Performed yearly maintenance and safety checks in 2010 Bryant furnace. Found furnace running with 33 degree delta t. Found 9.61 %o2. Found 443 ppm co in flu on low heat stat made call for medium heat. Found ppm in flu up over 800 checked flu termination. Flu is clear of blockage. Called for pricing and availability. Repair is hm42 customer chose to replace furnace. Chose 987 furnace to be installed tomorrow.