My Furnace Makes a Loud Boom

Topic: 
Heating and Cooling
Question: 

My furnace makes a very loud boom when it is igniting the furnace. It seems to happen more when the furnace is cold first thing in the morning or the first time it comes on in the day. The year is not on the furnace, however, I did find these numbers 13p28086. 80,000 BTU GAS BOILER. Any help that you could give me on this matter would help me greatly, for I cannot afford another furnace. Also, If you could also give me info on cleaning this type of furnace. Thank you

Answer: 

THIS COULD BE A VERY DANGEROUS SITUATION!!! This is not a 'do it yourself' project! You must have this furnace inspected ASAP by a local company which specializes in gas heating systems. My concern about the situation you describe has moved your question to the very top of a growing list of