making coke and not heat

I'm having a problem with my Vogelzang Norseman 2500 wood / coal burning furnace. I bought this furnace online from the Vogelzang company about 1 year ago and just recently got my butt in gear and hooked it up about 3 months ago. They say only to burn bituminous (soft) coal which I am doing, but the coal is not burning completely and turning into what I believe is coke (lava rock type looking rock). No matter what I do this rock forms. I leave the draft / ash door open and it still forms. I also have the forced draft induction kit which hooks up to the thermostat and blows air into the firebox when more combustion is needed. The furnace doesn't put that much heat out either. The house will heat up to around 68 - 70 degree and when I wake up in the morning after around 8 hours the temp will be in the low 60's. I have around 5000 a square foot house consisting of 3 levels of 1750 square feet per floor, but I'm only heating the middle floor with this furnace. I had a chimney sweep come in and inspect the installation and chimney which they said that they would of not of done a better job of installing it. The chimney was 21' high and and about 1' over the peak of the roof and they suggested that I add another section which I did and the height is now 24' high and 4' over the peak of the roof and still not anybetter. I contacted Vogelzang and they said that nothing is wrong with the furnace because the design has been this way for many of years and nobody has complained or had any problems. Has anybody had / heard of any problems like this or know why this is happening? My gas furnace has stoped working completely and now this is the only way that I have to heat my home. I'm lucky that it's been a mild winter soo far. I'm getting very discouraged and frustrated. Can somebody please explain with is wrong and why this is happening?

Thank you

...Rich

Tigermanrich wrote:I'm having a problem with my Vogelzang Norseman 2500 wood / coal burning furnace. I bought this furnace online from the Vogelzang company about 1 year ago and just recently got my butt in gear and hooked it up about 3 months ago. They say only to burn bituminous (soft) coal which I am doing, but the coal is not burning completely and turning into what I believe is coke (lava rock type looking rock). ...Rich

If it is reddish and looks like lava, that is clinker, not coke. Coke burns, clinker doesn't. Clinker is fused, melted ash.

Where are you located and where is the coal from? A lot of bituminous has low ash fusion temperature, and will cause clinkers to form no matter what you do.

Chris

Thanks for the reply Chris!! The fire burns really hot at first, but eventually will die down and form these lava like rocks when it cools. When it burns.. the coal seems to be like wax and all melts and fuses together and I have to break it up or the whole firebox will be filled with this lava type of rock after it cools. These rocks form when it is burning also, but when broken up will burn up a little and will still fill the firebox when cool. I was told that clinkers are hard and shiny and not light and fluffy like what I am getting. I shake the grate as often as I can and usually do it about 5 - 10 times a day thinking that there is too much ash build up, but nothing seems to help. I'm located in Beaver County PA which is about 20 minutes North from the Pittsburgh Airport. I get my coal about 30 minutes North from where I live at Wampum PA (Kerry Coal yard).

Yup, you're getting clinkers. Bituminous clinker is just like lava rock, and the way you mention the coal fuses/swells together is a perfect description of a bituminous fire (and the challenges that go with one).

You may want to shake the fire less and only break up the coal as necessary. The more you mess with the fire, the more clinker you will have.

What size are you burning? Many times it works better to burn raw lump size in these furnaces. Almost burns like wood....

Chris

Hello Rich, welcome to the forum. Burning Bituminous coal can be very frustrating because of the wide variations of the quality and burning characteristics.

That lump of [coke] that is remaining you describe as 'lava rock' is it light and porous, and crumbles in your hands?? If so, it is just the remaining ash from a shallow bituminous coal fire.

Does a wood fire burn OK in the stove? Does it create enough heat to heat that one floor of your house? I think that furnace is pretty small for the square footage you are trying to heat. This depends on the insulation and windows in the house.

Since you are not that far away from Anthracite coal sources I'd try getting several bags of Nut size anthracite coal. Build a hot wood fire, let it burn down to a hot level bed of coals, Add about 1-2" of anthracite coal over the entire bed of coals. Close the loadiing door, and open the air control on the ashpan door. Let the 2" of anthracite to get nice and hot. You can then add progressive layers of anthracite up to the top of the firebrick of the firebox, even mound it up in the middle. You want a coal bed at least 6-8" deep, the deeper the better. I burn a 16-18" deep coal fire in my boiler.

You will control the heat by the ashpan air control. The air control in the loading door should stay closed.

I believe you will find that you can maintain an effective fire for 8-12 hours with anthracite. If you can load more anthracite on a still hot fire, let it get burning then shake the ash off the grates into the ashpan, Then topp up the coal in the firebox. This way you should be able to maintain an anthracite coal fire for weeks at at time. Anthracite burns down to a fine ash, either powder or fine crumbly pieces, they don't stick together.

If you follow the above proceedure with Bituminous, you will probably have much more ash, and some fused, melted-together ash remaining on the grates when the fire goes out. This melted, fused ash is as Chris said above called Clinker. It can fuse together in sheets that block the airflow through the grates and starve the fire for oxygen. With Bituminous coal I have to clean my firebox every few weeks

Greg L

Rich: check your PM's... Greg

.

Rich, take a look at this thread:

http://nepacrossroads.com/viewtopic.php?t=1278

Is that what you are getting?


Greg L

if it is not a clinker, but rather coke which sounds likely, you have a very interesting situation. i am not very familier with the type of furnace you have, however it sounds like there is way too much overfire/secondary air, and not enough primary/underfire air to burn the high carbon coke once the volitiles have flared. it is also likely there are potentially two other factors at work; make the coal bed as deep as possible, the coke needs to have heat reflected from each of the burning pieces in order to continue combustion and it needs more mass. also you may have coal with a high swelling index and is inherently more incli9ned to produce coke. next time if you can try valier coal yard in punxy. they have good nut bituminous. it is not likely you are getting clinkers from most pennsylvania coals.

Thank you all very much for the quick responses!!!! The coal I am burning is Egg coal which actually veries in size from about 2 to 6 inches. It seems like the load that I have has a lot of fine broken up coal. There are some pieces from 2 - 6 inches mixed in it but after filling up my wheel barrel I only get a small portion of good sized coal and the rest is like sandy and gritty. I've been throwing mixed shovle fulls in and not separating the sandy gritty coal from the big pieces. The things that you relate to clinkers are not really reddish in color, but are black and very course and light. It seems like the coal that I have also burns down and leaves some reddish to orange rocks that I assume are inside of the coal. I will have to take pictures and post them on here to give you an example of what I am referring to. Yes a wood fire burns fine also. The wood turns to ash like it is suppose to. The stove does heat the house fiarly nice at first and after a couple of hours of burning coal starts to cool down.

....Rich

Turn off the forced draft, which I have pretty much the same furnace. Also close the damper on the forced draft fan, this lets in alot of extra air in the firebox you don't need. This should help alot. Check you setting on your limit control on the back of the furnace, Mine is set at 140 on and 85 off. This setting extracts the most heat for me. Also fill the firebox full, the deeper the better. You wont get good heat with a few inches of coal in one of these.

Are these clinkers?

The previous pics did not show up....Here they are again:

Are these clinkers???

Definitely clinkers.
Are those dark ones a lot harder than the light ones, they look HARD.

Coaldsweat,
Not sure. I believe that thay are all about the same weight and consistancy though. I didn't try to break them up at all. I think that the reddish ones are mixed with clay though.

I mean is it really hard, like to break apart as opposed to breaking fairly easy.

is there anyway to stop these or is it just something that we have to deal with as part of life with burning the soft coal?