Today I Performed a winter time tune up on your Dual Fuel HVAC equipment. Overall everything looks good with your system. Starting with the difference in temperature between supply and return air, I observed a return of 76° while supply was 127°F. Right where we want it. Carbon monoxide was monitored throughout the maintenance, I observed a maximum of 0ppm across the house. I did recommend the customer have some carbon monoxide detectors installed as they did not have any on hand. System startup and operation was observed for 10 minutes with all components working within manufacturer specifications. The Aprilaire 401 (16x25) filter was changed at today’s visit, using a customer provided filter. I finished up treating the drain assembly with chemical to prevent zooglea buildup. Thank you for choosing