So, pretty straightforward question. Just looking to see if I possibly have bigger issues than I may have thought this morning. Is the Thermostat powered by the HVAC unit? (IE- if the batteries in the thermostat die, will the thermostat still be powered?) This morning, I woke up to a hot house at 430am (It's been a heatwave). I walk out to the thermostat to notice the screen is dead. So, I attempt to pull the cover off to check the batteries (It's a Honeywell programmable). Instead of accessing the batteries, i ripped the entire face off of the unit. (Morning luck) Thinking that the thermostat is always powered by the unit, I went to check breakers in the basement. I didn't see anything tripped, and the outlet attached to the side of my HVAC unit had power. I went upstairs and removed the thermostat, replaced the batteries, and reinstalled. Air conditioning kicked on immediately. The Thermostat had the correct time/day and ran the scheduled cycle I had installed. Was it just a battery issue? Or do I have something possibly deeper going on?

[left][left]Hello, Need help wiring nest e to trane xl80. Problem is I have no c wire at the existing stat, but there are 2 wires connected to the b/c terminal at the furnace. There is an unused blue wire at the furnace and going through the wall to the stat which is also unused. My existing thermostat has 4 wires and no c wire. It has a G, W, Y and R with jumper to Rh. Nest says just to connect the 4 wires and don’t use c. My question is where are these B/c wires hooked up to at the furnace and why is nothing using the c terminal at the stat? And couldn’t I just put the unused blue also on the B/c terminal at the furnace and attach it at the c terminal at the stat? Any advice would be greatly appreciated! regards, RM[/left]