Maintenance visit number 2 no charge this visit. Performed single system heating maintenance. Removed and cleaned flame sensor. Checked filter. It is good at this time. However, we will need to bring one for replacement on spring visit. 16 x 25 x 5. Inspected electrical connections and components. Tested thermostat to ensure proper operation. Inspected the heat exchanger. Wipe down surfaces and components. Check the outdoor unit electrical and remove leaves and debris from fan area. System is operating normally.