If my reference to coking up doesn't make sense. .... what it's doing is burning into a solid clump and then won't push off the grate. It's hit and miss when it does it but usually in extreme cold when it's running longer.
Coal a little wet/damp? Friction on grate? The carpet on my Kaa-2 is more flat than your Ka-6. I don't have any problem. Dry wet/damp coal. Maybe sand grates. Any wax, or any other residue on grates from starting fire? Maybe try Buck size coal. I burn buck.
Your getting what I call clinker cakes. When your running your unit hard and burning a coal with a lower ash fusion rate, the ash will actually fuse together from the heat into a solid cake. This usually happens with coal that has a higher iron content or what is referred to as red ash coal. The fix is to mix in some buck or back off the air so it doesn't burn quite so hot. The long term fix is to blend in some white ash coal or coal that is lower in iron content.
This is not due to anything your doing and you don't have a problem with your Keystoker. It's the nature of the beast with higher iron content ash that is burned HOT in this cold weather. When the weather warms up a tad and it's not running so hard it will more than likely go away on its own.
I'm needing to get coal this weekend. I've been burning Mallard (Harmony) and I had tried Blaschak which I hated.....I drive from Central PA so I can go pretty much anywhere. Any suggestions? It never did this with the old Harmony coal.
I'm not sure how much to back the air down. My draft is having perfect. I'm picking up buck from a local guy. .... he sells Blaschak but I'll give it a try. Will I need to make any major feed our air adjustments with the change?
So I'm giving some buckwheat a try. Cleaned out all the rice and got it burning with buck and adjusted my air and damper to get my draft right after I had a normal coal bed and it's coking up again. When I cleaned the rice out I cleaned the whole boiler out do nothing is on the grates. What gives?
If your clinker cakes didn't go away with switching to the buck then you need to back off the air flow a bit and cool the fire down. I always had clinkers when I ran the UAE original. Your coal may just have a higher iron content. If you can get to the Keystone Anthracite site on Route 54 in Girardville Pa. Their coal has a lower iron content and I don't get clinker cakes anymore since I started using their coal.
What you got to lose right? Give it a try. Always remember, mileage may vary based on individual usage and performance.