I have a 2-3 yearold keeprite that starts up for a few seconds then shuts down. This is when heat is not called for. If I turn up the thermostate to a higher temature so heat is called for it starts up and heats till proper temp is reached and shuts down as requested. Now assuming the thermostate is giving false command to start then immediately telling it to stop was my first thought, so I disconnected the thermostate "Honeywell RTH7000 series" with the intent of buying a new one. Before I got away the furnace again attempted to start (no thermostate) flame kicked in and then shut down within a few seconds. This seems to repeat itself several times then givesup, waits for a few hours and tries again. If at anytime I turn up the thermostate to call for heat it works perfectly. I have not seen any error signals on the flashing light. So the furnace heats properly when it should it is just that it seems to try to heat when it should not and then immediately corrects itself. Weird and annoying when you wake up to this attempt several times a night and even during the day having your furnace start and stop for no reason. I installed this furnace myself 3 years ago and this just started two weeks ago. Any suggestions? Thanks.