Arrived to do a performance maintenance. Installed a fiberglass merv 2 filter and removed the k&n airfilter. Set up for combustion analysis temperature split and static pressure tests. Verified operation of all mechanical and electronic components of the furnace. Found that the inducer is leaking exhaust gas. Checked blower for cleanliness and to see if there is any play in the bearings. Found that the fan is collecting dust. Checked systems heat exchanger to ensure proper venting of flue gas. Verified operation of the humidifier. Humidifiers solenoid valve is clogged. Found that when the humidifier allows air to flow through it, the furnace temperature keeps rising. Furnace is operational at this time.