After working with the coal-trol the past few week, I have found the koker's convection blower works, as advertised, with the coal-trol, but as stated above it runs the blower within a smaller RPM range due to CFM needing to be set at 40 or above.
When I first tried the coal trol, my mind was still in digital (on/off) thermostat mode, so I couldn't wrap my head around how the conv. blower running pretty much all the time could keep enough heat moving as the stove's feed rate lowered after thermostat was satisfied. Keep in mind, this is my first year burning coal also, and it took a while just to get used to the burning characteristics of a solid fuel (long heat up and cool down times).
So, a couple weekends ago I re-hooked my conv. fan back to the coal-trol and forced myself to leave it alone all weekend. What I learned is that, at least during cold weather, the coal trol thermostat doesn't actually get satisfied, in a matter of speaking. In my situation with a CFM of 40 (MIN MAX at 6 and 65, CFT at 10), my stove's feed rate would drop to about 12-14 and hover there, thus keeping the plenum around 90 to 100 F and thus keeping the house's temp from dropping quite so fast (at the reduced blower RPM). When the coal-trol needs to ramp up the feed rate to maintain temp, it would rise up to about a FR 30. So the blower hardly ever shut off, which I believe is how the coal-trol is meant to run it. Similar to what I have read in the past, the coal-trol is best compared to cruise control on a car. You still burn gas (more than at idle) as you are coasting on a level stretch of road, but when you encounter an incline the car's rpm increase to keep you going that same speed. This is exactly what happens with your stove hooked up to a coal-trol.
I was also concerned with the fact that once the FR dropped below 9 or so, the conv. blower would turn off and all the heat generated as the FR fell to 0 wouldn't get blown into the living space (again, in my mind, I was comparing it to an on/off thermostat that drops the feed rate to idle at end of heating cycle). Obviously, in my case, if the feed rate drops and hovers to around 12 or so, the blower will keep pumping the heat upward.
I am pretty sure my coal usage is about the same or better, even with the lowest feed rate hovering around 12. This keeps the feed rate at a more constant value, where before when the blower was hooked to the limit switch, it (FR) would pretty much bounce back and forth between 0 and 30-40.
This coal burning deal is definitely a learning experience, but I am glad I took a few months to learn how to operate the stove manually before going the coal-trol route. I apologize if I steered anyone the wrong way with my starting post concerning the conv. blower. I still think the coal-trol really shines when you are using a smaller conv. blower on a stove that is operating in the living space, thus you are using the full range of RPM's on the blower, but it is working very well with the koker's equipment also.