what could be wrong w/ my furnace?

Our house is only 4 years old. My furnace will not run in the evening or at night, it does however run just fine at 7am when we leave for the day. We can get it to turn on manually by turning the thermostat off & then on, but it only runs for a few minutes, going up about 1 degree. Around 7pm the temp could be 74 in our house and by 6:30am it would be down to 54. It's almost like the furnace is on a timer that is 12 hours off. We can also get the furnace to kick on for a few minutes w/ the main power switch on the furnace. We just had someone here in August to look at our system because our Central Air stopped working. He told us then that everything looked good and we were ready for the rest of the summer and all set for the winter. Any help would be appreciated. WE NEED HELP!

Answers:
Does this thrmostat have batteries? Change em. Also too, you said that it'll kick on for a little while. Sounds like a flame sensor problem. Take the covers off the furnace. Trace the gasline into the furnace to the gas control valve and on down to the burners. Behind, or rather in front of the burners, where the flame would be is a small metal rod. This is the flame sensor. Clean any build up off with steel wool. And as said before, lose the programmable thermostat. Hope this helps.

Other answers:
Sounds like your thermostat is one that can be programmed to operate differently at different hours. Probably just needs set right. But someone probably would have found that. Would there be something causing heat on the thermostat like a light nearby or something, making it think it's warm in the house?
Sounds like your thermostat is one that can be programmed to operate differently at different hours. Probably just needs set right. But someone probably would have found that. Would there be something causing heat on the thermostat like a light nearby or something, making it think it's warm in the house?
Is your new thermostat a digital one, or a mechanical one? If it is mechanical you need to set the heat anticipator, if it is digital, pull the batteries for 5 minutes and reinstall and the temperature rise should pop up and then adjust it to 3 or 4 degrees.

If this doesn't work, I would by a cheap, digital thermostat and replace the existing one.

Is the furnace flue in the wall behind the thermostat? If it is move the thermostat.
get rid of the programmed timer on go back to the old fashioned one,where you have to set it yourself,i had nothing but problems with the new kind,just one dial is all you need,gives you heat on demand,JUST SET IT AND FORGET IT
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