Honeywell Home C-Wire Adapter for Honeywell home Wi-Fi Thermostats and RedLINK® 8000 Series thermostats THP9045A1098

TL,DR: Using this with an Amazon Smart Thermostat and works fine.Though I did have a small moment of panic initially after installing everything and setting up the thermostat itself. As I was admiring my work and watching the thermostat come to life and wake up in its new home, it began “clicking on” and then immediately going blank for several seconds. At first I was thinking this may be part of the set up… until it didn’t click on again and was unresponsive in every way. At this point I just knew for sure I fried something, was going to have to call a technician out, and they were going to tell me I’d have to replace my entire system for thousands of dollars. I grabbed my multimeter and verified I had power coming to the furnace and then checked the small 3 amp fuse at the control board which was blown. I switched that out with one I luckily had on hand and everything came back to life as I threw the breaker back on. That was yesterday afternoon and everything has been working fine ever since.Further things I learned during this process:- What each wire does on a heat pump system (hence the pic with them identified).- This adapter combines the fan and condenser wires to free up a wire to be used as the C-wire- The C-wire is effectively the return for the 24v to the thermostat to complete the circuit (think chassis ground on a car or neutral on a home circuit).- If you have an unused wire on your thermostat cable, you don’t need this. Just hook that unused wire to the C-wire in your furnace (look for the blue wire coming from your outside unit and verify where it goes to the control board in the furnace) because even if you get this, you still gotta find a C wire to connect it to.

Works good so i can have a smart thermostat

Worked great to add the extra wire so I could run the fan, works great on my Honeywell Thermostat

works great

It worked only 2 months what you paid what you got basicallyNot worth to put it in long term

This converter was easy to install and came with easy to follow instructions. No issues getting the Honeywell Wifi thermostat connected to our hvac system. Our home was built in the 70s and naturally lacked the 5th wire to connect a 24v line to the thermostat. I was skeptical when buying this as it seemed too good to be true to get that power wire this easily. No issues!Something I ran into during install that wasn't really covered in the wiring instructions: My furnace is an HE model, the yellow wire was split off the main circuit board on the furnace and it was ran to a float safety switch, then off to the thermostat from that switch. Make sure you wire in this box after the switch not directly off the circuit board. This float prevents the unit from running if it is full of water and not draining.

I'm sure it works well but under further review I decided to just replace the old wire with a new 18/5 wire to pick up the "C" wire. Therefore I returned it.

This was not difficult to install. Just follow the directions closely. Works great on my Anazon smart thermostat.