Performed preventative maintenance for gas furnace. Replaced the Merv 11 20x25x5 air filter that the customer supplied. Inspected all the electrical components. Confirmed proper high and low voltages. Cleaned the burners, flame sensors and burner compartment. Tested all the safeties for proper operation. The system has a bypass humidifier that has not been turned on so it has a new panel. Next fall the #35 water panel will need replacement. Performed a combustion analysis on the furnace. System is operating at 82.3% efficiency with a CO level of 26ppm. Customer asked about the tankless water heater as well. The unit is only about a year old. Doesn’t need service at this point but doesn’t hurt to have maintenance on it next year as well as flush the system to keep scaling down. System is a Bradford white tankless unit. System is operating properly at this time. Customer would like to talk to us about system for heating only in the basement since his office is there and he has no basemen