Heating Unit Problem

[Hobbes44]

I noticed a problem when I would get home from work and the house would be freezing. I normally have the thermostat set so it will kick on at a certain time. So I changed the thermostat thinking the problem was that. After installing a new one, I experience the same thing.

The heat works, however, not correctly. For example if it is reading that it is 71 degrees in the house, I can not raise it to 73. When I do the furnace starts up and then turns off. But when the temperature drops to say about 67-68 then it will kick on like normal and stay on until it has reached it programmable temp. But again, if I was to raise or override the current temperature, it will not turn back on. It seems the glow/ ignitor stick inside the furnace glows up, the burners get going, and then turns off.

Any suggestions of what might be the case? It is a Lennox Elite unit. Any comments would be much appreciated.

[pacnw]