Can I Use A Smart Thermostat In My Home?

Before purchasing any Smart Thermostat you should be asking yourself, is my home's wiring compatible with a smart thermostat? As you may be able to tell, not all homes heating systems are wired the same. Home thermostats and HVAC systems are wired in two ways; Line voltage, and Low voltage.

Home Thermostat Types

Line Voltage

A close up of thermostat electronics

Line Voltage or High voltage home thermostats are typically used for baseboard heaters, electric room heaters, radiant heaters, and forced fan heaters.

High voltage ac thermostats typically come in 120V and 240V varieties and operate on a room-by-room basis, meaning each room has its own thermostat.

Low Voltage

Close up of thermostat wiring

Low voltage, as the name implies, run on much less power, around 24V.

Low voltage systems are set up to run the entire heating and cooling system from one thermostat, so changing the settings will affect multiple rooms.

Check out our blog on line voltage vs low voltage for a more detailed comparison.

Wiring Guide

Thermostat wiring colors and terminal labels

The easiest way to tell which kind of thermostat you have is to pop the faceplate off your thermostat and look at the wires.

Line voltage thermostats will only have 2 thick, braided wires.

Low voltage systems will have anywhere from 2 to 9, small gauged wires.


Electrical tester and tools

If you have determined your system is low voltage, you will need to locate the C-Wire.

The common wire is responsible for sending power to the thermostat, and without it, the wireless thermostat won't function properly.

If no C-wire can be located, one can be installed, but HomElectrical recomends leaving any wiring installation to an electrical professional.

In the USA, 90% of homes are using low voltage systems like a central furnace or a heat pump or a boiler as their heating/cooling system. Only about 10% of homes are using line voltage systems like a baseboard heater or a forced fan heater or a convector or a radiant ceiling heater.

Conclusion: Smart Thermostats

In the end, most wireless thermostats, the Nest and Ecobee for example, are low voltage. A line voltage system really limits your options in terms of smart thermostats.

Stelpro, with Z-wave technology, does have a selection of Wi-Fi thermostats that are line compatible, unfortunately, you will have to purchase a smart thermostat for each digital thermostat or an analog thermostat that you are replacing.

Tyler Karstensen
Tyler Karstensen

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