bonnet limit switch on a koker

I am thinking about buying a coal trol but have a question on the bonnet limit switch on the koker.

Currently, the conv. fan limit switch controls the bonnet temperature maximum, so if the bonnet hits 200 degrees the fan limit switch shuts down the stoker and comb. blower so the furnace cools to a safer temperature. When installing the coal trol, if I just hook up the stoker and combustion blower to the module, and leave the convection fan controlled by the existing limit switch, will the bonnet limit switch still work the same or does the bonnet limit need to run through the CT in order to shut down the stove.

Also, my koker was built last year, does anyone know if the current convection fan they install on kokers are variable and compatible with the coal-trol's ability to adjust their rpm's.

Thanks for the help.

I have a Keystoker 90 chimney vent with a Coal-trol. The bonnet switch is between the feed motor and the Coal-trol, if the bonnet switch trips the system continues to run cooling the stove, by running the combustion fan, and the convection blower, but without anymore feed the unit basically runs out of coal, and burns out.

You can wire the high temp limit either to shut off the power to the Coal-trol entirely or just to shut down the stoker motor. You can also order the Coal-trol with an extra module on the side which will expose the interlock circuit and you can then tie the high temp limit switch into this interlock (this is actually how we ship units to Keystoker for installation at the factory).

As for the convection fan control through the bonnet limit switch, you can either leave that controlled through the limit switch or your can rewire the motor to be run by the Coal-trol.

Lots of options.

I think what I will do is just hook up the stoker motor and convection fan to the coal trol and leave the combustion fan wired to the koker's circuitry (this fan isn't controlled by the coal trol anyways, other than on and off). On my koker, the stoker motor is the last load on the circuit so that will be easy to switch over and the convection fan is also easy to remove from the circuit, it isn't in-line with the rest of the motors (upon delivery of the koker, you have to install the conv. fan and wire it to the existing circuit). This will leave the bonnet limit switch on-line as is and will control the combustion motor if the system hiccups. I may also run a line from the output of the bonnet limit to the coal trol so that the coal feed will get interrupted in an emergency (I would hate to lose unburnt coal to my ash pan even in an emergincy!! )

Thanks for all the help!!

I would recommend *not* doing that (leaving the combustion only on the high limit switch). It can cut off the combustion air but the fire can still be burning due to over drafting or some other unexpected air source. You really need to stop the fuel feed, and ideally the combustion air too, in the event of an over heat condition.

Either run the stoker output line from the coal-trol through the highlimit switch, run the power to the coal-trol through the high limit switch, or order it up with the interlock circuit hookup on the side and run that through the high limit switch.

Thanks for the safety tip. It was stuck in my head that no combustion fan = no fire, but you are correct, a good draft can still pull air through the coal bed. Will definitely hook the stoker up to be killed also, if need be. I ordered the coal trol this past weekend (w/out the interlock) so I will try to hook it up without the interlock first.