- Condition: The dryer has detected a temperature in the heating chamber higher than the over temp band setting on the Burner Settings screen for more than 5 minutes as allowed by the hard timer in the controller program.
- Alarm Action Taken: COOL DOWN
- Component: RTD (Resistance Temperature Detector), Modulating motor & “Butterfly” valve
- Location: The RTD 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 airduct into the heating chamber and is then ran vertically usually along side of the internal access ladder in the heating chamber.
The modulating motor and butterfly valve are located on the fuel trane at the bottom of the dryer.
Tools Required for Service:
- Voltage/continuity meter (to check ohms & voltage)
- Small Phillips screwdriver (to loosen screws on mod motor lid)
- Wire strippers (if replacing sensor or refreshing connection)
- Replacement small wire nuts or crimp connectors
- 3/8” wrench or impact w/3/8” socket (to loosen p-clips if replacing RTD)
Tech tip: (RTD 1000 ohms @70 degrees device) (Modulating motor 115 vac input w/24 vac internal transformer)
The RTD used for this function is an “averaging” unit. It senses temperature along the entire length of the unit and sends back the “average” temperature readings/resistance to the controller.
Potential causes of this alarm condition:
- Too high of gas pressure from vapor regulator causing too much temperature rise with very little modulating adjustment from the motorized gas “butterfly” valve
- “Butterfly” valve stuck open or faulty
- Faulty modulating motor
- Open circuit on RTD reading 350 degrees
- Corroded/loose connection on RTD
- Faulty RTD