- Condition: The dryer has detected the temperature of the air recycled from the cooling chamber is in excess of the setting of the thermostat monitoring the chamber.
- Alarm Action Taken: SHUT DOWN
- Component: Manual reset adjustable thermostat
- Location: The body of the thermostat originates in the junction box up inside the dryer inside of the square ductwork mounted just inside the lower access door under the burner. The sensor runs outside the junction box under the burner and mounts in the airstream under the burner with “P-clips”.
Tools Required for Service:
- Voltage/continuity meter
- Small standard blade screwdriver (to open cover and wiring terminals inside)
- 5/16” nut driver (if replacing thermostat)
Tech tip: (115 vac circuit)
The Lower High Limit is an adjustable thermostat (usually 90 – 325 degrees F) that is normally set 20 – 30 degrees below the selected plenum temperature setpoint in the controller. The setting on the thermostat is a manual dial setting on the unit itself up inside the dryer along with the reset bar on top of the unit that must be pushed if the unit is tripped out.
(Use caution entering the dryer!! The lower high limit thermostat indicates a high temperature condition unless faulty or incorrectly set!)
Potential causes of this alarm condition:
- A high heat condition caused by one or more of the following:
- Over drying the commodity causing excess kernel temperature and excess heat being recycled back up to the burner
- A fire in the cooling chamber!
- Faulty thermostat
- Too high of thermostat setting