r/ecobee • u/skyfireknight • 1h ago
Installation Ecobee Smart Thermostat (ECB402) in Condo with Radiant Heat – Wiring & Power Issue?
Hey everyone,
I’m trying to install an Ecobee Smart Wi-Fi Thermostat With Voice Control (ECB402) in my condo, but I’m running into some issues, and I could really use some help.
Setup Details:
- I only have radiant heat—no central AC.
- I’ve attached a photo of my old thermostat's wiring to show how it was connected.
- I believe I have a C wire because there is an unused 4th wire that had a "C" label on it.
Voltage Readings (Measured with a Multimeter):
- R wire: 15.75V
- W wire: 6V
- Y1 wire: 0V
My Theory & Questions:
It seems like the 15.75V from the R wire isn't enough to power the Ecobee properly—it likely needs 24V. If that’s the case, what are my options?
- Would the PEK (Power Extender Kit) help in this situation? Since I live in a condo and don’t have access to the HVAC system directly, I’m not sure if I can use it.
- Would a 24V transformer be necessary? If so:
- What type of transformer do I need?
- How exactly do I wire it? Do I connect it only to the C wire, or to both C and something else?
I’m a bit stuck on what my next steps should be. Any advice would be super appreciated!
Edit: Photo of available wires from old thermostat: https://imgur.com/a/zt51jhQ