I currently have a Honeywell Chronotherm III thermostat which I believe came with the house. I'm trying to replace it with a Honeywell 5-1-1 Day (RTH7000 Series) programmable thermostat. After I disconnected the old one and started the new one, I got to a point where it says "If your old thermostat has Y1, W1 and W2 wires, stop now, and contact a qualified contractor for help. What does this mean? A contractor will charge around $200 just to show up and it doesn't seem worth it. Can someone help me with this. I'd like to finish this myself.

Usually it means your new thermostat is not compatible with your old system.
It is possible one relay or two relays must be added for for proper operation OR it will not work what so ever on your old system. This is why they have professionals that deal with these problems.

It would be easier to do a better job shopping next time so you get the correct thermostat to start with. But here again a professional would have never purchaced a thermostat that would not work on your old system.
Life is a learning experience.


BTW what is the EXACT complete model number of your old thermostat. I will see if there is a conversion.

http://customer.honeywell.com/techlit/pdf/PackedLit/69-1900EF.pdf

The system doesn't show anything that specifically labels a model number. There are a bunch of numbers that look stamped. One number says Rev. 97-3829. Antoher isT8611R10009633 and the last is 199459E. Unfortunately, it looks like the previous owner of the home, while he kept papers for everything else, did not keep the manual fot this. The house was built in 1978. Thanks for your input.

Your old thermostat is a two stage heat one stage cool thermostat and might not be compatible with the new one. Read the diagram of the old thermostat below.

See here on page 4.

http://customer.honeywell.com/techlit/pdf/69-0000s/69-0348.pdf