Ecobee 4 installation help? Any handy people available?

I am looking to install an Ecobee 4 in my condo. There is an older HVAC system, Unilux LE600. The furnace itself does not have a C connector, only the standard G, R, W and Y. The same four wires go to the thermostat.

The Ecobee 4 requires a constant 24V at all time, which is the C. I need to find a way to create a constant 24V to the termostat.

Ecobee 4 includes the Optional Power Extender Kit. That would totally solve my problem however there is no C at the Furnace.

The Power Extender Kit essentially connects to the G, R, W and Y wires and creates a 5th wire to connect to a C, the constant 24V line.

I could buy a power adapter, but isn't there already 24V somewhere on the Transformer already? I would hate using any more hydro than necessary if I already have a source. R wire goes to the right hand side of the Transformer in this picture (Brown wire). There are the wires on the left hand side (2 dark blue), these go to two relays that are at the bottom of the picture.

Anyone handy here? I have a potential solution, but would prefer someone giving me a hand before I state what I think I want to do. (That way is probably better).


Others have tried in the building with no success... I'm thinking this can be done without the loss of fan control when not heating/cooling. I'm thinking that some people in the building have had success just that they didn't tell the property manager (only when things didn't work).

1 Answer 1


Tap the other transformer terminal

The transformer terminal on the right seems to be connected by a brown wire to R as you describe, so clearly the other transformer terminal on the front of the transformer (the left-hand one, with the purple wires hooked to it) is the C terminal. This is consistent with the wiring diagram you posted, which has wires from the transformer common to the common side of both relay coils.

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