Performed annual heating maintenance grass valley. 3 yr split garage side yard. Changed filter at unit, checked to make sure that their wasn’t filters being used in the grills, there are not. Visual inspection of unit ok. System is a high efficiency unit, draining ok at this time. Cleaned burners and flame sensor, burners clean. Hot surface ignitor at 55ohms. Variable speed motor, ok clean. Even with finding loose insulation trying to get sucked into the blower. Electrical connections ok, no burnt connections. System doesn’t have a surge protector.