Outdoor temperature thermistor 'may' be reading too low, but this will bring the system into propane only at a warmer outdoor temp than the 30⁰ setting The fact the house got cold indicates the propane furnace stopped working The stored faults were all a 2 code "# of retries exceeded" Cleaned flame sensor Found burner ignition not fully reliable crossover Pulled and cleaned burners Intake and exhaust might have been covered with snow on the roof, too Furnace is operating normally at this time Invoice is payable online