Hi, I have an older gas Furnace (8 yrs)? And it seems to run fine when we first turn it on via the Thermostat (ie, turn on, set temp to... ). Warm air blows out upon initial startup and maintains this heat up until the desired settings.

However as the hours and day goes, on, the thermostat of course, turns on the furnace again if the temperature falls below the set desired setting. When this happens, the air is normally cool or sometimes even cold, ---- and of course, if we're away for awhile, the house is actually colder than normal with the furnace running constantly blowing cold air.

We can usually fix this , but turning off the thermostat, waiting 10 minutes or so, and then turning it on. But ideally we'd like to live with a normal automated system :)

I'm willing and ready to bring in professional help, but was wondering if any experts on this board could provide some insight - maybe it is a quick fix?