Okay I have a rheem furnace and it was working fine just a couple of days ago. Yesterday I woke up and it was 57 degrees in my house and I could hear the exhaust motor running on the furnace but there was no air coming out of the vent and the burners were not on. I checked a few things and determined that it must be the vacuum switch.
I decided to replace the thermostat to match my other one before I bought a new vacuum switch just to rule that out and now the blower motor and the exhaust motor will come on at the same time and about 30 second later I can see the igniter glow but still no gas and no flame. Is the gas valve bad, or is there another problem?
Its okay to upgrade your equipment but I would hold off on doing that for when the system is working right. Wire you old tstat back up and verify everything is behaving as before. Next check you temp sensor as that is part of your ignition sequence.