Gas furnace burner cycles on and off
Our gas furnace burner cycles on and off several times while the thermostat is not satisfied. The burner will run for 5 minutes, and shut off for about 2 minutes and then turn back on for 5 minutes, while the fan runs continuously. A HVAC professional was out and initially thought there may be a duct work problem, the furnace has been running with current duct work and without issue for 10 years. Another HVAC professional, same company, came out and did a limited check of airflow out of the duct work and determined everything was fine and he replaced the limit switch and said he believe all is operating appropriately. He also stated the temperature differential was appropriate for the furnace. Today I sat and watched the furnace, what an exciting Saturday, and I noticed the burner cycles on and off while the blower continues. I am unsure if this is normal. I have tried to do research and found one site said the burner should cycle for 2-3 minutes and another that said if the burner cycles off while the thermostat is not satisfied there could be serious problems. Any thoughts?