Performed single system heating maintenance on a 2017 Propane Lennox system. Checked amps, filter, electrical, gas valve, cleanliness, and safeties. System is heating to manufacture specifications with recommendations for cleanings and filter upgrade. Recommendations 1. Current filtration is allowing air to bypass the filter. I recommend upgrading to the Aprilaire filter for true filtration. 2. The ducts have a reasonable amount of dust build up. I recommend cleaning the ducts to better the air quality and to kept from the rest of the system getting caked with dust. 3. The blower has an excessive amount of dust build up on the blower wheel. This causes the blower to have to work harder to perform its normal duties. This can result in premature failure.