Furnace and Chimney woes, are we going to be poisoned?

its not unusual for frost to form on top of your chimney in cold weather,,,u should go down to where your furnace is and if its unusually warm and humid then your chimney may not be drawing,if this is the case shut your htg unit down and call your gas co,,they will come out at no chg and ck for gas leaks,,,u can have a yellow flame and no co,,u can have a blue flame and have deadly amounts of co,,,i have seen this up close and personal,,,repaired gas appl for 38 yrs for a major utility.don't like to step on toes but when lives may be at stake i will,,sorry!!!