How To: Control Baseboard Heat With Zwave Low Voltage Thermostat

We are regularly asked to control and automate line voltage 120V or 240V baseboard heating.  All of the readily available Zwave thermostats from major brands like Honeywell, RadioThermostat, Current Innovations, 2Gig or Evolve are designed for typical low voltage 24V heating and air conditioning systems.

Edit:  as of 2016 we are now carrying a Stelpro Zwave Baseboard Thermostat:



This article will remain to explore how to control 120V and 240V baseboard heat with a low voltage thermostat.

Let’s look more closely at the problem.  The baseboard or line voltage heater is running at 120V or 240VAC.  All of these Zwave thermostats are 24VAC.  There are two simple ways around this issue:

  1. Power the thermostat with a plug-in AC transformer like part# TP2024 and then use a relay connected to the output of the thermostat, such as Aube part number RC840 or your electrician’s favourite relay or contactor that they can recommend and/or install.  In this case you’ll plug-in the power supply somewhere near or accessible to the thermostat, and run a low voltage wire from the transformer to the thermostat.  Then you will run low voltage wire from the thermostat to the relay, and the relay will connect to and control your high voltage baseboard heat or load.

    Low voltage thermostat with plug in power supply and relay controlling high voltage load.
    Low voltage thermostat with plug in power supply and relay controlling high voltage load.
  2. Use a relay board that also provides power to the thermostat.  We recommend Aube part numbers RC840T-120, RC840T-240, RC840T-347 for 120VAC, 240VAC and 347VAC loads or heaters respectively.  The relay will typically install at or near the baseboard heat or anywhere in line feeding the baseboard(s).  Then low voltage thermostat wire will be run from the relay to the thermostat.  This wire will both power the thermostat and control heating. Using low voltage thermostat with 240V baseboard heat


By using either method above, it’s fairly simple to use your favourite low voltage Zwave thermostat to control baseboard heat at 120V or 240V.  Once your Zwave thermostat is connected and working, you can then enroll it in to your favourite automation controller such as VeraEdge, Hometroller, Fibaro or Zipato to schedule control your baseboard heat from anywhere!



IMPORTANT NOTE:  This is article is written for interest only.  When dealing with line voltage / high voltage loads like this please check your local building and electrical codes and work with or hire an electrician or HVAC pro to install the product for your own safety and to ensure you will be covered in case of an insurance claim!  We do not recommend do it yourself installations on 120V baseboard heat and relays.