Heat-Timer® Corporation


Residential Snow Melt Control


The Heat-Timer RSM is designed to control under slab heating systems used to melt ice or snow. It can be used in driveways, staircases, sidewalks, or other locations which must be kept clear on snow or ice. The RSM will activate the slab heating system when the outdoor temperature is low enough that ice or snow could form. The slab temperature is controlled by monitoring the difference between the slab supply temperature and the slab return temperature, the Delta T. This Delta T is then used to regulate the temperature of the slab supply.

When there is no precipitation, the RSM will remain in an idle mode, holding the Delta T which has been designed into the slab configuration. Once precipitation begins, the Delta T will increase as the slab will need more energy to melt and evaporate the moisture. The RSM will register the increase in Delta T and begin to increase the amount of heat going to the slab until the design Delta T is once again obtained. The maximum slab supply temperature is adjustable so the unit can be used on a wide variety of slab configurations, such as pavers, concrete, asphalt, or even bare ground.

  • LED display of Outside air temperature, Slab supply temperature, Slab return temperature, Actual system Delta T, Slab design Delta T and Maximum slab supply temperature
  • Outdoor air temperature sensor
  • Slab supply and return temperature sensors
  • Adjustable slab design Delta T
  • Adjustable maximum slab supply temperature
  • Outdoor temperature system cutoff
  • Slab heating system output
  • Motorized valve output
  • UL Listed

Note: The RSM comes complete with sensors.

RSM-Elite 929195-00
Digi-Elite Wiring Enclosure with a switch 929135-00
Digi-Elite Wiring Enclosure without a switch 929137-00

My outdoor sensor reading does not match the actual temperature.
The outdoor sensor measurement may vary based on its location and its sun exposure. In most cases it will never match a weather station that is located several miles away. most current Heat-Timer controls have a Trim feature which allows the sensor reading to be slightly modified just a few degrees to satisfy similar circumstances. If the difference was large, then check the sensor by disconnecting one of its wires from the control. The control should read OPEN. If not, contact technical support.

Why is my temperature sensor reading Open on the control display?
Remove the sensor wires from the control and check for continuity across the wires with and meter. If no continuity existed, check or replace the wires. if continuity did exist, then contact technical support.

Why is my temperature sensor reading Short on the control display?
Remove one of the sensor wires from the control. The control display should change and display OPEN. Then check the sensor wiring specifically around spliced areas. If wiring was good, then disconnect the sensor wires from the control and check the sensor wires with an Ohm meter. The readings should match the sensor temperature chart on the control manual. It not, then replace the sensor. If after removing one of the sensor wires the control read SHORT, then contact tech support.

  • Download the RSM-Elite in Google Sketchup 3D format by clicking here.
  • Download the Wiring Enclosure Elite in Google Sketchup 3D format by clicking here.

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