When this happens an examination of the unit may show no unburned corn in the firepot, corn still available in the supply hopper and no auger jams or other mechanical faults with the unit. This seemingly no-fault condition will be reinforced when after finding no problems, the owner restarts the unit and it performs normally (at least for a while).
Why did the stove go into shutdown mode for no discernible reason?

There are several possible answers to this problem depending on how your particular unit was designed and what type of controls were used.

1. All stoves and furnaces we are familiar with use some type of printed circuit board to control electrical functions. Some of these electronic controllers are very sensitive to line voltage fluctuations and may put the unit in shutdown mode after a momentary interruption of the electrical supply. (As when your lights flicker off and on during high winds.) The stove may still be running the exhaust blower but not the corn supply auger when you check it. This is because after a short power outage, the stove will still be hot and when power is restored, the flue gas temperature detector completes the circuit and re-energizes the exhaust blower motor until the flue cools down.
   No new corn feeds in at this time because of the control panel built in safety preventing an automatic re-start of the corn auger motor circuit after a momentary (or longer) shutdown.
2. If your unit has an air filter it may be clogged (dirty) to the point of restricting airflow through the plenum. This may have caused the high-limit switch in the plenum or the high-limit in the exhaust to activate (open) interrupting electrical power to the supply circuit. After a sufficient cool-down time, the switch closes, but the unit must be manually restarted and will probably repeat the same cycle again when the temperature again reaches max safe level. Change the air filter!  
   
3. Intermittent failure of the printed circuit board or one of the temperature limit switches due to poor electrical connections.
   Unless you are trained/skilled in electrical repairs this is best left to your repair technician.
   Check your owners manual - your unit may still be under warrantee.

Cleaning the pipe and stove results in improved fire and heat output, but the problem then reappears as before.

What is causing this frequent and very frustrating condition?

This is an easy one - the cause is almost certainly poor quality corn fuel. High moisture corn (Over 13%) will cause this condition in most units.  We are speaking here from first hand experience. The first year we heated with our corn furnace we used our own bin-stored corn with a moisture level of 15%. (This is about average moisture for farm stored corn and is all that is required by most mills.) We had to shut down and clean the flue and furnace every five weeks. Now that we use our cleaned/dried corn fuel we clean our flue pipe once in the entire heating season using the same furnace!

This is why WE KNOW NOT ALL CORN USED FOR FUEL IS THE SAME!!!

This is a common result of some type of trash in the corn that has resulted in a full jam (stoppage) of the auger supplying corn to the firepot. This unfortunately sometimes also results in damage to the auger drive motor and/or the auger. At the very least this condition will result in necessarily having to empty all corn from the supply hopper to get at the obstruction, which may be right at the mouth of the auger or much worse might be jammed part way through the auger tube where it is not visible. When this happened we sometimes had to open up our unit to get at the auger drive motor (after disconnecting the unit from the power) and manually turn the motor and auger backwards to clear the obstruction. This can be a very troublesome, difficult, and time-consuming problem that can be easily be avoided by using clean corn fuel.

SPARKS FARMS has not experienced this problem since we began cleaning all corn fuel in our commercial mulit-stage grain cleaner.

This a problem we experienced occasionally years ago before we purchased our multi-stage commercial grain cleaner. The stove/furnace will be operating normally until a broken corncob piece, spear from the corn stalk, or other trash enters the fuel supply auger tube. The obstruction isn't quite large enough to completely jam the auger, but it does create enough drag to slow the very small auger drive motor down to a crawl. In the meantime the fire goes out due to lack of sufficient fuel delivery to maintain the fire. Eventually the trash exits into the now non-burning firepot, and the auger continues to add more unburned corn until the flame out detection switch (or flue gas temperature switch) shuts down the stove. Result - a cold house, a frustrated owner and one more example of why all corn fuel is not the same.

This is a complaint we have heard a few times from stove owners over the years. The cause is almost always leaking exhaust gases from faulty joint seals in the pellet pipe connections between the back of the unit and before the pipe exits through the building wall to the outside. All stoves we have seen incorporate a forced draft exhaust design, meaning a blower internally positioned in the unit blows the gasses out through the flu pipe. This action creates a low-grade pressure inside the pipe that will in turn force gasses and fly ash (Soot) through any existing breaks or gaps in what is supposed to be airtight pipe joints.

The problem is typically easily remedied by dissemble and inspection of the pipe sections. (When the unit is not operating) Change any sections showing corrosion damage, and seal all pipe joints with high temperature silicon sealant as they are reassembled. Stove manufactures make specific recommendations on sealing material to use with their units. Refer to your owner's manual and follow manufactures recommendations.

A few units use positive air pressure inside the fire chamber. This may allow gasses and soot to enter the home through a faulty door gasket or improperly adjusted door latch. Most stoves have the exhaust fan unit positioned down streamed from the firepot so air drawn into it, thereby preventing the problem just detailed.

If these possibilities have been eliminated and the problem still persists a qualified repair technician familiar with your stove model should be consulted, as a more serious internal problem such as a crack or broken weld may be present.

Incidentally, if the complaint involves the flu gas odor in the home, including the odor of burning corn, look at these same possibilities as the probable cause. There should NEVER be any odor or gasses from burning corn inside the home from a properly installed and operating unit, no matter who the manufacture was.

SPARKS FARMS recommends any unit exhibiting such symptoms should not be used until the cause is identified and corrected.