We recently moved into new home, existing Thermostat is a TH5220D. I purchased a TH8110U (Programmable) The old unit has a white wire running to the W2. The TH8110U does not have a connection available for the "W2" Question is where do I wire the "White W2 Wire" into the TH8110U

Thanks :confused:

Sounds a s if you have a heat pump, W2 is usually for a second stage of auxiliary or emergency heat. I don't think the new stat you have will work.

You will need to check your heating & cooling system to be sure all the stages or levels of heat you have to find the correct stat.