The high limit temperature sensor is intended for two purposes, either as a slab sensor when the APS-C series unit is used for heating sidewalks, patios or drives or for ambient air temperature when the unit is used for roof and gutter melt systems.In roof and gutter applications the sensor is run outside the building and placed in a location that is out of direct sunlight and away from other heat sources such as air conditioners or
In roof and gutter applications the sensor is run outside the building and placed in a location that is out of direct sunlight and away from other heat sources such as air conditioners or vents.
In slab applications, this sensor is usually installed in conduit. If this was not provided for when the slab was poured then the alternative is to either use it as an ambient air sensor or bypass this function all together.
The High Temperature limit can be bypassed by installing a 470K-ohm resistor in place of the sensor on pins 10 & 11 Refer to figure 23 in the manual.
Above illustrates the terminal connections for the High Temperature sensor (thermistor) for the APS-4C, APS-3C, and the SC-40C Snow Switch Control Panels.