How to Power a Smart Thermostat Without Connecting to a Furnace
I am not a licensed electrician. If in doubt or have specific questions about electrical work, consult a professional. While I will not undertake large electrical projects nor offer advice about them, I will offer advice regarding smaller electrical DIY projects such as wiring a lamp, replacing a power tool cord, installing a new outlet or switch, or the project below.
A couple of years ago, I wrote a sponsored post about a smart thermostat (read more about it here) and I really loved it! One of the best features is that it not only displayed the indoor temperature, but the outdoor temperature as well as the current weather and the forecast for the next day. Since we no longer have a furnace to use the thermostat, I wanted to figure out how to power the smart thermostat without connecting it to a furnace so I could use the thermostat as a weather station…
Awhile back, the compressor died in our air conditioner (the day before I started a new job) then a year later, a tree fell through our house basically severing the house in half and leaving us with no reason to have central heat or air (thankfully, I didn’t have the air conditioner repaired or replaced!). I was left with this fabulous smart thermostat and didn’t want to get rid of it, especially since I knew there could be a way I could use it as a sort of weather station if I could find a way to supply it with power.
A quick internet search led me to a power supply/transformer (<– affiliate link!) that plugs into a regular outlet for heating and cooling systems that do not have a common wire, or “C” wire to power a smart thermostat . Let me explain…
In order to use a smart thermostat to control the heating and air conditioning unit, it needs power. Most newer furnaces are equipped for using new technology such as smart thermostats but older furnaces are not and therefore, do not have the C wire to power a smart thermostat. There are a few companies that have taken this into consideration so that smart thermostats can be used by all consumers regardless of the age of the furnace. The power supply/transformer is made for smart thermostats and has two wires – one going to the C wire terminal and the other going to the RC terminal, then plugs into a wall outlet for power. The remaining wires from the furnace connect to the thermostat, as usual. (Refer to the manufacturer’s installation instructions for your specific thermostat!) The wire from the transformer can be run through the walls or secured alongside wall trim using tiny cable clips (these came with the transformer.).
Once I connected the wires to the thermostat, I secured the thermostat base to the wall taking care to not tighten the screws and crush the wires.
I plugged the thermostat unit into the base and let it power up.
This power supply was exactly what I was looking for to use my smart thermostat as a weather station! I still love the idea of knowing the temperature of the indoors and outdoors at a glance!
Plus, there is an ambient glow behind the thermostat when it comes on.
Have questions about how to power the smart thermostat without connecting to a furnace? Leave a comment below!