Automatic Snow/Ice Melting System Control Integral GFEP

The APS-4C Snow Switch when used with one, or more, compatible sensors automatically controls snow/ice melting heaters for minimum energy costs. Applications include pavement, sidewalk, loading dock, roof, gutter and downspout snow/ice melting in commercial and industrial environments. The APS-4C is interchangeable with the earlier APS-4.

The Snow Switch Model APS-4C Snow/Ice Melting Control is designed to be used with another compatible heater control.


The adjustable hold-on timer continues heater operation for up to 10 hours after snow stops to ensure complete melting. The optional RCU–4 Remote Control Unit can be located where system operation can be conveniently observed. It duplicates many of the APS-4C front panel functions.

The APS–4C provides advanced patented and patent pending ground fault equipment protection (GFEP) as required by the USA and Canadian National Electric Codes. The GFEP automatically tests itself every time the heater contactors operate and once every 24 hours. The trip current can be set at 60 or 120 ma via a DIP an internal switch or retained at the 30 ma default value. As an aid to troubleshooting heater ground faults, the APS–4C provides an output that can indicate the ground current on a service person’s portable DVM.

The calibrated 40°F to 90°F (4°C to 32 °C) high limit thermostat prevents excessive temperatures when using constant wattage and MI heaters. It also permits safe testing at outdoor temperatures too high for continuous heater operation. The temperature sensor is included.

The APS-4C provides a complete interface for use in environments supervised by an energy management computer (EMC). This feature can also be used for general purpose remote control and annunciation.

All sensor and communications wiring is NEC Class 2. This simplifies installation while enhancing fire and shock safety. The APS-4C can interface up to six sensors from the CIT–1 product family. More sensors provides superior performance by better matching the controller to site performance requirements.

Features & Benefits

  • Automatic snow/ice melting control
  • Satellite contactor interface for larger system
  • Energy management computer (EMC) interface
  • Accommodates MI, constant wattage and self-limiting heaters
  • Multiple sensor capability
  • Advanced patented and patent pending ground fault protection
  • Heater hold-on and test capability
  • C-UL-US
  • Simple to install and operate
  • Low energy costs
  • Minimum energy costs



All the efficiency and controls you could ask for in a snow switch. This unit will turn on your system only when it is cold enough to snow and there is moisture detected. Includes the required GFEPD protection.

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Required Sensors for the APS-4C:

Model CIT™–1 General Purpose Snow Sensor
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Model GIT™–1 Gutter Ice Sensor
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Model SIT-6E Pavement-Mounted Snow and Ice Sensor
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