 10F over the top settings. So I set my top at 170-172, and I get 180f top.
Now, like a train coal fire takes a lot to get it moving. Watch the fan kick in. Nothing happens for minutes. It take some time for the coal fire to gear up again. There fore your bottom number may fluctuate too.
Mine is set at 170/165/5diff. I get readings 160-185-190 even. I really don't care. If you have a coal fireplace do you keep measuring the surface temperature? Never ever. What do you measure? Is the room warm enough.
Do the same with then boiler.
Just try this trust me;
Set it 175/170/5 diff or anywhere 3-7.
Mix anthrocite with bit coal, or anthrocite and 2-3 logs.
Load/ fill up the entire firebox with coal up to the fire bricks front to back. 3-4 bags.
Lite it (I use pre soaked match lite charcoal for easy lighting).
Once lit, about 30 min; please don't mess with it. No looking, no poking, no nothing.
After 12 hrs very gently shake the ashes off for 15'sec. Gently, don't let the unburned coal fall down between the grates. The rule is shake till you see red ash fall down in the ash pan. Than stop when you see red ash in the ash pan. Difficult in a boiler to see. So shake gently for 10-15 second and stop. No steering, poking, raking, or nothing. If its very cold out, you would normally add 3-4 shovel of coals. Not at the first 12 hrs after lighting it. 3-4 bags of anthrocite will heat my 4500 sqft house and water tank for 26 hrs.
Just try it, mine is working awesome just doing it this very way.
If your's won't there has to be something wrong with the boiler or how you operate it, or the installation, or all.
Since you have been heating with wood no problem, I really think that you just have to get used to heating burning with coal. It's much much more difficult than wood at first.
Again, anthrocite is actually the most difficult coal to burn. So, if you can burn bit. coal, that would be about 100 times easier.
Bit coal burns like wood. Ohio bit coal smells like Satan just came over for supper but boy it burns. Most people burn ky bit coal, with great luck. It has less sulfur,and much cleaner. I love anthrocite because it's so clean. No, smell, so smoke. Awesome. However, very hard to light, and very hard to keep burning.
I mix it with bit coal. It help to keep the fire more steady. I put a football size bit coal in the firebox on sat at 3pm. It's 50%burnt at Sunday at 7pm. Wow.
If you change your diff to higher than 7 I will guarantee you, the fire will go out. Especially if its only, 35-40f outside; too warm.
Again remember, coal fire will over shoot the top number; so at 170/165/5. You get 180+/160/ actual differential is 20+ even though you set it at 5diff. So, the fan will not kick in until the temp drops from 180+ to 160!!!!!! In a 45 F day, that could be 2-3 hrs. The coal will go out for sure.
If you have settings 180/165/15 diff like you would with wood burning, with coal you will get;
195/155+/40!!!!!diff. Remember you said that last year those were your setting when you tried to burn anth coal, and the fire kept going out? Are you surprised now that the coal fire went out with an actual diff of 40 degrees? In a warmer day it will take hours and hours for 250 gallons of insulated water to drop 40 degrees for the fan to kick in!!! That is just not happening with coal. Not ever.
The diff has to be 3-7 no more. Just keep it at 5 for now.
Let me know how it went.
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Topic: NCB-250 COAL (Read 14455 times)