I have a loud noise that is drowning us out in our house. We have a forced air furnace.
When the furnace comes on the first sound we hear is similar to an idling car. Then a loud vibration sound starts. Fairly regular, but not entirely. Then you can hear the gas ignite and finally the blower. That second sound is really the problem though. It drowns everything out. It seems to be related to a little turbine-looking wheel that spins in the furnace.
Also, our heater seems to come on A LOT. We have an electronic thermostat and I swear the heater goes on and off every 5 minutes.