Complete 2 system furnace repair and preventative maintenance check. Change both filters, check safety and operations. Find both 10-year-old Lennox furnace operating with leak/worn flame sensor. Find the main furnace under-fire. Complete combustion calibration for the main heating system to improve temperature and efficiency. The customer wants to keep a check on the flame sensor. Suggest inline water protection for both systems in the attic. Suggest an air purifier system to improve air quality.