Performed a complete heating system maintenance and inspection. 2022 Lennox gas Inspected and tested all electrical components and safety controls on the indoor unit; all components tested within manufacturer specifications. Verified system temperatures: return air temperature measured at 67°F; supply air temperature measured at 139°F. Confirmed air filter was recently replaced by client; filter size is 20” x 25” x 4”. I visually inspected the outdoor unit, The outdoor unit could benefit from having a surge protector installed to protect the unit from lightning strikes, black outs and other types of surges in power. It comes with a 3 year warranty and $10,000.00 insurance policy for repairs if surge protection were to ever fail and components be come damaged after a surge in power. Confirmed system was operating properly and heating upon departure. System Status: Operating normally at time of service