24 Volt Power Adapter/Transformer,C-Wire Adapter Thermostat，Compatible with All Versions of Ring Doorbell and Thermostat for Ecobee,Sensi and Honeywell(25Ft Cable)

Works effectively to power our Nest learning thermostat with a failing battery.Before we installed this, the charge on the battery would last 7 days, then 4 days, and finally 2 days, deteriorating within a span of a month.We were away for the few days when the Nest went offline. It was 3 days before we got home, and we prayed the thermostat would still have enough reserve battery to keep the house warm in -7F until we returned. It did.When we got back, we immediately went to work connecting this adapter to the Nest. The instructions will tell you to connect the grey/white wire to Rc, but we were only using Rh, so we had to connect to Rh to get the power flowing. Once we figured that out, the adapter worked beautifully!

The product produces 24 v when plugged in. It is all it need do and what buyers expect. Here is where I diverge from some comments about its use where a jumper is suggested. It works fine but everyone's application is similar yet different. My application was a two-wire air conditioning system, central air. I installed it with a Nest. I could see with my tester 24 volts across my system wires and the two transformer wires. I hooked the transformer to C and Rh on Nest but then Nest said it did not see power to the Rc port wire. I don't believe the transformer wire and the Rc wire can be combined. To me, that is 48 volts. I did not find out because I would not do it. Instead, I added the one transformer wire to Rc and I put the Rc wire into Rh. Nest liked that, reported no errors, and everything was fine. Nest showed it saw a yellow wire (a/c) and a common wire and an Rc wire (which was really one of the transformer wires), and did not see nor show the Rc wire plugged into the Rh of the Nest. That's right. It only showed three wires. However, Nest "worked"in heat mode only. So I got it working, and I have to go from 70 degrees to 72 degrees if I really want 68 degrees for air conditioning. It is not pretty but that is not this vendor's fault. His product worked. He took the time to answer a question I emailed. I have no issues with the product. I do think smart thermostats are technology in its infancy. I don't think they work well enough to justify the hocus-pocus that goes with installation. One thing for sure is the Nest does need a common wire and this product provides that, easily. I will buy this product again because I have another Nest thermostat for a heating zone. Now I know how it works. I recommend this product.

This works great with a Sensi Lite. I had to run a wire from the thermostat into my basement, and this unit has PLENTY of wire length. You could easily run it from a second story into the basement. It seems decently made and came with some basic instructions as well as a jumper wire if you need it.

The adapter works and comes with a long cable that is thin enough to slip under the wall mount for my thermostat without issue. However it is noisy. Not recommended if you're placing it in a bedroom.

Worked perfectly for our new Honeywell smart thermostat.

Super happy with this product. I didn’t have an existing C wire for hooking up my new Wi-Fi smart thermostat. I’ve been wanting one for a long time. It gets hot in my bedroom, and who wants to get out of bed and walk downstairs to adjust the thermostat when you’re trying to sleep? I wasn’t even aware I didn’t have one until I went to install the new thermostat. It’s my first experience wiring up a thermostat, so it was a great learning experience. The C wire is basically a 24v power supply for your newer thermostats. My home is pretty old, it originally had an old style thermostat with a mercury switch.This thing is easy to wire up, it has two wires, you can use either one to send power to the C input and the other one, for me, had to go into RC. Which I assume must be for grounding. The length of the cable was more than adequate for me. Getting the wire to my thermostat wasn’t easy. I have a hole in my wall, the wires run behind the wall and down into the basement where there’s a small hole in the floor boards. I can’t believe I pulled it off, but it actually worked and it didn’t even take long with some help from my daughter. I took some fishing line and connected a lead sinker to the end and poked that through the hole in the wall. It dropped down onto the floor and I had my daughter move it around until I could see it, and grab it with a set of very narrow needle nose pliers. Once I had it into the basement I wrapped up the C wires and zip tied them so the couldn’t come lose and pulled it back up through the wall. It actually worked. I ended up running the wires along the ceiling of my basement and plugging it into an outlet down there against the wall so it can’t accidentally get yanked out of the outlet. Now I can change the temperature of my thermostat without needing to get out of bed.This thing worked perfectly for me, I have only a small amount of experience wiring and I was able to get this done perfectly and safely. The price is fair. Saved the day for me.

recently changed out my thermostats (7 thermostats at 3 properties) with the Honeywell wifi units. on all but 2 I was able to use existing wiring and get 24V into the back of the thermostats. at my older office building I was not, and with both air handlers in the attic I wasn't too excited about running a new conductor to the HW units. but both of those thermostats are on walls that have a closet on the opposite side, with a 110V outlet available. simply run the adapter wire thru the wall and into the back of the thermostats, in my case connect to the R and C terminals, plug it it and I'm good to go. I will run new low voltage wires next time I upgrade the AC units, but for now the adapter was a quick fix.

Bought one 4 months ago to use with a smart thermostat (after HVAC tech said it would be impossible to use a smart thermostat in with my HVAC and also that an adapter like this didn’t exist) and it has worked flawlessly. Bought a second one to wire a doorbell cam. Used the existing wiring in the wall, works perfectly. Only complaint is the part you plug into the wall is heavy, it stays in place but a slight bump will loosen it.