I have a Rheem Criterion II Plus 2 Two-Stage 80-Percent furnace purchased August 2005. The problem is that the thermostat clicks to come on and displays heat on, but the furnace does not do anything. I have tried turning up the heat many degrees past the inside temperature but still the furnace does not come on. Any suggestions?

Call for service could be a dead circuit board.

Could be a lot of other things you could easily fix yourself. Even a circuit board isn't that hard to change. You do need to be sure it is the problem before coughing up for a new one. If the thermostat is battery powered, it could be as simple as blown fuse on the 24 volt supply. Does it respond to fan ON?

Best thing is to go to the H&AC sticky and start with the sequence of operations. Post back if you need help with the details.

Someday someone is going to get hurt because they are not qualified to follow the directions on a sticky. I have always felt that when a person has no idea where to start looking for a problem they might find themselves in a bigger problem than they can control. My answers are limited because of my state certifications and the oath I took of do no harm. I definitely do not want to talk to a lawyer long distance if you know what I mean.