Originally Posted by yuri
Check for 24 volts between the R and C on the subbase. With the power On. Yes/No?
Did you put batteries in to the new thermostat and or remove the isolator tab from the end of the batteries (keeps tstat off when in box B4 being sold).
So I hate to admit it but I hadn't put batteries in to it (I did that just moments before reading your post). The old one is the exact same design and had a spot for the batteries but there were none in there and it worked fine. But I put batteries in to this one and now everything is working great.
But that leads me to believe it's getting power from the batteries and not from the house. Maybe this model doesn't support being powered from the house?