ThermElect Hydronic Furnace

ThermElect Hydronic Furnace


The Steffes ThermElect Hydronic (9100 Series) is a commercial, institutional, and industrial heating system that blends hydronic heating with Electric Thermal Storage (ETS) technology. Schools, hospitals, and churches are just a few examples of facilities that have successfully reduced their peak demand, better managed their energy consumption, and saved money with off-peak ETS heating systems.


Low-cost electricity is utilized to store electricity as heat in specially designed high-density ceramic brick. Brick core temperature is regulated by outdoor temperature and heat need. The stored heat is transferred from the bricks to a water solution and circulated to where heat is needed.

The control system allows for easy customization and building load management integration. The ThermElect Hydronic Furnace is an environmentally friendly heating system offering great safety and reliability with minimal maintenance.


The Steffes ThermElect Hydronic off-peak electric heating system is extremely flexible and can handle multiple zones. Its versatility allows it to be used in, but not limited to, any of the following applications: primary space heating, supplement to heat pumps or boiler systems, pre-heating of fresh air, and domestic water heating.

Product Brochure














  • Selectable outlet water temperature (can automatically adjust based on outdoor weather temperature)
  • Built-in energy and demand management control center can be used as a stand-alone system or can receive a 4-20mA or 1-5 Volt DC signal from an external energy management system
  • Heat storage is regulated automatically or by local control based on heating need and/or power capacity of facility
  • Programmable microprocessor-based control system allows for application customization and self-diagnostics
  • Digital display provides operating and diagnostic information
  • Super insulation package ensures low surface temperatures and minimal static heat dissipation
  • BACnet communication and control interface available
  • Integrated SSR control to provide variable input power regulation


BACnet Control

Steffes commercial furnaces are available with a BACnet control option. It can be easily integrated into most building automation systems. The BACnet control provides building managers full control and visibility of the heating system’s operations.

  • Real-time system monitoring
  • Full thermostat control
  • Monitoring of heat storage levels in the brick and all system temperatures
  • Remote configuration, testing, and adjustment
  • Service requirement alerts

BACnet Control Product Brochure

Outdoor Temperature Sensor

This accessory provides outdoor temperature information for automatically regulating brick core temperature.

  • Comes standard with all furnaces, optional add-on control with room units
  • Can be wired directly to the heater or to a Steffes Power Line Carrier (PLC) load management control system
  • If direct wired to the heater, one sensor is needed for each heater
  • If direct wired to a PLC control system, only one sensor is needed for the entire application
  • 40′ low voltage, 2-conductor cable
  • Mounting bracket provided or can be mounted into a knockout using its ½” male pipe thread nipple
Time Clocks

This microprocessor module provides peak control signals directly to room units and furnaces. In addition, it can provide room temperature set back signals to the room units.

  • Directly connected to heater’s internal control board (one/heater)
  • 5/2 Day programmable
  • Allows up to 3 separate weekday and weekend peak time settings
  • Provides up to 4 separate weekday and weekend room temperature set back time settings (room units only)
  • Capacitor power back-up (3-days)
  • Override capability

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