Gas and Oil Home Heating Furnaces - Loud Bang when Gas Furnace Ignites

We have a gas furnace that is approximately 20 years old. It is working fine, except that from time to time it makes a very loud bang whenever it ignites. It doesn't happen all the time, but it seems to happen more frequently when the temperature in the attic is very low or when we have the thermostat set on a lower temperature and the heat doesn't come on very often. I've been trying to research this issue and it seems that most of the time it's suggested that the burners may have to be cleaned. Is this something that we can do ourselves or is it necessary to call a technician? Also, so far nothing has happened, but is this something that could potentially be dangerous?

Hi JL:

Any delayed ignition is not a good thing. You don't want a gas builup in the combustion area of the furnace. If you mechanically inclined, you should be able to DIY. If you don't feel comfortable with it, call a pro.