Furnace rumble? When my furnace starts up it makes a loud boom reverberation first....

When my furnace starts up it makes a loud boom reverberation first. What does this and do I need to achieve it fixed? The furnace seems to work fine.
I a short time ago have a pipe...
Answers:    an grease furnace makes a short time noise specifically hardly clear (almost) when it kicks on. If in that is a build up of fumes , it will most definitely sort a bang or at tiniest a big POOF. I would assume that there is a delayed ignition for some defence.