During my twenty point heating inspection, I started with the thermostat. Giving a call for heating, and going to furnace to start maintenance. Temp rise of 40-70 needed, I got a temp rise of 40. House heats up to designated temperature. I checked out blower motor of any dirt or debris. It’s clean, only being a four year old system. Replaced air filter for new air filter. Owner had extra one, so just used his. Hot surface igniter not cracked or having white spots. Flame sensor still working good, no need to be cleaned. Ducting done correctly, and all runs intact. Inducer motor is working efficiently. Moved onto the upstairs unit, I shut off downstairs after I was done with my inspection. Put system in a call for heating mode. Soon as the house warmed up after thirty minutes. I got a temp rise of 46, which is perfect in my temperature rise range. House heats up to designated temperature. I checked out blower motor of any dirt or debris. It’s clean, well maintained system. Existing