Keystoker Koker question

My neighbor who has a koker has the following question:

I am having problem with my koker burning backwards and catching the hopper on fire and melting the nylon cam shaft.

What is the biggest cause of this???

It mostly happens when the stove is idling.

i was burning buck but switched to rice,

Will this fix it.

I just started my fire and it appears the fire is burning toward the hopper with the rice.

when i touch the bottom of the hopper it is warm.

Am i paranoid? Do i have a problem?

You do have a problem & hopefully someone with some more knowledge will jump in, was the top of your grate sealed so that combustion air isn't just going thru some cracks instead of the holes in the grates & were those holes all open & cleaned underneath before start-up? I've only been burning a few years & never encountered that problem, with cooler temps it could be the feed rate is too slow. You might try the search box to see if it's been discussed before.

Haven't seen a similar thread about this stove.

Everything has been sealed...

If your grates are properly sealed, the next big question is how is your draft measurement. If it is too high, the draft will pull air through the hopper and the fire will follow the new source of air flow. Koker's draft should be .02 - .03, .025 being ideal. Take a look at Keystoker's web site, they have new versions of their stove's manuals and they are easier to understand. If you don't have a monometer, make it priority 1 and get one. This may eliminate your problem, and will also save you on fuel costs as high drafts just suck the heat right out of your stove rather than having the heat waiting to transfer into your house.

Oh, Keystoker also suggests keeping your coal hopper full, again making it hard for air to filter through the coal.

Just ordered a manometer, thanks!!

My advice is your neighbor should only burn rice coal in the Koker. If everything is sealed properly he should be okay now that he's switched to rice. The larger sized buck could allow the draft to be pulled through the coal in the hopper, especially when it's low, and the fire will follow it up.
-Len