North Idaho Energy Logs in BlazeKing

The smoke issue is interesting. I haven't been able to find NEILs in Indiana, only the local "bio-brick", GrenHeat. I have experienced heavy smoke, but only for an hour or two from Cold and 15-20 minutes on coals. I've also not experienced the runaway you have.
I have loaded 80 pounds of the GrenHeat blocks numerous times, and it's always a RonCo affair, "Set it and forget it."
The smell outside is different though. Normally, on mixed hardwoods, I'll get a slight wood/charcoal odor. The GrenHeat blocks odor remind me of a blacksmith shop.

I one thing I have noticed is that the amount of smoke at start-up changes with how the bricks are loaded. if all the bricks are lined up, neat and orderly, then I tend to get heavier smoke than if they were loaded with a running bond pattern. I have also noted that the whole load burns, pretty much evenly if lined up, and front to back with running bond.
I know that Running bond would be impossible with NEILs, but how about E-W loading? Lighting the front log only. I wonder if the issues you are having are due to the large air gaps created when stacking round objects. The incoming stove air is then pushing the heat down the channels created, causing more and more fuel to be released (smoke). The same happens in the "log cabin" stack you tried first. Too much exposed surface area, creating too much free fuel that just overwhelms the capacity of the cat. Just an Idea...

Krogo.

Reading through this thread and thinking from a chemistry standpoint, I concur with trying a smaller load, stacked relatively tight, in case the issue is too little oxygen. The other option would be to open up your damper, but I assume you don't want more heat right now.

If your firebox is nice and hot, it might not look smoky if most of the off-gassing is remaining as vapor until it passes the cat.

Another possibility is water vapor (from combustion, not wet logs), may form a persistent plume if the humidity is high enough.

Before I leave for Alaska, I have used NIEL's for many years. My stove, once lit, stays lit, so we do not see the relighting at all. They are indeed hard to get started, so once I get a good coal bed of maple or locust, I toss two logs onto the hot coals, close the door and close the by pass.

Rarely is there any smoke. I just cleaned the stack this past weekend. I was pleased to get 4 measuring cups of build up out of the 17' of system that I run. Some of that was from the cap, as I swept from the inside of the house.

There is a balance of air to fuel and stacking a bunch of NIELS into a single load can create a very rich environment, with little to no moisture content (8%), out gassing is a possibility.

I will continue to use the product mostly because I am not home very often and my wife hates my ax!

Lastly, no one is more sensitive to the possibility of their chimney smoking than a guy that works for a stove company!!

We frequently burn 1-1.5-2 niels with a few small splits, and have a small white plume maybe 2-6 feet tall for over half of the burn. It does end with the shimmer. That is seen with the sun shining directly through the plume. The only time you can see visible smoke in the firebox is when it has direct sun, and then only a very tiny amount of smoke is visible sometimes. Even with a bright led flashlight, it generally appears crystal clear (my glass gets some amber coating, or lightest fog; the darker stuff is only the bottom corner triangles like over the B but usually not across the laze).

I burned these exclusively in my Kuma non-cat for the 14/15 winter.

Two and a half logs, configured as 5 halves stacked in a 3/2 pyramid, and closer to the front of the stove, was by far the most effective and efficient use.

Jason