Wiring guide
ecobee Smart Thermostat Enhanced wiring for k wire (Honeywell wire saver)
This setup is possible with the ecobee Smart Thermostat Enhanced, but a professional install is recommended.
A wire on K means a Honeywell wire saver module is installed at the furnace, combining fan and cooling on one wire to free up a C wire. Only some thermostats understand K. Read the full k wire (Honeywell wire saver) guide for how to confirm your setup and mistakes to avoid.
Wiring diagram
Detected system: 1-stage heat, wire saver on K (fan + cooling), C wire present · 4 wires
ecobee Smart Thermostat Enhanced
Pro install recommended| Wire | Color | Job | Connect to | Note |
|---|---|---|---|---|
| R | red | 24 V power | Rc | |
| C | green | Common (C wire) | C | |
| W | white | Heat, stage 1 | W1 | |
| K | yellow | Wire saver (fan + cool) | Don’t connect | No K terminal. A pro must remove the wire saver and restore G and Y. |
Install steps
- Turn off power to the furnace/air handler (switch or breaker) and the AC condenser. Confirm the old thermostat is dead.
- Photograph the old wiring, then label each wire with the letter it came off. Ignore short jumpers.
- Connect each wire to the ecobee Enhanced terminal shown above. Cap unused wires one at a time.
- Restore power and finish setup in the app.
- Test heat, cool and fan. If a breaker trips or equipment runs nonstop, power off and call a pro.
What you need
- ecobee Smart Thermostat EnhancedThe thermostat itselfCheck price
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Confirm against the official ecobee install guide. The app also checks your wiring during setup.
Frequently asked questions
Where does each wire go on the ecobee Enhanced?
R → Rc; C → C; W → W1; K → not connected.
Do I need a C wire for the ecobee Enhanced?
You already have a C wire, so no adapter is needed.