i bought a brand new 95% eff Coleman furnace is sept, never had a problem. i live in wisconsin and this winter has been pretty mild. we have had a few cold days but everything worked fine. my house is very well insolated and the furnace harldy goes on even in the cold as the house holds the heat very well. i woke up today and my thermostat said 61 and it is set at 69. i did then realize that the furnace was running for a long time and it was last night too and it felt kind of cold in the house. i turned the furnace off and back on and it ran for about 45 min and went from 61 to 63. im not sure what the problem is today, it is cold out but i havent had this problem before, any suggestions?