First, I know nothing about heating. But our heater is old and when our central heat is about to kick on, it makes about 4-5 clicking noises (like an ignition lighting sound) and then a huge burst of air sound and makes a loud noise. It never used to make the burst of air and the loud noise. Then the heat is on and it's normal. I always thought it was supposed to just gradually turn on and not make that burst of air. Any ideas or suggestions?

Much appreciated!