Hello, My name is XXXXX XXXXX I will do my best to help you today.
Does the circulating blower ever kick in?
Do you get a flash code on the control board LED when it fails?
Can see and control board
It's behind a black cover
located behind the bottom door of the furnace mounted on the blower housing
It is most likely giving the 3 blink code for limit open. It could be pressure switch blink code of 2 but most often for the description you are giving of what is happening it is the limit
This limit senses the temperature inside the heat exchanger and if there is an issue with your airflow the heat isn't pushed out sufficiently enough and the limit opens shutting down the burners and running the blower until it gets the heat out and cools to limit back to it's reset temperature.
The reason I asked about the blower motor is that when it happens very soon after ignition every time about the same time it is because the blower motor never kicks in to push the heat.
Other reasons this will happen is a dirty filter, dirty evaporator coil that sits on top of the furnace, blocked return or supply runs, or simply a defective limit
Going to start the furnace and look for blinks, will take about 10 min
Your system isn't a damper zone system is it? Sometimes on a power damper system the dampers may malfunction and be sucked close causing no air to be pushed out of the furnace and cause the limit to open.
I bypassed the blower saftey switch so I could watch the control board and the furnace kept running normally. Since this cover bypasses the filter and allows unrestriced flow the furnace was able to keep cooler. I assume the filter is the problem, however it didn't look that bad.
Since this model is only 80% efficient, could you recommend a high efficiency replacement?
you may have some blocked returns that is causing less air to enter the system.
Any system 92% efficiency plus 2 stage heat preferably will gain you the most efficiency. We are not really suppose to promote one brand over another that is not our purpose here. All of the brands are well and good just make sure you are getting quoted the premium end of the brands line and not the builders grade.