Introduction
The ecobee Smart Thermostat Premium thermostat was on sale for $239.98 on Amazon, which was close to an all time low. Enbridge was also offering a $125 rebate for geting a smart thermostat. I decided to take advantage of the sale and rebate and replace my old Honeywell thermostat.
The reason I went with the Premium version was that my system didn't have a C wire, and the Premium version has a power extender kit included.
Examining the Wiring
I removed the old thermostat and examined the wiring. I had a total of 5 wires, but the strange part was that there were two R wires. I had the following wires (with the typical functions in brackets):
- W (Heat) - White
- Y (Cool) - Blue
- G (Fan) - Green
- Rc (24V power) - Red
- R (24V power) - Red
I couldn't proceed with the installation, so I contacted ecobee support. They had me open up the furnance and take a picture of the wiring.
The support agent had me trace the two brown wire bundles and the black wire (white arrows in the picture) to the control board.
The black wire was spliced twice, once using a wire nut to convert to white and red (sheathed in a brown sheath). It was then spliced again using another wire nut to convert to a black and white wire (sheathed in a brown sheath), where only the black wire was connected.
It then went into the joist space and followed the ductwork out of the furnance room. The two brown wire bundles went into the joist space as well but in a different direction towards the breaker panel. I reconnected to another agent and they pointed out that the thermostat had an blue wire while the furnance had an orange wire. It was also strange that the two red wires had a jumper with each other. I was able to trace a splice in the drop ceiling where the entire bundle of wires was spliced (including converting the orange to blue). However, this didn't explain the two R wires.
I noticed in the drop ceiling that two brown wires went up and likely went to the thermostat. I pulled the wires further off the wall and found one of the brown wires, however the wires that came out of it were red and white (with white not in use). This didn't make sense as if it was the same black wire that was spliced twice, it should have been a black and white wire. The other four wires (white, blue, green, and red) matched the spliced bundle in the drop ceiling.
I theorized that the other red wire (with the unused white wire) was spliced once more between the furnance and the drop ceiling. I couldn't verify this as the ductwork was in the way and I couldn't get above it to check. I decided to purchase a wire tracer the next day at Princess Auto to trace the wires since I didn't want to blow the furnance panel by testing.
From what I could get so far, the wiring was strange and I couldn't understand why the installer would have done it this way.
