HI THERE, My name is Bill...
I have a 1999 mobile home with a Miller Oil furnace. I have been having occasional problems with my furnaces reset switch tripping. It currently ran fine from Xmas morning until Sunday March 2. I had just got a fuel delivery (and changed from #2 oil to kerosene due to my outside tank). On Sunday I hit the reset switch and it ran the rest of the day and tripped the next afternoon (Monday). I reset it again and it ran the rest of the night but shut off at 4am. I messaged my heating professional and he told me to hit the reset again but to see if it cycled on and off like normal and it did and ran fine for a week. (I had kept the access door with the filters off for easy access.) This past Saturday as I had the access door off I decided to clean my filters, I cleaned and dried them and put the access door back on the furnace as it had been running for a week and within 6 hrs the reset had tripped again. I called the heating pro and told him and he seems bewildered and is coming on a service call today... in the meantime I took the access door back off and hit the reset again and it ran fine until this morning when it tripped AGAIN with the door off... I went from thinking it was bad fuel, to thinking it was an airflow issue to maybe thinking a blocked oil filter... any ideas?
Thank you

The pro will find out if the reset is just doing its job, that's what I think. Something other than the switch is going bad and the reset is kicking it off because of it. Could be poor fresh air intake

Intermittent problems are tough to track down. Since you've switched from fuel oil to kerosene, it's possible the kero has cut some sludge loose from the tank walls & fouled the fuel system. I'd start by changing the nozzle, filter, & pump screen (if applicable) and making sure the electrodes are set properly. It would be a good idea to check the ignition transformer as well.