Heating issues in Grayson Georgia. •During the arrival system started up in heating mode . Burners and everything came on . Completed a combustion test on the equipment. Noticed the CO levels were high checked the heat exchanger and found several hair line cracks . Took pictures. Would highly recommend replacing the heat exchanger. Heat exchanger is under warranty but the time and labor is not.... going to work up a quote for the replacement of the heat exchanger and call tomorrow.