I have four wires going to the thermostat. So I installed the PEK 5 wires out of the PEK to color matching terminals in the furnace block. Going into the PEK were the four wires from the thermostat, R,G,W,B. Blue went into the yellow connection on the PEK. The blue wire was originally connected to the Y connection on the furnace block connections. Installed the Ecobee 4 with the following wires per Ecobee documentation, R -> RC, G -> C, W -> W1 and B -> PEK. When I install the Ecobee 4 thermostat and going through the initial setup it only recognizes the RC and W1. I took the Thermostat off and pulled on the wires to ensure they were installed and also took them out and trimmed some off to ensure I didn't have some wires broke in the insulation. The previous thermostat worked so I know the thermostat wire is good and it worked after I reinstalled the old thermostat, any ideas as to what could be wrong?

Here is the wiring before the PEK.Wires from thermostat went R->R, G->G, B->Y, W->W enter image description here

  • Can you post photos of the wiring, especially at the furnace end? – ThreePhaseEel May 4 '19 at 23:35

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