"Clinkers?"

I have a Hitzer model 503 insert, I am having a lot of trouble with what I call "clinkers", gray colored coal shaped, hard objects that will not pass through the grates. I shake the fire down two times per day, sometimes three. These "clinkers" force me to dump the fire usually two times per week and start fresh. I used to have a Keystoker furnace in my old house,ten years of use and not a problem, I am fairly new to handfired stoves, this is my third season with the Hitzer. Am I a victim of low quality coal?, besides inexperience.

Shaking it down 2-3 times daily is just my latest experiment to try and solve this problem. The things I am calling "clinkers"are not fused together, they are loose and are coal chunks (nut coal) that look as though they are burned out but still are solid enough that they will not break down to go through the grates. Usualy I shake it before feeding time, twice daily, just enough to knock the dust down until I see glowing coals dropping. I have tried raking the coals around in the firebox which seems to have little effect other than to over heat my gloves. Speaking of heat, I routinely run the surface temperature of the stove @ 600 to 750 according to one of those magnetic thermometers. I am thinking that the coal I am buying is poor quality, there are usually slivers of wood and the occasional rock included. I wouldn't expect to see that in quality coal.

Sounds like the Reading coal I bought several years ago.

Get some UAE coal if you can. or Blaschak, or I understand Jeddo is pretty good lately.

Greg L

I am a fellow 503 user. I too have dumped a couple of fires due to a clinker getting caught in the grate, and when trying to get the clinker out I have over rotated the grate. I believe, as previously stated, you may be shaking too much; and as a result unburned coal is getting lodged between the movable grate, and the stationary parts. A few thoughts:

- Shake only twice per day, 12 hour intervals seems to be good.
- Try not to move the grate too much, instead only agitate the grate with short choppy shakes, and several of them.
- Don't over shake, only shake until you begin to see small red chunks falling into the ash pan.

I am surprised on your stove top temperature. My magnetic thermometer is located to the right of the cast top for the hopper (on the sheet metal portion of the top), and the maximum temperature I experience is 400` F, and most times the temperature is about 250`F. My house is an 1800 sf, two story New England Cape, maintaining a house temperature of 70 - 75` F. I wonder if as a result of burning at such a high temperature you need to shake three times per day, and as a result there is not enough saturation time to burn the coal on the grate; where a lower temperature burning for a longer period of time would create a more complete burn.

Just my thoughts.....

I just moved my thermometer (I had it on the cast iron hopper lid) to the sheet metal as you suggested, it reads 360 right now. I have heard that Blaschack is a top quality product and my next batch will be from them. I even tried a few hundred pounds of buckwheat coal last year, but that practicaly ran through the grates before burning. Thank you all for your insight, my next move will be for a better quality coal. Thanks

I have had a similar problem with a Russo. Sometimes I've been able to work the "clinkers" through the grate with considerable effort. Other times, I've had to dump the fire as you have suggested. During spring clean out, the grates are lined with these things that block true ash from shaking through the grate, as well as blocking air flow through the coal bed.

I too burn nut, and the size of these things is far larger than standard nut. They are not clinkers, but very solid pieces of ash (stones).....they are not unburned pieces of coal. I'm sure my problem was with coal quality. Not only is the coal graded improperly, but dirty. This year I've changed to UAE coal and have not yet had a problem.

I pick up my own coal and, previously, had been getting it from STCP and American Premium . Although I have to go further for UAE coal, I feel it is worth the added travel to get it.....and is cheaper per ton ($165 vs $190 and $175 respectively)

CT coal burner wrote:I am a fellow 503 user. I too have dumped a couple of fires due to a clinker getting caught in the grate, and when trying to get the clinker out I have over rotated the grate. I believe, as previously stated, you may be shaking too much; and as a result unburned coal is getting lodged between the movable grate, and the stationary parts. A few thoughts:

- Shake only twice per day, 12 hour intervals seems to be good.
- Try not to move the grate too much, instead only agitate the grate with short choppy shakes, and several of them.
- Don't over shake, only shake until you begin to see small red chunks falling into the ash pan.

I am surprised on your stove top temperature. My magnetic thermometer is located to the right of the cast top for the hopper (on the sheet metal portion of the top), and the maximum temperature I experience is 400` F, and most times the temperature is about 250`F. My house is an 1800 sf, two story New England Cape, maintaining a house temperature of 70 - 75` F. I wonder if as a result of burning at such a high temperature you need to shake three times per day, and as a result there is not enough saturation time to burn the coal on the grate; where a lower temperature burning for a longer period of time would create a more complete burn.

Just my thoughts.....

This is intriguing, CT. I live in a 1500 sq ft two story farmhouse with new vinyl siding that has tyvex behind it, and also many new replacement windows. I'm lucky right now to keep the two main rooms of my house at maybe 70-71 degrees when it's about 25-30 degrees outside. I wish I had your temps, but then my stove is only rated at about 40,000 BTU's.
I've been experimenting with how often I should shake down since my stove is smaller than most. At present, I'm shaking down about every 4 or 5 hours. I have a thermostat on my stove that is usually set anywhere between 3.5 and 4.5 which is usually pushing the stove close to its max without overfiring. I wonder if setting my thermostat at the lower side even in the colder weather would still result in a more consistent burn for me, thus keeping the inside temps steady . In this weather, the thermometer creeps down to about 68 during certain points in the day.

Also, I've noticed an '"increase" in getting pieces of coal stuck in my grates. I probably shouldn't do it, but I get pretty aggressive sometimes when I'm shaking, in order to work those pieces loose. I have a scraper tool that helps, but I still have to shake pretty hard sometimes. I wonder if this increase in those pieces is due to burning at higher temps.

Just some thoughts.......

I just discovered my first clinker! Found it during a stove clean out. Luckily it didn't affect my fire.