On Sun, 9 Oct 2005 17:22:24 -0500, "Rod Dahl"
wrote:

I have a 4 year old Lennox gas forced air furnace. When I get up in the
morning and turn the thermostat up from say 68 degrees to 72 degrees, the
furnace fires up and heats the house up to 70 degrees and shuts off. The
digital thermostat still displays the icon calling for heat, but the furnace
stays off for 5 or 10 minutes and then starts up again and finishes heating
the house to 72. After that, it maintains the temperature perfectly.
It seems the thermostat is working properly because it shows that it's
calling for heat. Why would the furnace shut off prematurely like that?
Thanks


Its a common occurence. The heat exchanger heated up faster than the
fan could kick in cool it to below the upper shut off temperature. By
the restart all the parts would have warmed up for the sensors to work
correctly.