UL Certified Thermostat C Wire 24V Transformer, White Adapter Compatible with Honeywell, Nest, Emerson, Ecobee, Wyze Thermostat and Most Doorbells (26FT Power Cable)

First, this did NOT successfully power the new Gen 4 Nest thermostat, the device continued to say low power. I swapped in the Google nest power adapter which supplies 33.57v of power into a 24v system, which is what the Gen 4 device needed, not the fault of this transformer however. Now on to the review...most HVAC techs are going to tell customers to not use Nest/Ecobee style thermostats because they generate too many sales calls to come back and fix the homeowner's handywork. You need to understand the basics of how the 24v system works, wiring color codes, and how and why your thermostat sends a call to the contactor in the unit for A/C for example. This product does nothing but offer a constant 24v supply to power a fancy thermostat on units too old to have that in place. The C wire that is mentioned frequently is just a common wire that gives the 24 volt power a place to return and complete the circuit. In a forced air/Nat Gas heat and A/C example, you would simply place one of the white wires from this product to the C terminal and one to the RC as the picture on the listing shows. The RC and RH terminals are the two "hot" lines in this example. RH + green runs the fan, RH + Yellow runs the compressor, RH + White runs the Heat, and RC + C powers the fancy thermostat. Your thermostat will combine inputs for you to make everything work, for example RH + Y1/G is the Call to run the AC compressor and air handler fan together to pump that chilly air goodness all over your house. Hope that saved someone a sales call because "this Chinese product dont work good".

Worked for what I needed New thermostat needed a extra power source this was a simple install and fix

Worked great for nest thermostat!

This was a UL listed device that is sometimes needed on thermostats especially the smart thermostats that requires you to have the common wire. This adapter provides that common wire connection and it is overload protected also.

BEWARE. I installed this today as an auxiliary power to my Nest. I had another plug but I wanted to run a new one so I bought this as the previous was no longer available. After installing just as my other was I left the house for two hours. I hadn’t yet pushed the furniture back in place and when I touched the unit plugged in it was scorching hot and smelled of melting plastic. I immediately unplugged it from the wall but you could hear something moving/rattling around? If you turned it slowly it almost sounded like sand or little balls? I have no idea but I disconnected and put it outside. It was too hot to put in a plastic trash bag. I reinstalled the one I had before and it’s fine, so it’s not my outlet.I have no doubt this could have caused a fire in my home if I’d not realized the issue so quickly.

Works fine with my GE CYNC Smart Thermostat. I followed the wiring diagram from the product pictures, I don't think it came with any instruction manual.

We are very happy with the product. It works as advertised.

Got yourself an In-Wall Heating Unit? Just bought a Google Nest Thermostat and it isn't compatible? This will fix the issue. The wires are so long that it really doesn't matter how much you mess up at first trimming it, just wrap it snugly around the existing wire. When you get it down and plug it into its corresponding slot on the Nest and into the socket, you're golden. Enjoy your smart home automaton.